Poor left-ventricular function, hypertension, and left-ventricular hypertrophy in patients with coronary artery disease (CAD) undergoing coronary artery bypass grafting (CABG) are associated with increased operative risks. Between June 1994 and March 1996, 33 patients undergoing CABG, were randomized into 2 groups. One group (IABP group, n = 19) received IABP treatment on average for 2 hours prior to CPB, the other group (control group, n = 14) had no preoperative IABP, Cardiac performance was measured pre- and postoperatively by Swan-Ganz catheter. Mean age was 65 years and 90% were men. All patients had a preoperative LVEF < or = 40% (mean 32.6 +/- 11.1%), 3-vessel disease, established hypertension (WHO criteria), and LV hypertrophy (ventricular mass > or = 136 g/m2 [men] or > or = 110 g/m2 [women]). Ischemia time was similar in both groups while CPB-time was shorter in the IABP group, p < 0.05. There were no hospital deaths in the IABP group, but 3 in the control group suffered postoperative low cardiac output. Nine patients (64%) in the control group required IABP support postoperatively, but only 20% of the patients in the IABP group had a shorter ICU stay, 2.4 +/- 0.9 vs. 3.4 +/- 1.1 days, p < 0.01. Cardiac index increased significantly in the IABP group prior to CPB and was higher compared to control, p < 0.001. Five min after CBP cardiac index was higher in the IABP group than in the control group, p = 0.013, and continued to increase thereafter, while no further improvement was observed in controls. Preoperative IABP treatment in hypertensive patients with CAD, low LVEF and LV hypertrophy who are undergoing CABG is beneficial. An improved cardiac performance pre- and postoperatively was associated with a lower rate of hospital mortality and less postoperative morbidity, as well as shorter ICU stay. The treatment is cost-beneficial.