Intra-Aortic Balloon Pump for Acute MI | Journal Scan

Study Questions:

What is the efficacy of intra-aortic balloon pump (IABP) in acute myocardial infarction (AMI)?

Methods:

The investigators used data from human studies found in PubMed, Embase, and Cochrane libraries through December 2014, and in reference lists of selected articles. Search strings were “myocardial infarction” or “acute coronary syndrome” and “intra-aortic balloon pump” or “counterpulsation.” Randomized clinical trials (RCTs) and observational studies comparing use of IABP with no IABP in patients with AMI were selected. Two reviewers independently extracted the data, and risk of bias in RCTs was assessed using the Cochrane risk of bias tool. The authors conducted separate meta-analyses of the RCTs and observational studies. Data were quantitatively synthesized using random-effects meta-analysis. The primary outcome measure was 30-day mortality.

Results:

There were 12 eligible RCTs randomizing 2,123 patients. In the RCTs, IABP use had no statistically significant effect on mortality (odds ratio [OR], 0.96; 95% confidence interval [CI], 0.74-1.24), with no significant heterogeneity among trials (I2 = 0%; p = 0.52). This result was consistent when studies were stratified by the presence (OR, 0.94; 95% CI, 0.69-1.28; p = 0.69; I2 = 0%) or absence (OR, 0.98; 95% CI, 0.57-1.69; p = 0.95, I2 = 17%) of cardiogenic shock. There were 15 eligible observational studies totaling 15,530 patients. Their results were mutually conflicting (heterogeneity I2 = 97%; p < 0.001), causing wide uncertainty in the summary estimate for the association with mortality (OR, 0.96; 95% CI, 0.54-1.70). A simple index of baseline risk marker imbalance in the observational studies appeared to explain much of the heterogeneity in the observational data (R2meta = 46.2%; p < 0.001).

Conclusions:

The authors concluded that use of IABP was not found to improve mortality among patients with AMI in the RCTs, regardless of whether patients had cardiogenic shock.

Perspective:

This study reports that IABP therapy does not improve mortality in AMI in the populations studied in RCTs, regardless of the presence or absence of cardiogenic shock. Current evidence does not support the routine use of IABP in AMI patients with or without shock. Whether other mechanical circulatory assist devices such as the Impella or the TandemHeart device may have a role in these patients needs additional prospective study.

Clinical Topics: Acute Coronary Syndromes, Cardiac Surgery, Heart Failure and Cardiomyopathies, Cardiac Surgery and Heart Failure, Acute Heart Failure, Mechanical Circulatory Support

Keywords: Myocardial Infarction, Acute Coronary Syndrome, Counterpulsation, Intra-Aortic Balloon Pumping, Outcome Assessment (Health Care), Shock, Shock, Cardiogenic, Mortality, Uncertainty


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