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Cardiogenic shock, which develops as a serious complication in around 8-10% of ST-elevation myocardial infarction (STEMI) patients, is associated with a mortality rate of 40-50%. It is beneficial to ensure perfusion using mechanical circulatory support in cardiogenic shock. Extracorporeal life support ensures both blood flow and oxygenation of the blood. However, extracorporeal life support has been associated with complications of excessive bleeding and limb ischemia. Percutaneous microaxial flow pumps are a type of active mechanical circulatory support. These pumps drain blood from the left ventricle through a catheter and throw it into the ascending aorta. More information is needed on the results of routine use of the microaxial flow pump in patients with STEMI-associated cardiogenic shock.

This study investigated the benefit of the microaxial heart pump in cardiogenic shock due to STEMI.

Patients with cardiogenic shock due to STEMI were included in this international, multicenter, randomized study. The study group was randomized into 2 groups: microaxial flow pump (Impella CP) plus standard care and standard care only. The primary endpoint was death from any cause at 180 days, while the composite safety endpoint was severe bleeding, limb ischemia, hemolysis, device failure, or worsening aortic regurgitation.

One hundred seventy-nine patients were included in the Impella microaxial pump group and 176 in the standard treatment group. The median age of the patients was 67, and 79.2% were male. The primary outcome occurred in 45.8% (n=82) patients in the microaxial flow pump group and 58.5% (n=103) patients in the standard treatment group (HR=0.74, 95% CI 0.55-0.99, p=0.04). A composite safety endpoint event occurred in 24 % of patients (n=43) in the microaxial flow-pump group and 6.2% (n=11) in the standard care group (relative risk, 4.74; 95% CI, 2.36 to 9.55).

The use of a microaxial flow pump in combination with standard care in the treatment of patients with STEMI-associated cardiogenic shock reduced the risk of death from any cause at 180 days compared to standard care alone. However, this therapy increased the incidence of adverse events.

Interestingly, the benefit of Impella continues after 30 days. Survival curves continue to separate after the first 30 days. However, patients treated with Impella experience significantly more severe complications. More studies are needed to evaluate benefits in more diverse patient populations, examine how the duration of mechanical support may affect the rate of serious complications, and identify practices to minimize complications.