Impact of timing of intraaortic balloon counterpulsation on mortality in cardiogenic shock- A subanalysis of the IABP-SHOCK II trial

Background: Conflicting results exist on whether initiation of intraaortic balloon pumping (IABP) before percutaneous coronary intervention (PCI) has an impact on outcome in this setting. Our aim was to assess the outcome of patients undergoing IABP insertion before versus after primary PCI in acute myocardial infarction complicated by cardiogenic shock. Methods: The IABP-SHOCK II-trial randomized 600 patients with acute myocardial infarction and cardiogenic shock to IABP-support versus control. We analysed the outcome of patients randomized to the intervention group regarding timing of IABP implantation before or after PCI. Results: Of 600 patients included in the IABP-SHOCK II trial, 301 were randomized to IABP-support. We analysed the 275 (91%) patients of this group undergoing primary PCI as revascularization strategy surviving the initial procedure. IABP insertion was performed before PCI in 33 (12%) and after PCI in 242 (88%) patients. There were no differences in baseline arterial lactate (p = 0.70), Simplified Acute Physiology Score-II-score (p = 0.60) and other relevant baseline characteristics. No differences were observed for short- A nd long-term mortality (pre vs. post 30-day mortality: 36% vs. 37%, odds ratio 0.99, 95% confidence interval (CI) 0.47-2.12, p = 0.99; one-year mortality: 56% vs. 48%, hazard ratio 1.08, 95% CI 0.65-1.80, p = 0.76; six-year-mortality: 64% vs. 65%, hazard ratio 1.00, 95% CI 0.63-1.60, p = 0.99). In multivariable Cox regression analysis timing of IABP-implantation was no predictor for long-term outcome (hazard ratio 1.08, 95% CI 0.66-1.78, p = 0.75). Conclusions: Timing of IABP-implantation pre or post primary PCI had no impact on outcome in patients with acute myocardial infarction complicated by cardiogenic shock.