San Diego, California — The overall in-hospital mortality rate for patients with cardiogenic shock after a heart attack was lower among patients treated with an intra-aortic balloon pump (IABP) than those treated without mechanical circulatory support (MCS), including those unable to undergo timely PCI, according to research to be presented at the SCAI 2015 Scientific Sessions. The researchers found no significant benefit of IABP on in-hospital mortality among cardiogenic shock patients who underwent timely PCI.

Mechanical circulatory support devices, such as IABP and Impella devices, provide a treatment option to boost hemodynamic function in certain patients with heart attack who present with cardiogenic shock (cardiac function that is too poor to support sufficient blood pressure and perfusion). These devices are an alternative for patients whose condition is refractory to medical management.

Data on the effectiveness of MCS devices in this patient population has been mixed. The previously published IABP-SHOCK II trial reported that IABPs did not reduce the 30-day mortality rate among this patient population. The most recent practice guidelines for the treatment of ST-elevation myocardial infarction (STEMI) downgraded MCS from a Class I to a Class IIa treatment recommendation.

"The use of MCS in patients with cardiogenic shock after STEMI is controversial in the current era. There has been a decrease in the utilization of IABP in the recent years, with a rise in utilization of devices like Impella," said Shikhar Agarwal, M.D., MPH, a cardiology fellow at the Cleveland Clinic, in Cleveland, Ohio.

Dr. Agarwal and colleagues sought to detail outcomes by reviewing real-world nationwide experience. They utilized the data from the 2003-2012 US Nationwide Inpatient Sample, the largest database in the United States that includes hospital data from all types of hospitals, to document trends and outcomes after utilization of MCS among patients with cardiogenic shock after STEMI. The researchers analyzed all admissions with a principal diagnosis of STEMI and cardiogenic shock and used ICD procedure codes to determine whether a MCS device, such as an IABP or an Impella, was used.

During the study period, there were 414,367 STEMI admissions, 35,944 (8.7%) cases with cardiogenic shock. Of all the STEMI admissions, 39,043 (9.2 percent) received MCS. The use of IABP in cardiogenic shock increased from 2003 to 2009, followed by a steady decline in its utilization in recent years. There has been a parallel increase in the utilization of Impella and TandemHeart.

Among patients undergoing timely PCI, in-hospital mortality among cardiogenic shock patients treated with IABP was 29.1 percent compared to 23.9 percent among those treated without IABP. Although confounded by survival bias, IABP utilization was associated with significantly lower mortality among patients unable to undergo timely PCI (34.7% versus 51.6%).

"Although the findings of lack of benefit of IABP among patients undergoing timely PCI are in sync with the IABP-SHOCK II trial, our results have helped carve out a potential niche for the use of IABP for cardiogenic shock patients unable to undergo timely PCI," said Dr. Agarwal.

Dr. Agarwal reports no relevant conflicts of interest.

Dr. Agarwal will be available at the SCAI 2015 ePosters Bar to discuss the study "Trends and Outcomes following Utilization of Mechanical Circulatory Support Devices in Patients with ST Elevation Myocardial Infarction" on Friday, May 8, at 1:00 p.m. (Pacific Time).