Con: Prophylactic preoperative use of an intra-aortic balloon pump is not indicated in high-risk coronary patients undergoing coronary artery bypass grafting.

HE PRIMARY EFFECT of the intra-aortic balloon pump (IABP) is to optimize the precarious balance between myocardial oxygen supply and demand, a vital component of the management of patients with coronary artery disease. Myocardial oxygen supply is improved through an enhancement of diastolic coronary blood flow and subendocardial perfusion, while a reduction in left ventricular afterload reduces oxygen demand. Whereas use of the IABP as a therapeutic intervention in patients with ongoing acute coronary syndromes and cardiogenic shock is of physiologic benefit, the prophylactic preoperative application of the IABP for high-risk hemodynamically stable patients undergoing coronary artery bypass surgery lacks a consensus. The authors hereby discuss, backed with evidence, the “con” side of prophylactic preoperative insertion of the IABP in hemodynamically stable high-risk patients undergoing coronary artery bypass grafting (CABG). A major counterpoint to the routine use of prophylactic IABP insertion in cardiac surgical patients is the lack of convincing evidence that it reduces mortality intraoperatively and postoperatively. In a large observational study, Holman et al evaluated the effects of pre-incision IABP insertion in high-risk, hemodynamically stable patients undergoing CABG, with regard to mortality and hospital length of stay. 1 Most importantly, this study excluded patients with recent or active coronary syndromes and patients with hemodynamic or pulmonary instability. Using propensity-matched analysis, the authors demonstrated that there were no significant differences between patients who received a prophylactic pre-incision IABP compared with those who did not or compared to those who received the IABP therapeutically intraoperatively and/or postoperatively. Interestingly, the former group experienced a significantly shorter hospital length of stay compared with the latter group. A similar lack of survival benefit was shown in a randomized controlled trial conducted by Metz et al. 2 In this study, the investigators performed prophylactic IABP placement in high-risk patients (defined by a EuroScore Z8) presenting for cardiac surgery with 30-day mortality as the primary endpoint assessed. Compared to the control group (no IABP), the group receiving prophylactic preoperative IABP did not demonstrate any reduction in 30-day mortality. Unlike the study conducted by Holman et al, 1 this study did not demonstrate any significant difference in hospital length of stay between the 2 groups (14 days in both groups). Additionally, there were no differences in cardiac indices, frequency of low-cardiac-output syndrome, catecholamine requirements, frequency of dialysis-dependent acute renal failure, or duration of postoperative mechanical ventilation. It is, therefore, conceivable that the prophylactic use of an IABP in high-risk cardiac surgical patients is not associated with meaningful effects on adverse outcomes. The prophylactic use of an IABP was not only associated with a lack of benefit, but its use also was associated with worse outcomes in some reports. Baskett et al 3 sought to elucidate the specific high-risk patient subgroup that would benefit most from prophylactic preoperative IABP placement prior to undergoing CABG surgery. This study looked at 7 high-risk clinical subgroups that included stable, unstable, urgent, and emergent patients. Even with an attempt to neutralize the preoperative IABP patient selection bias towards more critically ill patients by using multiple statistical comparative analyses and by excluding patients undergoing emergent surgery, the results showed that, in all patient subgroups, there was as ignificantly higher mortality associated with the use of a preoperative IABP. With that said, multiple unknown confounders might have conspired to bias the results of this analysis towards a higher mortality in patients with an IABP. Also, the definition of high-risk group was not consistent with previous similar reports. Perhaps the most convincing data come from a singlecenter prospective randomized cohort study conducted by Ranucci et al 4 that aimed to assess the benefit of preoperative IABP insertion. This trial analyzed hemodynamically stable high-risk patients (ejection fraction o0.35) undergoing nonemergent CABG surgery. Patients were assigned randomly to preoperative IABP placement or no preoperative IABP. The primary endpoint assessed, with relative risk analysis and adjusted odds ratio, was major morbidity defined by stroke, acute kidney injury, prolonged mechanical ventilation, wound infection, need for reoperation, and operative mortality. This study was halted prematurely secondary to a significant odds ratio for major morbidity after the second interim analysis. The authors concluded that stable patients undergoing nonemergent CABG did not benefit from the prophylactic use of an IABP. These studies reached vastly different conclusions from those of the widely cited study by Christenson and colleagues 5 in support of prophylactic use of an IABP. This latter study, however, included patients with active coronary syndromes and angina, tight left main coronary artery disease, and redo surgery; all were stronger indications for a therapeutic rather than a prophylactic use of an IABP. Inclusion of patients with a