Perioperative IABP in CABG Operations in Patients With Severely Depressed Left Ventricular Function: a Randomized, Controlled Trial

Since its first introduction in humans in 1962, Intra-Aortic Balloon Pump (IABP) is now the most commonly used therapeutic option to support failing heart in cardiac surgery. The main effects of IABP are an increase in diastolic blood pressure and therefore an improvement in coronary perfusion and a reduction of ventricular after load, thus increasing stroke volume and cardiac output. IABP-related complications include limb ischemia, bleeding at the site of IABP insertion, infection, and aortic dissection.

IABP could be used preoperatively, intraoperatively, or postoperatively. However, despite the wide use of the device, the optimal timing and use of IABP in high-risk patients undergoing cardiac surgery remains controversial. Time of insertion has been showed to affect hospital mortality, ranging from 18.8% to 19.6% for preoperative insertion, from 27.6% to 32.3% for intraoperative insertion, and from 39% to 40.5% for postoperative insertion. Several studies, randomized and non-randomized, have been conducted to address the impact of preoperative use of IABP on the outcome, each study including a relative small number of patients. In an effort to increase the strength of the results, two meta-analysis have been conducted and published in 2008. The objectives of both were to assess the effect on mortality and morbidity of using IABP preoperatively in high-risk patients undergoing coronary artery bypass grafting (CABG). Surprisingly, the meta-analysis from Field and co-workers was conducted on four randomized controlled trials (for a total of 193 patients included) published by the same author from the same institution, making the results not conclusive although favourable toward a beneficial effect of the preoperative use of IABP. Moreover, two of the randomized trials conducted by Christenson and co-workers and included in the above mentioned meta-analysis, were excluded from the meta-analysis from Dyub and co-workers because considered duplicates. Unfortunately, one study by Christenson and co-workers and included in the meta-analysis from Dyub was conducted on off-pump surgery, introducing another bias in the criteria of eligibility.

At present it is unclear whether the preoperative use of IABP in high-risk coronary patients scheduled for CABG operations leads to a better outcome. The experimental hypothesis of the present randomized, controlled trial (RCT) is that the placement of IABP immediately before beginning the surgical procedure induces a reduction of major morbidity after the operation.