Abstract and Introduction
Abstract
Background Conflicting data on intra-aortic balloon counterpulsation (IABC) as adjunctive therapy in high-risk acute myocardial infarction (AMI) without cardiogenic shock (CS) have been published. We performed a meta-analysis of randomized trials evaluating the benefits of IABC in patients with AMI without CS.
Methods We searched Medline, EMBASE, the Cochrane Central Register of Controlled Trials, and relevant Web sites for randomized trials comparing IABC versus no IABC in patients with AMI without CS. No language, publication date, or publication status restrictions were applied. Primary end point was all-cause death. Secondary end points were congestive heart failure (CHF), reinfarction, recurrent myocardial ischemia, cerebrovascular accidents (CVA), and bleeding (moderate to severe) according to per protocol definitions.
Results Six trials were included (1,054 patients, 49.1% IABC vs 50.9% no IABC). At follow-up, counterpulsation does not reduce all-cause death (4.4% vs 4.1%, odds ratio [OR] [95% CI] 1.11 [0.49–2.54], P = .80), CHF (17.1% vs 18%, OR 0.92 [0.43–1.96], P = .83), or reinfarction (5.3% vs 7.7%, OR 0.68 [0.23–1.76], P = .42). Intra-aortic balloon counterpulsation versus no IABC significantly reduces recurrent myocardial ischemia (3.6% vs 20.3%, OR 0.15 [0.08–0.28], P < .00001), but it increases the risk of CVA (2% vs 0.3%, OR 4.39 [1.11–17.36], P = .03) and bleeding (21.4% vs 16.1%, respectively, OR 1.46 [1.05–2.04], P = .02).
Conclusions Counterpulsation does not reduce death, CHF, or reinfarction in patients with AMI without CS. The significant reduction of recurrent myocardial ischemia associated with IABC use is offset by a higher risk of CVAs and bleeding.
Introduction
The intra-aortic balloon counterpulsation (IABC) is an established tool that, through diastolic and systemic blood flow improvement, reduces afterload and myocardial work. According to this peculiarity, confirmed in previous animal studies, IABC has been extensively used in acute myocardial infarction (AMI) setting, particularly if complicated by cardiogenic shock (CS), aiming to improve hemodynamics.
Current guidelines recommend IABC only for patients with ST-elevation AMI presenting or developing hemodynamic instability (ie, CS or mechanical complications—class of recommendation I, level of evidence C or B). It is consistently advised to weigh the benefits of IABC against the complications that are related to bleeding or to device (mechanical, vascular, thromboemboli, or infections). Even in the absence of clear indications, IABC has been also used as a circulatory support during percutaneous coronary interventions (PCIs) in elective patients at high risk for hemodynamic instability, such as those with complex coronary lesions (ie, last remaining vessel or unprotected left main coronary artery disease) as well as in high-risk patients with AMI without CS.
Previous published trials were not powered to address the benefits of IABC versus no IABC in patients with AMI without CS and came to conflicting results. Indeed, the Randomized IABP Study Group trial concluded in favor of counterpulsation, whereas the PAMI II trial found IABC harmful. The recent Counterpulsation to Reduce Infarct Size Pre-PCI Acute Myocardial Infarction (CRISP AMI) trial suggested a clinical benefit of counterpulsation at 6-month follow-up despite that it did not reduce infarct size or 30-day adverse outcomes. Thus, to date, definitive evidence is largely awaited.
Hereby, the aim of this study was to perform a meta-analysis of randomized trials evaluating the clinical outcomes associated with IABC versus no IABC support in patients with AMI without CS.