Mechanical circulatory support for refractory cardiogenic shock post-acute myocardial infarction-a decade of lessons

Abstract

Background: There are 0.9 catheterization labs per 100,000 inhabitants in Scotland for percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI), which are much less accessible to patients in remote and rural areas. An uncommon but sinister sequalae following AMI is cardiogenic shock (CS) that could be refractory to inotropic support. CS complicates 5-15% of AMIs occurring in ST-segment elevation myocardial infarctions (STEMIs). Outcomes of CS are poor with mortalities of up to 90% reported in the literature in the absence of experienced care. We report our experience as the tertiary referral centre in Scotland for MCS and heart transplantation over 8 years.

Methods: A retrospective review of prospectively collected data was undertaken on all patients registered to the MCS service. The database was interrogated for patient demographics, type of mechanical circulatory support (MCS) and duration of MCS support, PCI-outcomes and survival to 30 days. A time-to-event analysis was performed using patient survival as the primary outcome measure.

Results: Twenty-three patients (16 male, 7 females) were included. The median age of the patients as 50 years (range, 45-56 years). VA-ECMO was the initial MCS of choice in 17 (73.9%) patients with BIVAD for 4 (17.4%) patients and LVAD for 2 (8.7%) patients. Thirty-day mortality was 21.8% in this cohort, however survival to discharge was 52.2%. Eleven (47.8%) patients recovered without the need for any further support, however only 9 (81.8%) patients in this subgroup survived to discharge. Three (13.0%) patients received a durable LVAD. In this subgroup, one patient was transplanted whereas two patients died due to complications while on support. The median length of in-hospital MCS support was 4 days. Median in-hospital stay was 27 days. Long-term follow up of up to 8 years demonstrates a high mortality beyond 30-day up to the first 6-month post MCS support.

Conclusions: MCS usage in these patients carries a high mortality in the early post-implantation period. However, there is a significant benefit to patients who survive the initial bridging period to recovery or destination therapy.

Keywords: Mechanical circulatory support (MCS); cardiogenic shock (CS); extracorporeal membranous oxygenation (ECMO); intra-aortic balloon pump (IABP); myocardial infarction; ventricular assist device (VAD).

Figure 1

Kaplan-Meier curve showing 30-day survival.

Figure 2

Kaplan-Meier curve showing outcomes at up to 8 years follow-up.