The BVS experience
With data from studies that directly compared BVS and metallic stents still a few years off, the only indications of BVS performance now available come from either single- or multicenter registries. The thrust of much of these data presented at EuroPCR was that BVS have performed well as interventionalists have moved in the months since BVS became available for routine use to placing them in sicker patients and in patients with more complex coronary lesions.
Mitchel L. Zoler/Frontline Medical News
Dr. Julinda Mehilli
The largest registry is ABSORB First, a voluntary-reporting registry that began in January 2013 and involves about 90 centers in countries where Absorb is commercially available in Europe, Asia, New Zealand, and Columbia. Dr. Eric Eeckhout, a cardiologist at Batiment Hospital in Lausanne, Switzerland, reported procedural and 30-day outcome data for the first 800 of the 1,305 patients enrolled in the registry as of May 2014.
Unlike previously reported multicenter series of patients getting BVS, these patients included 46% with at least two affected coronary arteries, 29% with stable angina, 15% with unstable angina, and 35% with an acute or recent MI. Significant calcification was present in 20% of the treated coronaries, 12% of the treated coronary stenoses were located at bifurcations, 12% of the coronaries featured extensive tortuosity, 11% had total occlusions, and 6% had ostial lesions. Lesion complexity scoring based on the American Heart Association and American College of Cardiology method rated 24% of the stenoses type C lesions and another 23% rated as B2 lesions. In addition, 38% of the lesions were at least 20 mm long.
Despite the challenging anatomy that many patients featured, device success occurred in 99% of the patients and procedure success in 98%, reported Dr. Eeckhout. Bailout treatment with a metal stent was needed in five patients (0.6%). During the 30 days following treatment the 800 patients had no deaths, and two cases (0.3%) of definite or probably stent thrombosis with both episodes occurring 1-30 days after scaffold placement – low rates given the complexity of the patients and lesions treated.
"These findings suggest the early safety and performance of Absorb in complex, real-world patients in daily PCI use," Dr. Eeckhout said. "Probably the operators [who treated these 800 patients] knew how to handle a BVS and they were able to expand to more complex pathology without an impact on safety or efficacy," he noted, adding that the "excellent results reflect the increasing experience of interventional cardiologists who use BVS; complexity did not impact efficacy or safety."
"These were "extraordinarily good outcomes in very complex patients," commented Dr. Stone, but he cautioned that the follow-up so far has been brief and that this was a "self-reported" registry, so it is possible that some operators failed to report some of their complications.
Other registry data reported at EuroPCR had longer follow-up, in some cases out to as long as 1 year, but in smaller patient sets and at fewer centers. These series represent "real world" use of BVS at these centers since Absorb came onto the European market in September 2012. Soon after BVS became commercially available, the interventionalists at these centers decided to use them in whichever patients they could regardless of their clinical status – in patients with acute coronary syndrome as well as stable patients, and regardless of lesion type or location. This contrasted with the initial, preapproval trials of BVS that excluded unstable patients and patients with complex coronary lesions or lesions in challenging sites, such as bifurcations or at an arterial ostium.
Findings from several ongoing registries were reported at EuroPCR:
• A group of six German centers had 1-year follow-up on 181 patients. Two thirds had class B2 or C lesions, 16% of lesions were calcified, and 14% involved side branches. These patients had a 5% rate of major adverse coronary events in the first year with no episodes of stent thrombosis, a result comparable with the pivotal trials for second-generation drug-eluting metallic stents as well as the early BVS studies that enrolled patients with simpler lesions, noted Dr. Thomas Schmitz, a cardiologist at the Contilla Heart and Vascular Center in Essen, Germany.
• Single-center experience at the Thoraxcenter in Rotterdam included 6-month follow-up on the first 180 of what are now more than 600 patients who have received BVS at the Thoraxcenter since it came onto the market. The series featured 48% of patients with calcified lesions, 41% with type B2 or C lesions, 38% of patients with multivessel disease, and lesion lengths up to 25 mm. Many patients received a BVS acutely after a ST-segment MI. Device success occurred in 98% of patients. The 6-month rate of major adverse coronary events was 3.3%, with definite or probable stent thrombosis in 2%, and 2% required target-lesion revascularization during 6 months of follow-up. "We had very good results in a complex group of patients that is getting closer to the real world by including patients with unstable and stable angina and ST-elevation myocardial infarction," said Dr. Robert-Jan van Geuns, a cardiologist at the Thoraxcenter. "We got stentlike results using a temporary scaffold. But we want to improve the flexibility of the BVS, reduce strut thickness, and make the procedures easier," he said.
• Interventionalists at Ferrarotto University Hospital in Catania, Italy, decided in March 2013 to start placing BVS when they could "regardless of lesion location or complexity." By this past May they had treated 367 lesions in 289 patients with BVS and had 6-month follow-up on 169 patients and 12-month follow-up on 48, said Dr. Corrado Tamburino, professor of cardiology and director of clinical cardiology at Ferrarotto. Half of their BVS patients had acute coronary syndrome, including 18% with ST-elevation MI, 17% with unstable angina, and 15% with non-STEMI. Half the treated lesions were class C or B2, 27% of patients had two or more lesions, 16% were at bifurcations, 9% were chronic total occlusions, and the mean lesion length was 21 mm. The operators successfully delivered BVS into 98% of patients. Among patients with 6-months’ follow-up, the incidence of major adverse coronary events was 2%, with no episodes of stent thrombosis after 30 days. The series included two deaths: one in a patient who stopped dual-antiplatelet therapy (DAPT) after 25 days and another in a patient who had an arterial dissection. All the BVS thromboses occurred within the first 30 days, "meaning it’s a technical issue. You need to always do lesion preparation, proper sizing [of the BVS for the artery it is entering], and post dilatation. If you do all that, you reduce the risk of thrombosis," he explained. The findings showed that placing "BVS is feasible and safe in the real world, and is effective at midterm follow-up. Stent thrombosis is not an issue if the procedural steps are respected. We expect similar results after 1 and 2 years, but we need to wait and be cautious," Dr. Tamburino said.