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PARIS – Bioresorbable coronary stents programmed to disappear look like they are here to stay.
Late last year, interventional cardiology began its slow but inexorable shift from metallic coronary stents to bioresorbable scaffolds that disappear from arteries within a couple of years, and in newer models, within several months.
The first bioresorbable coronary stent, called a bioresorbable vascular scaffold (BVS), came out for routine use in Europe last September under the brand name Absorb. While the U.S. pivotal trial for this BVS launched only in January, as early as last September interventionalists at a few European centers felt so convinced by the BVS concept that they designated it their "default" device for percutaneous coronary interventions (PCI). While early European results from more than 200 patients treated with default BVS were generally encouraging, although not without a problem, default BVS currently operates with enough exclusions and caveats to warrant a big asterisk.
A major lesson from "default" use of BVS is that they are clearly not for everyone right now. The largest default bioresorbable program reported so far includes 176 BVS placed by PCI in 174 patients during September 2012 through April 2013 at the Thoraxcenter in Rotterdam. Those 176 interventions were out of 1,018 procedures done in 958 patients during the same 8-month period. Despite having declared their default device, Thoraxcenter interventionalists decided that they needed something other than a BVS for more than 80% of their PCI patients, Dr. Robert-Jan van Geuns reported at the annual meeting of the European Association of Percutaneous Coronary Interventions.
The data so far are limited, "from small registries," not the sort of evidence that changes practice, admitted Dr. van Geuns, "but I think we are seeing where we are going" with BVS.
"With BVS, there is the hope for therapeutic benefit with possible vessel remodeling," said Dr. Stephan Windecker, professor and chief of cardiology at University Hospital in Bern, Switzerland. "I think it may have long-term benefits that we do not see" with conventional drug-eluting metallic stents. "There is strong evidence for a different way of vessel remodeling when the scaffold disappears," said Dr. Windecker, expressing the widely held but still clinically unproven view that treating patients with stents that disappear once they’ve done their job will be better for patients than are standard metal stents that stay in place forever.
Two Rotterdam BVS registries
Dr. van Geuns did not specify all the criteria his group applied for targeting BVS, aside from saying in an interview that they were younger patients with relatively few comorbidities and a life expectancy of at least 2 years so that they could potentially benefit from long-term advantages after a BVS disappears.
The Thoraxcenter’s 174 BVS-treated patients included 41 patients with a ST-elevation myocardial infarction who entered a separate review, two with prior coronary artery bypass surgery, and 131 who underwent PCI for other reasons who were the focus of Dr. van Geuns’ report. Procedural and clinical success occurred in 126 of the 131 patients (95%). The only complications during median follow-up of 137 days were two cases of stent thrombosis, one myocardial infarction in a nontarget vessel that occurred during the first 30 days after treatment, and one death. The operators generally found BVS to be deliverable, though with longer procedure times, more wires needed, and more predilatation of the PCI vessel, compared with what’s usual for placing metallic coronary stents.
The Polish ACS registry
Two other series reported at the meeting used BVS as the default device in patients with acute coronary syndrome (ACS). The POLAR ACS (Polish Absorb Registry for ACS) enrolled 88 ACS patients who received at least one BVS during November 2012-May 2013 when participating centers used BVS as their default devices for PCI. Treatment also included aspiration thrombectomy in 15 patients (17%), and predilatation of the infarct-related artery in 78 patients (89%).
The BVS intervention had 100% procedural success and produced robust, TIMI grade III flow in all of the treated patients, reported Dr. Dariusz Dudek, professor and head of interventional cardiology at Jagiellonian University in Krakow, Poland. The BVS was "easy to deliver," he said. But after predilatation and before BVS placement, one patient had no reflow and two had slow flow. Following completion of the procedure, one patient continued to have slow flow and four patients needed bail-out placement of another BVS. The only major adverse coronary event during hospitalization was need for PCI outside the target vessel.
"The data indicate at least similar safety and efficacy for BVS as for current drug-eluting stents," said Dr. Dudek, We can start replacing drug-eluting metal stents with BVS in many cases, especially for focal stenoses in younger patients."
But Dr. Chaim Lotan voiced concern about the incidence of low and slow blood flow during and after the ACS procedures. "Reduction of flow predicts mortality," he warned. "I think this is related to the aggressive vessel preparation," said Dr. Lotan, director of the heart institute at Hadassah Medical Center in Jerusalem.
Dr. Dudek acknowledged that the predilatation with a noncompliant balloon that BVS requires can trigger slow or no flow in the infarct vessel.
In response, Dr. Ron Waksman defended the BVS concept. "We see 4% restenosis after 3 years, and 6% after 4 years" with conventional drug-eluting metal stents. "These are unacceptable numbers. BVS is a new technology that guarantees that after 3 years there is no stent," said Dr. Waksman, associate director of cardiology at MedStar Washington Hospital Center.
The Czech STEMI registry
A third European registry of default BVS that began late last year focused on patients treated for ST-elevation MI at a participating center in the Czech Republic during December 2012-May 2013. Of the 87 patients who presented at participating centers with STEMI, 22 patients (25%) met prespecified criteria for undergoing BVS treatment, a BVS penetration level similar to the rate in the Thoraxcenter series. One eligibility criteria was life expectancy of at least 3 years. The 21-treated patients received 27 of 28 BVS successfully; one BVS could not be placed because of vessel tortuosity. Nineteen of the 21-BVS-treated patients achieved TIMI III grade coronary flow after PCI, with the other two patients reaching grade II flow, reported Dr. Petr Widimský, professor and head of the cardiocenter at Charles University in Prague. Common reasons why STEMI patients did not receive a BVS included no stent needed; a vessel too wide (more than 4.0 mm) to be treated by existing BVS sizes; or the presence of pulmonary edema or shock. During follow-up, one patient had a reinfarction caused by BVS thrombosis 3 days after stopping ticagrelor, but no patients had any episodes of clinical restenosis during follow-up of up to 5 months.
Based on the experience so far in three reported programs using BVS to treat patients with STEMI the key for successful use in these patients seems to be treating appropriately-sized coronary arteries because the possibility to post-dilate the BVS without breaking it is limited, said Dr. van Geuns.
Despite limited experience so far using BVS in routine practice, experts see the penetration the devices have made so far as a model for the future of interventional cardiology. During one panel discussion on BVS at the meeting, the widely shared consensus was that within a decade BVS numbers will surpass metallic stents for PCI and truly be the default device, with use in three-quarters or more of PCI patients.
A larger BVS registry
A larger record of BVS performance reported at the meeting came from a registry of 450 patients followed for 1 year after receiving one or two BVS at centers that participated in the ABSORB EXTEND trial. Average lesion length treated was just under 12 mm, and 93% of patients had a single lesion. During 12 months of follow-up, patients had one death, 13 myocardial infarctions, and eight instances of ischemia-driven target-vessel revascularization, for an overall major adverse event rate of 4.2%, reported Dr. Patrick W. Serruys, professor of interventional cardiology at the Thoraxcenter. Four cases of scaffold thrombosis (0.9%) occurred during 1 year follow-up.
Dr. Serruys showed how the BVS outcomes from the 450 patients in this registry compared with a historical series of patients who received the Xience V everolimus-eluting coronary stent in the SPIRIT II (Eurointervention 2007;3:315-20) and SPIRIT III (JAMA 2008:299:1903-13) trials. The 12-month major adverse cardiac events (MACE) rate of 4.2%, scaffold thrombosis rate of 0.9%, and the 2.9% MI rate seen with the Absorb BVS in the registry compared well with the 5.3% MACE rate, 0.7% definite stent thrombosis rate, and 2.3% MI rate seen with Xience V in the two older trials, Dr. Serruys noted. The BVS had no significant safety and efficacy differences, compared with historic results from a drug-eluting, metallic stent comparator, but with the added potential benefit of disappearing from the patient.
High expectations for BVS
"The noninferiority of BVS has been well established in patients with simple [coronary] disease, but in patients with diffuse disease, BVS may well be superior," said Dr. Ibrahim Al-Rashdan, director of the cardiac catheterization laboratory at in Kuwait Heart Center. "We can use BVS to avoid a metal jacket with diffuse disease. But lesion preparation and good vessel sizing is mandatory. And if the vessel is calcified you must use a rotablator; if you have any doubt, use a rotablator." Another limitation of BVS is that because they are made from polymers, they break when overexpanded, and the currently available models are bulkier than metallic stents and their bulkiness demands predilatation of the artery receiving a BVS. "There is consensus to use BVS for long lesions, and for patients with diabetes," said Dr. van Geuns.
But despite this support for BVS, their reception may be tepid so far at the grassroots’ level. "People are afraid of BVS because it’s a plastic stent," said Dr. Dudek. But while he conceded that BVS use requires precautions, "the technique is not so different from a regular DES [drug-eluting stent]," he said.
"The ideal lesions for BVS are soft, with no calcifications, and enough compliance of the vessel wall to accommodate the device so you don’t need to worry about full stent expansion. With BVS, there is hope to have therapeutic benefit with possible vessel remodeling." said Dr. Windecker. "There is strong evidence for a different way of vessel remodeling" with lesion regression. "This may also happen with metal stents, but with a metal stent, the remodeling won’t benefit the lumen because of the metallic wires. We have preliminary data from coronary imaging that the coronary seems to grow" around a BVS "in a way that does not compromise the lumen," Dr. Windecker said in an interview.
A focus for continued BVS development will be patients with diabetes because of the "clear limitation of drug-eluting stents" in these patients, he said. Future studies will also try to establish that BVS can prevent plaque rupture.
Dr. van Geuns said that he has been a consultant to and received honoraria from Stentys and Abbott Vascular. Dr. Windecker said that he has received grant support from Abbott, Biotronik, Boston Scientific, and several other companies. Dr. Dudek said that he has been a consultant to Biotronik, Abbott, Medtronic, and Boston Scientific. Dr. Lotan said that he has been a consultant to and stockholder in InspireMD and that he has received honoraria from Medtronic and other companies. Dr. Waksman said that he has been a consultant to Biotronik, Abbott Vascular, Boston Scientific, and Medtronic. Dr. Widimský said that he has been a consultant to Abbott Vascular, Boston Scientific, Medtronic, and several other companies. Dr. Serruys said that he had no disclosures. Dr. Al-Rashdan said that he had no disclosures.
On Twitter @mitchelzoler
PARIS – Bioresorbable coronary stents programmed to disappear look like they are here to stay.
Late last year, interventional cardiology began its slow but inexorable shift from metallic coronary stents to bioresorbable scaffolds that disappear from arteries within a couple of years, and in newer models, within several months.
The first bioresorbable coronary stent, called a bioresorbable vascular scaffold (BVS), came out for routine use in Europe last September under the brand name Absorb. While the U.S. pivotal trial for this BVS launched only in January, as early as last September interventionalists at a few European centers felt so convinced by the BVS concept that they designated it their "default" device for percutaneous coronary interventions (PCI). While early European results from more than 200 patients treated with default BVS were generally encouraging, although not without a problem, default BVS currently operates with enough exclusions and caveats to warrant a big asterisk.
A major lesson from "default" use of BVS is that they are clearly not for everyone right now. The largest default bioresorbable program reported so far includes 176 BVS placed by PCI in 174 patients during September 2012 through April 2013 at the Thoraxcenter in Rotterdam. Those 176 interventions were out of 1,018 procedures done in 958 patients during the same 8-month period. Despite having declared their default device, Thoraxcenter interventionalists decided that they needed something other than a BVS for more than 80% of their PCI patients, Dr. Robert-Jan van Geuns reported at the annual meeting of the European Association of Percutaneous Coronary Interventions.
The data so far are limited, "from small registries," not the sort of evidence that changes practice, admitted Dr. van Geuns, "but I think we are seeing where we are going" with BVS.
"With BVS, there is the hope for therapeutic benefit with possible vessel remodeling," said Dr. Stephan Windecker, professor and chief of cardiology at University Hospital in Bern, Switzerland. "I think it may have long-term benefits that we do not see" with conventional drug-eluting metallic stents. "There is strong evidence for a different way of vessel remodeling when the scaffold disappears," said Dr. Windecker, expressing the widely held but still clinically unproven view that treating patients with stents that disappear once they’ve done their job will be better for patients than are standard metal stents that stay in place forever.
Two Rotterdam BVS registries
Dr. van Geuns did not specify all the criteria his group applied for targeting BVS, aside from saying in an interview that they were younger patients with relatively few comorbidities and a life expectancy of at least 2 years so that they could potentially benefit from long-term advantages after a BVS disappears.
The Thoraxcenter’s 174 BVS-treated patients included 41 patients with a ST-elevation myocardial infarction who entered a separate review, two with prior coronary artery bypass surgery, and 131 who underwent PCI for other reasons who were the focus of Dr. van Geuns’ report. Procedural and clinical success occurred in 126 of the 131 patients (95%). The only complications during median follow-up of 137 days were two cases of stent thrombosis, one myocardial infarction in a nontarget vessel that occurred during the first 30 days after treatment, and one death. The operators generally found BVS to be deliverable, though with longer procedure times, more wires needed, and more predilatation of the PCI vessel, compared with what’s usual for placing metallic coronary stents.
The Polish ACS registry
Two other series reported at the meeting used BVS as the default device in patients with acute coronary syndrome (ACS). The POLAR ACS (Polish Absorb Registry for ACS) enrolled 88 ACS patients who received at least one BVS during November 2012-May 2013 when participating centers used BVS as their default devices for PCI. Treatment also included aspiration thrombectomy in 15 patients (17%), and predilatation of the infarct-related artery in 78 patients (89%).
The BVS intervention had 100% procedural success and produced robust, TIMI grade III flow in all of the treated patients, reported Dr. Dariusz Dudek, professor and head of interventional cardiology at Jagiellonian University in Krakow, Poland. The BVS was "easy to deliver," he said. But after predilatation and before BVS placement, one patient had no reflow and two had slow flow. Following completion of the procedure, one patient continued to have slow flow and four patients needed bail-out placement of another BVS. The only major adverse coronary event during hospitalization was need for PCI outside the target vessel.
"The data indicate at least similar safety and efficacy for BVS as for current drug-eluting stents," said Dr. Dudek, We can start replacing drug-eluting metal stents with BVS in many cases, especially for focal stenoses in younger patients."
But Dr. Chaim Lotan voiced concern about the incidence of low and slow blood flow during and after the ACS procedures. "Reduction of flow predicts mortality," he warned. "I think this is related to the aggressive vessel preparation," said Dr. Lotan, director of the heart institute at Hadassah Medical Center in Jerusalem.
Dr. Dudek acknowledged that the predilatation with a noncompliant balloon that BVS requires can trigger slow or no flow in the infarct vessel.
In response, Dr. Ron Waksman defended the BVS concept. "We see 4% restenosis after 3 years, and 6% after 4 years" with conventional drug-eluting metal stents. "These are unacceptable numbers. BVS is a new technology that guarantees that after 3 years there is no stent," said Dr. Waksman, associate director of cardiology at MedStar Washington Hospital Center.
The Czech STEMI registry
A third European registry of default BVS that began late last year focused on patients treated for ST-elevation MI at a participating center in the Czech Republic during December 2012-May 2013. Of the 87 patients who presented at participating centers with STEMI, 22 patients (25%) met prespecified criteria for undergoing BVS treatment, a BVS penetration level similar to the rate in the Thoraxcenter series. One eligibility criteria was life expectancy of at least 3 years. The 21-treated patients received 27 of 28 BVS successfully; one BVS could not be placed because of vessel tortuosity. Nineteen of the 21-BVS-treated patients achieved TIMI III grade coronary flow after PCI, with the other two patients reaching grade II flow, reported Dr. Petr Widimský, professor and head of the cardiocenter at Charles University in Prague. Common reasons why STEMI patients did not receive a BVS included no stent needed; a vessel too wide (more than 4.0 mm) to be treated by existing BVS sizes; or the presence of pulmonary edema or shock. During follow-up, one patient had a reinfarction caused by BVS thrombosis 3 days after stopping ticagrelor, but no patients had any episodes of clinical restenosis during follow-up of up to 5 months.
Based on the experience so far in three reported programs using BVS to treat patients with STEMI the key for successful use in these patients seems to be treating appropriately-sized coronary arteries because the possibility to post-dilate the BVS without breaking it is limited, said Dr. van Geuns.
Despite limited experience so far using BVS in routine practice, experts see the penetration the devices have made so far as a model for the future of interventional cardiology. During one panel discussion on BVS at the meeting, the widely shared consensus was that within a decade BVS numbers will surpass metallic stents for PCI and truly be the default device, with use in three-quarters or more of PCI patients.
A larger BVS registry
A larger record of BVS performance reported at the meeting came from a registry of 450 patients followed for 1 year after receiving one or two BVS at centers that participated in the ABSORB EXTEND trial. Average lesion length treated was just under 12 mm, and 93% of patients had a single lesion. During 12 months of follow-up, patients had one death, 13 myocardial infarctions, and eight instances of ischemia-driven target-vessel revascularization, for an overall major adverse event rate of 4.2%, reported Dr. Patrick W. Serruys, professor of interventional cardiology at the Thoraxcenter. Four cases of scaffold thrombosis (0.9%) occurred during 1 year follow-up.
Dr. Serruys showed how the BVS outcomes from the 450 patients in this registry compared with a historical series of patients who received the Xience V everolimus-eluting coronary stent in the SPIRIT II (Eurointervention 2007;3:315-20) and SPIRIT III (JAMA 2008:299:1903-13) trials. The 12-month major adverse cardiac events (MACE) rate of 4.2%, scaffold thrombosis rate of 0.9%, and the 2.9% MI rate seen with the Absorb BVS in the registry compared well with the 5.3% MACE rate, 0.7% definite stent thrombosis rate, and 2.3% MI rate seen with Xience V in the two older trials, Dr. Serruys noted. The BVS had no significant safety and efficacy differences, compared with historic results from a drug-eluting, metallic stent comparator, but with the added potential benefit of disappearing from the patient.
High expectations for BVS
"The noninferiority of BVS has been well established in patients with simple [coronary] disease, but in patients with diffuse disease, BVS may well be superior," said Dr. Ibrahim Al-Rashdan, director of the cardiac catheterization laboratory at in Kuwait Heart Center. "We can use BVS to avoid a metal jacket with diffuse disease. But lesion preparation and good vessel sizing is mandatory. And if the vessel is calcified you must use a rotablator; if you have any doubt, use a rotablator." Another limitation of BVS is that because they are made from polymers, they break when overexpanded, and the currently available models are bulkier than metallic stents and their bulkiness demands predilatation of the artery receiving a BVS. "There is consensus to use BVS for long lesions, and for patients with diabetes," said Dr. van Geuns.
But despite this support for BVS, their reception may be tepid so far at the grassroots’ level. "People are afraid of BVS because it’s a plastic stent," said Dr. Dudek. But while he conceded that BVS use requires precautions, "the technique is not so different from a regular DES [drug-eluting stent]," he said.
"The ideal lesions for BVS are soft, with no calcifications, and enough compliance of the vessel wall to accommodate the device so you don’t need to worry about full stent expansion. With BVS, there is hope to have therapeutic benefit with possible vessel remodeling." said Dr. Windecker. "There is strong evidence for a different way of vessel remodeling" with lesion regression. "This may also happen with metal stents, but with a metal stent, the remodeling won’t benefit the lumen because of the metallic wires. We have preliminary data from coronary imaging that the coronary seems to grow" around a BVS "in a way that does not compromise the lumen," Dr. Windecker said in an interview.
A focus for continued BVS development will be patients with diabetes because of the "clear limitation of drug-eluting stents" in these patients, he said. Future studies will also try to establish that BVS can prevent plaque rupture.
Dr. van Geuns said that he has been a consultant to and received honoraria from Stentys and Abbott Vascular. Dr. Windecker said that he has received grant support from Abbott, Biotronik, Boston Scientific, and several other companies. Dr. Dudek said that he has been a consultant to Biotronik, Abbott, Medtronic, and Boston Scientific. Dr. Lotan said that he has been a consultant to and stockholder in InspireMD and that he has received honoraria from Medtronic and other companies. Dr. Waksman said that he has been a consultant to Biotronik, Abbott Vascular, Boston Scientific, and Medtronic. Dr. Widimský said that he has been a consultant to Abbott Vascular, Boston Scientific, Medtronic, and several other companies. Dr. Serruys said that he had no disclosures. Dr. Al-Rashdan said that he had no disclosures.
On Twitter @mitchelzoler
PARIS – Bioresorbable coronary stents programmed to disappear look like they are here to stay.
Late last year, interventional cardiology began its slow but inexorable shift from metallic coronary stents to bioresorbable scaffolds that disappear from arteries within a couple of years, and in newer models, within several months.
The first bioresorbable coronary stent, called a bioresorbable vascular scaffold (BVS), came out for routine use in Europe last September under the brand name Absorb. While the U.S. pivotal trial for this BVS launched only in January, as early as last September interventionalists at a few European centers felt so convinced by the BVS concept that they designated it their "default" device for percutaneous coronary interventions (PCI). While early European results from more than 200 patients treated with default BVS were generally encouraging, although not without a problem, default BVS currently operates with enough exclusions and caveats to warrant a big asterisk.
A major lesson from "default" use of BVS is that they are clearly not for everyone right now. The largest default bioresorbable program reported so far includes 176 BVS placed by PCI in 174 patients during September 2012 through April 2013 at the Thoraxcenter in Rotterdam. Those 176 interventions were out of 1,018 procedures done in 958 patients during the same 8-month period. Despite having declared their default device, Thoraxcenter interventionalists decided that they needed something other than a BVS for more than 80% of their PCI patients, Dr. Robert-Jan van Geuns reported at the annual meeting of the European Association of Percutaneous Coronary Interventions.
The data so far are limited, "from small registries," not the sort of evidence that changes practice, admitted Dr. van Geuns, "but I think we are seeing where we are going" with BVS.
"With BVS, there is the hope for therapeutic benefit with possible vessel remodeling," said Dr. Stephan Windecker, professor and chief of cardiology at University Hospital in Bern, Switzerland. "I think it may have long-term benefits that we do not see" with conventional drug-eluting metallic stents. "There is strong evidence for a different way of vessel remodeling when the scaffold disappears," said Dr. Windecker, expressing the widely held but still clinically unproven view that treating patients with stents that disappear once they’ve done their job will be better for patients than are standard metal stents that stay in place forever.
Two Rotterdam BVS registries
Dr. van Geuns did not specify all the criteria his group applied for targeting BVS, aside from saying in an interview that they were younger patients with relatively few comorbidities and a life expectancy of at least 2 years so that they could potentially benefit from long-term advantages after a BVS disappears.
The Thoraxcenter’s 174 BVS-treated patients included 41 patients with a ST-elevation myocardial infarction who entered a separate review, two with prior coronary artery bypass surgery, and 131 who underwent PCI for other reasons who were the focus of Dr. van Geuns’ report. Procedural and clinical success occurred in 126 of the 131 patients (95%). The only complications during median follow-up of 137 days were two cases of stent thrombosis, one myocardial infarction in a nontarget vessel that occurred during the first 30 days after treatment, and one death. The operators generally found BVS to be deliverable, though with longer procedure times, more wires needed, and more predilatation of the PCI vessel, compared with what’s usual for placing metallic coronary stents.
The Polish ACS registry
Two other series reported at the meeting used BVS as the default device in patients with acute coronary syndrome (ACS). The POLAR ACS (Polish Absorb Registry for ACS) enrolled 88 ACS patients who received at least one BVS during November 2012-May 2013 when participating centers used BVS as their default devices for PCI. Treatment also included aspiration thrombectomy in 15 patients (17%), and predilatation of the infarct-related artery in 78 patients (89%).
The BVS intervention had 100% procedural success and produced robust, TIMI grade III flow in all of the treated patients, reported Dr. Dariusz Dudek, professor and head of interventional cardiology at Jagiellonian University in Krakow, Poland. The BVS was "easy to deliver," he said. But after predilatation and before BVS placement, one patient had no reflow and two had slow flow. Following completion of the procedure, one patient continued to have slow flow and four patients needed bail-out placement of another BVS. The only major adverse coronary event during hospitalization was need for PCI outside the target vessel.
"The data indicate at least similar safety and efficacy for BVS as for current drug-eluting stents," said Dr. Dudek, We can start replacing drug-eluting metal stents with BVS in many cases, especially for focal stenoses in younger patients."
But Dr. Chaim Lotan voiced concern about the incidence of low and slow blood flow during and after the ACS procedures. "Reduction of flow predicts mortality," he warned. "I think this is related to the aggressive vessel preparation," said Dr. Lotan, director of the heart institute at Hadassah Medical Center in Jerusalem.
Dr. Dudek acknowledged that the predilatation with a noncompliant balloon that BVS requires can trigger slow or no flow in the infarct vessel.
In response, Dr. Ron Waksman defended the BVS concept. "We see 4% restenosis after 3 years, and 6% after 4 years" with conventional drug-eluting metal stents. "These are unacceptable numbers. BVS is a new technology that guarantees that after 3 years there is no stent," said Dr. Waksman, associate director of cardiology at MedStar Washington Hospital Center.
The Czech STEMI registry
A third European registry of default BVS that began late last year focused on patients treated for ST-elevation MI at a participating center in the Czech Republic during December 2012-May 2013. Of the 87 patients who presented at participating centers with STEMI, 22 patients (25%) met prespecified criteria for undergoing BVS treatment, a BVS penetration level similar to the rate in the Thoraxcenter series. One eligibility criteria was life expectancy of at least 3 years. The 21-treated patients received 27 of 28 BVS successfully; one BVS could not be placed because of vessel tortuosity. Nineteen of the 21-BVS-treated patients achieved TIMI III grade coronary flow after PCI, with the other two patients reaching grade II flow, reported Dr. Petr Widimský, professor and head of the cardiocenter at Charles University in Prague. Common reasons why STEMI patients did not receive a BVS included no stent needed; a vessel too wide (more than 4.0 mm) to be treated by existing BVS sizes; or the presence of pulmonary edema or shock. During follow-up, one patient had a reinfarction caused by BVS thrombosis 3 days after stopping ticagrelor, but no patients had any episodes of clinical restenosis during follow-up of up to 5 months.
Based on the experience so far in three reported programs using BVS to treat patients with STEMI the key for successful use in these patients seems to be treating appropriately-sized coronary arteries because the possibility to post-dilate the BVS without breaking it is limited, said Dr. van Geuns.
Despite limited experience so far using BVS in routine practice, experts see the penetration the devices have made so far as a model for the future of interventional cardiology. During one panel discussion on BVS at the meeting, the widely shared consensus was that within a decade BVS numbers will surpass metallic stents for PCI and truly be the default device, with use in three-quarters or more of PCI patients.
A larger BVS registry
A larger record of BVS performance reported at the meeting came from a registry of 450 patients followed for 1 year after receiving one or two BVS at centers that participated in the ABSORB EXTEND trial. Average lesion length treated was just under 12 mm, and 93% of patients had a single lesion. During 12 months of follow-up, patients had one death, 13 myocardial infarctions, and eight instances of ischemia-driven target-vessel revascularization, for an overall major adverse event rate of 4.2%, reported Dr. Patrick W. Serruys, professor of interventional cardiology at the Thoraxcenter. Four cases of scaffold thrombosis (0.9%) occurred during 1 year follow-up.
Dr. Serruys showed how the BVS outcomes from the 450 patients in this registry compared with a historical series of patients who received the Xience V everolimus-eluting coronary stent in the SPIRIT II (Eurointervention 2007;3:315-20) and SPIRIT III (JAMA 2008:299:1903-13) trials. The 12-month major adverse cardiac events (MACE) rate of 4.2%, scaffold thrombosis rate of 0.9%, and the 2.9% MI rate seen with the Absorb BVS in the registry compared well with the 5.3% MACE rate, 0.7% definite stent thrombosis rate, and 2.3% MI rate seen with Xience V in the two older trials, Dr. Serruys noted. The BVS had no significant safety and efficacy differences, compared with historic results from a drug-eluting, metallic stent comparator, but with the added potential benefit of disappearing from the patient.
High expectations for BVS
"The noninferiority of BVS has been well established in patients with simple [coronary] disease, but in patients with diffuse disease, BVS may well be superior," said Dr. Ibrahim Al-Rashdan, director of the cardiac catheterization laboratory at in Kuwait Heart Center. "We can use BVS to avoid a metal jacket with diffuse disease. But lesion preparation and good vessel sizing is mandatory. And if the vessel is calcified you must use a rotablator; if you have any doubt, use a rotablator." Another limitation of BVS is that because they are made from polymers, they break when overexpanded, and the currently available models are bulkier than metallic stents and their bulkiness demands predilatation of the artery receiving a BVS. "There is consensus to use BVS for long lesions, and for patients with diabetes," said Dr. van Geuns.
But despite this support for BVS, their reception may be tepid so far at the grassroots’ level. "People are afraid of BVS because it’s a plastic stent," said Dr. Dudek. But while he conceded that BVS use requires precautions, "the technique is not so different from a regular DES [drug-eluting stent]," he said.
"The ideal lesions for BVS are soft, with no calcifications, and enough compliance of the vessel wall to accommodate the device so you don’t need to worry about full stent expansion. With BVS, there is hope to have therapeutic benefit with possible vessel remodeling." said Dr. Windecker. "There is strong evidence for a different way of vessel remodeling" with lesion regression. "This may also happen with metal stents, but with a metal stent, the remodeling won’t benefit the lumen because of the metallic wires. We have preliminary data from coronary imaging that the coronary seems to grow" around a BVS "in a way that does not compromise the lumen," Dr. Windecker said in an interview.
A focus for continued BVS development will be patients with diabetes because of the "clear limitation of drug-eluting stents" in these patients, he said. Future studies will also try to establish that BVS can prevent plaque rupture.
Dr. van Geuns said that he has been a consultant to and received honoraria from Stentys and Abbott Vascular. Dr. Windecker said that he has received grant support from Abbott, Biotronik, Boston Scientific, and several other companies. Dr. Dudek said that he has been a consultant to Biotronik, Abbott, Medtronic, and Boston Scientific. Dr. Lotan said that he has been a consultant to and stockholder in InspireMD and that he has received honoraria from Medtronic and other companies. Dr. Waksman said that he has been a consultant to Biotronik, Abbott Vascular, Boston Scientific, and Medtronic. Dr. Widimský said that he has been a consultant to Abbott Vascular, Boston Scientific, Medtronic, and several other companies. Dr. Serruys said that he had no disclosures. Dr. Al-Rashdan said that he had no disclosures.
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EXPERT OPINION FROM EUROPCR 2013
