Cardiovascular Outcomes Using Intra-Aortic Balloon Pump in High-Risk Acute Myocardial Infarction With or Without Cardiogenic Shock: A Meta-Analysis

Background: Intra-aortic balloon pump (IABP) has been widely used ever since it was first developed in 1962 and became part of clinical practice in 1968. It is used to treat patients with complications of acute myocardial infarction (AMI) such as cardiogenic shock, refractory left ventricular failure, and for high-risk patients undergoing angioplasty and coronary artery bypass grafting. However, current literature demonstrates a significant variance in terms of indications for using IABP and its outcomes. The aim of this study is to review the existing literature to analyze whether the use of IABP offers any cardiovascular benefit to the patients with AMI and the complications associated with the use of IABP. Material and Methods: A systematic review of literature identified 16 studies. We analyzed the primary endpoint (in-hospital mortality, reinfarction, recurrent ischemia) and secondary endpoint (incidence of moderate and severe bleeding during hospitalization at 7 days). We estimated the proportion of between-study inconsistency (heterogeneity) due to true differences between studies (rather than differences due to random error or chance) using the I2 statistic. Mantel-Haenszel fixed-effect model was used to calculate the combined relative risks (RRs) when studies were homogenous, and the random effect model was used when studies were heterogenic. A 2-sided alpha error < .05 was considered statistically significant. Results: Meta-analysis revealed that in-hospital mortality of patients with AMI with and without cardiogenic shock did not differ between IABP group as compared to no IABP group (RR: 1.11; confidence interval [CI]: 0.69-1.78; P = .67). However, analysis of patients with AMI with cardiogenic shock showed statistically significant improvement in mortality (RR: 0.72; CI: 0.60-0.86; P < .0004). There was no significant reduction in the rate of reinfarction (RR: 0.81; CI: 0.30-2.17; P = .67) or recurrent ischemia (RR: 0.78; CI: 0.34-1.78; P = .55) using IABP. Intra-aortic balloon pump was found to significantly increase the risk of moderate bleeding (RR: 1.71; CI: 1.03-2.85; P = .04) and major bleeding (RR: 4.01; CI: 2.66-6.06; P < .0001). Conclusion: The present meta-analysis suggests that patients with high-risk AMI without cardiogenic shock do not seem to benefit from the use of IABP as measured by in-hospital mortality, rate of reinfarction, and recurrent angina. However, in patients with AMI with cardiogenic shock (systolic blood pressure [SBP] < 90), there was significant reduction in mortality using IABP. The use of IABP is associated with increase in the rate of both moderate and severe bleeding.