Left Ventricular Assist Devices for Acute Myocardial Infarct Size Reduction: Meta-analysis

Negative Impact of Acute Reloading after Mechanical Left Ventricular Unloading

Mechanical LV unloading for acute myocardial infarction (MI) is a promising supportive therapy to reperfusion. However, no data is available on exit strategy. We evaluated hemodynamic and cellular effects of reloading after Impella-mediated LV unloading in Yorkshire pigs. First, we conducted an acute study in normal heart to observe effects of unloading and reloading independent of MI-induced ischemic effects. We then completed an MI study to investigate optimal exit strategy on one-week infarct size, no-reflow area, and LV function with different reloading speeds. Initial studies showed that acute reloading causes an immediate rise in end-diastolic wall stress followed by a significant increase in cardiomyocyte apoptosis. The MI study did not result in any statistically significant findings; however, numerically smaller average infarct size and no-reflow area in the gradual reloading group prompt further examination of reloading approach as an important clinically relevant consideration.

Update on Mechanical Circulatory Support

Mechanical circulatory support (MCS) devices provide temporary or intermediate- to long-term support for acute cardiopulmonary support. In the last 20 to 30 years, tremendous growth in MCS device usage has been seen. These devices offer support for isolated respiratory failure, isolated cardiac failure, or both. Initiation of MCS devices requires the input from multidisciplinary teams using patient factors and institutional resources to guide decision making, along with a planned "exit strategy" for bridge to decision, bridge to transplant, bridge to recovery, or as destination therapy. Important considerations for MCS use include patient selection, cannulation/insertion strategies, and complications of each device.

Mechanical Unloading of the Left Ventricle before Coronary Reperfusion in Preclinical Models of Myocardial Infarction without Cardiogenic Shock: A Meta-Analysis

Aim: to compare a conventional primary reperfusion strategy with a primary unloading approach before reperfusion in preclinical studies. Methods: we performed a meta-analysis of preclinical studies. The primary endpoint was infarct size (IS). Secondary endpoints were left ventricle end-diastolic pressure (LVEDP), mean arterial pressure (MAP), heart rate (HR), cardiac output (CO). We calculated mean differences (MDs) and associated 95% confidence intervals (CIs). Sensitivity and subgroup analyses on the primary and secondary endpoints, as well as a meta-regression on the primary endpoint using the year of publication as a covariate, were also conducted. Results: 11 studies (n = 142) were selected and entered in the meta-analysis. Primary unloading reduced IS (MD −28.82, 95% CI −35.78 to −21.86, I2 96%, p < 0.01) and LVEDP (MD −3.88, 95% CI −5.33 to −2.44, I2 56%, p = 0.02) and increased MAP (MD 7.26, 95% CI 1.40 to 13.12, I2 43%, p < 0.01) and HR (MD 5.26, 95% CI 1.97 to 8.55, I2 1%, p < 0.01), while being neutral on CO (MD −0.11, 95% CI −0.95 to 0.72, I2 88%, p = 0.79). Sensitivity and subgroup analyses showed, overall, consistent results. The meta-regression on the primary endpoint demonstrated a significant influence of the year of publication on effect estimate. Conclusions: in animal models of myocardial infarction, a primary unloading significantly reduces IS and exerts beneficial hemodynamic effects compared to a primary reperfusion.

Favorable Effects of Impella on Takotsubo Syndrome Complicated with Cardiogenic Shock

Reportedly, approximately 9.9%-12.4% of patients with Takotsubo syndrome (TTS) are complicated with cardiogenic shock (CS) and its prognosis remains poor even with the support of conventional mechanical circulatory assist devices including intra-aortic balloon pumping and venoarterial extracorporeal membrane oxygenation. Impella, a novel percutaneous left ventricular assist device, provides strong circulatory support together with the unloading of the left ventricle, and it is theoretically a promising mechanical circulatory assist device for TTS. In this case study, we report four consecutive patients with TTS complicated with CS who were successfully resuscitated using the Impella support.

Left ventricular unloading before percutaneous coronary intervention is associated with improved survival in patients with acute myocardial infarction complicated by cardiogenic shock: A systematic review and meta-analysis

BACKGROUND

Left ventricular unloading with Impella may improve survival outcomes in patients with acute myocardial infarction complicated by cardiogenic shock (AMI-CS). However, the optimal timing to initiate left ventricular unloading has yet to be established. Therefore, we conducted a systematic review and meta-analysis to compare survival in patients with AMI-CS who were supported with Impella prior to PCI (pre-PCI) to those in whom support was initiated following PCI (post-PCI).

METHODS

All studies that evaluated the impact of pre-PCI versus post-PCI Impella placement in patients with AMI-CS were included. Primary endpoints included in-hospital, 30-day, and 6-month survival rates.

RESULTS

We identified five observational studies comparing outcomes in 432 patients with AMI-CS, of which 173 patients were treated with Impella pre-PCI and 259 patients post-PCI. Patients in the pre-PCI group had lower in-hospital mortality compared to patients in the post-PCI group (RR 0.62, 95% CI: 0.50-0.76, I² = 0%). The lower mortality rate in the pre-PCI group remained evident at 30 days (HR 0.60, 95% CI: 0.47-0.78, I² = 0%) and at 6 months (HR 0.66, 95% CI: 0.44-0.97, I² = 0%). There was no difference in the risk of adverse events including reinfarction, stroke, major bleeding, acute ischemic limb, access site bleeding, and hemolysis.

CONCLUSIONS

In this meta-analysis of studies evaluating survival among AMI-CS patients with left ventricular unloading initiated pre- versus post-PCI, Impella placement prior to PCI was associated with improved survival.