WASHINGTON – The in-hospital team responsible for rapid management of ST-elevation myocardial infarction (STEMI) may also be the right team to manage pulmonary embolism (PE), according to a pilot study associating this approach with rapid treatment times and low overall mortality rates.
The data from the pilot study suggest that arming the STEMI team with a protocol for managing PE “is an effective means to care for patients with massive and submassive pulmonary embolism,” said Michael R. Kendall, MD, of the University of Southern California, Los Angeles. He presented the findings at the 2017 Cardiovascular Research Technologies meeting.
There are obvious parallels between STEMI and PE. Like STEMI, PE requires rapid diagnosis, triage, and when appropriate, an endovascular procedure. This led the USC investigators to consider a formal pilot study to test the premise that the STEMI team is in a position to deliver urgent care and good outcomes to PE patients.
The objective of the pilot study was “to evaluate treatment times and clinical outcome for patients with massive and submassive PE using a dedicated PE protocol,” Dr. Kendall explained. Massive PE was defined as hemodynamic instability with systolic blood pressure below 90 mm Hg or requiring inotropic support. Submassive PE was defined as systolic BP greater than 90 mm Hg with right heart dysfunction, such as a dilated right ventricle and elevated troponin levels.
Over an 18-month period beginning in June 2014, 40 PE patients were treated. The average age was 55 years, 50% were obese, 32% had renal insufficiency, 30% had recent surgery or had recently been immobilized, 30% had a history of deep venous thrombosis, and 28% had an active malignancy. At 43%, the largest single source of cases was the emergency department (ED), while 38% were transferred in from other centers, and 19% were already hospitalized at the time of the PE.
All patients underwent computed tomographic pulmonary angiography (CTPA) as part of the diagnostic procedure prior to an invasive angiogram. Patients received one or more different treatments upon confirmation of the PE, including catheter-directed thrombolytics, rheolytic thrombectomy, mechanical fragmentation, mechanical aspiration, and surgical pulmonary embolectomy. Inferior vena cava filters were used as appropriate.
At presentation, 10% were in cardiac arrest, 22% required intubation, and 12% required extracorporeal membrane oxygenation. On the basis of the diagnostic studies, 57% had a massive PE, and the remainder had submassive disease.
The average time from door to CTPA among those presenting to the ED was roughly 5 hours. It took, on average, an additional 2 hours from CTPA to an invasive angiogram, and another 3 hours to treatment, producing a total average door to treatment time of 10 hours.
Most patients received rheolytic thrombectomy, often with another form of treatment, such as catheter-directed thrombolytics, but 15% were treated with anticoagulation alone. Although a few patients improved sufficiently to obviate the need for an invasive procedure, the remainder of the patients received anticoagulation alone because of contraindications for invasive strategies or treatment refusal.
The average length of a hospital stay was 15 days. Bleeding events occurred in 10% of patients and 18% required a blood transfusion. Survival to hospital discharge was 82%. Although there was no control group, this rate of survival was considered favorable in the context of the severity of the PE.
Overall, delivery of urgent care for PE by a STEMI team was found feasible. Even though treatment approaches were not standardized, the protocol for diagnosing and managing PE on an urgent basis produced encouraging times for delivery of care and outcomes, according to the data presented by Dr. Kendall. Because of the differences in the composition and function of the STEMI team, Dr. Kendall indicated that it is difficult to predict similar success at other centers, but the findings overall were considered positive.
The senior author of the study, David M. Shavelle, MD, also at USC, suggested that the program there might be a template. He believes that the STEMI team has the skills to deliver prompt PE care, and he believes that this approach would be appropriate at other centers. He also suggested that such formal programs may be useful in establishing better treatment protocols.
“For PE, there are no clear guidelines for treatment time intervals, such as time from door to endovascular treatment,” Dr. Shavelle observed. He said that the wide variation of devices currently being used for treatment complicates efforts to develop clear clinical protocols and measure outcomes and “would like to see more standardization of treatment and registries to address these areas.”
Dr. Kendall reported no financial relationships.