Left ventricular discharge with Impella for 30 minutes before PCI is associated with reduced infarct size in STEMI patients

Results from a new per-protocol analysis of data from the ST-segment Elevation Myocardial Infarction Door-To-Unload (STEMI DTU) pilot study show significantly reduced infarct size in patients undergoing left ventricular (LV) unloading with Impella CP . For 30 minutes before percutaneous coronary intervention (PCI) compared to patients undergoing LV unloading immediately followed by PCI. The data were presented today at the 2022 Transcatheter Cardiovascular Therapeutics (TCT) conference in Boston by Dr. Navin K. Kapur, executive director of the Cardiovascular Center for Research and Innovation (CVCRI) at Tufts Medical Center and principal investigator of the pivotal randomized trial and checked STEMI DTU.

What is the logic of the STEMI DTU pilot trial? (from the editorial staff)

Despite a significant decrease in mortality due to acute myocardial infarction (AMI) since 1960, there has been a parallel increase in the incidence of heart failure. Pooled patient-level analysis from 10 randomized trials showed that the size of the infarct was strongly associated with mortality, and hospitalization for heart failure during the 1-year follow-up (Figure 1). Therefore, there is an important clinical need for interventions that can reduce myocardial damage during myocardial infarction.

Braunwald et al. in 1971 he suggested "that measures designed to reduce myocardial oxygen demand and improve coronary perfusion, if implemented promptly, could reduce the final size of a (myocardial) infarction." Since 1978, numerous preclinical studies have investigated whether reducing myocardial oxygen consumption by implementing a circulatory pump limits myocardial damage in IMA. Studies that have tested mechanical discharge using mechanical devices have shown that discharge before, not after reperfusion, is necessary to reduce the size of the heart attack.

Recently

preclinical studies have provided insights into the mechanisms by which the discharge of the left ventricle by the Impella® cardiac pump limits myocardial damage.

In 2015, using a pig model from AMI, Kapur et al. demonstrated that first venting the left ventricle using Impella CP® and then delaying reperfusion for 60 minutes. They were found to result in a reduction in left ventricular mean parietal stress and peak parietal stress relative to immediate reperfusion. Indeed, the extent of the wall stress reduction was directly related to the extent of the infarct reduction in size. Furthermore, the study demonstrated that left ventricular discharge with delayed reperfusion activated a cardioprotective signaling system that reduced cell death and resulted in a 43% reduction in myocardial infarction size.

Sole et al. explored the effects of the surgically implanted Impella LD® heart pump on left ventricular remodeling and function 1 month post-infarction in a porcine model. Left ventricular unloading, with Impella LD, was initiated 30 minutes before reperfusion and support was maintained for up to 120 minutes after reperfusion. Left ventricular unloading resulted in lower left ventricular pressure and wall stress and higher mean arterial pressure and cardiac output. Importantly, at the 1 month follow-up, the size of the infarct in pigs discharged LV was reduced by 50%. Based on these results, the authors concluded that early care with Impella LD in IMA limited remodeling of the left ventricle, thereby improving prognosis.

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