Nifedipine cardioplegia experience: results of a 3-year cooperative clinical study

Previous animal studies and a preliminary clinical trial of the addition of nifedipine to cardioplegic solution demonstrated salutary effects in terms of postischemic performance. This report examines the combined results of extended clinical trials conducted in two centers: Barnes Hospital, St. Louis, and Allegheny General Hospital, Pittsburgh. From an open-heart population of 4,777 patients, 205 highest-risk persons were selected for study. One hundred seventy of them were given nifedipine in cardioplegic solution. The remaining 35 served as controls to compare with 39 treated patients in the randomized subset of 74. Thirty-eight percent were women; the average age was 61 +/- 1 year; and most were in New York Heart Association Class IV. One-third had valve replacement, one-quarter had coronary artery bypass grafting (CABG), and 37% had valve, CABG, and other procedures in combination. Characteristically, these patients had a 50% increase in end-diastolic volumes, low cardiac indexes (1.7 +/- 1 L/min/m2), and low left ventricular stroke work indexes (22 +/- 2 gm-m/m2). Average cross-clamp time was 77 minutes. At Allegheny, an extracellular hyperkalemic solution was used to deliver an average dose of 407 +/- 22 micrograms per patient. At Barnes, a low-sodium hyperkalemic solution was used; the average dose was 476 +/- 22 micrograms. The results of hemodynamic studies in the randomized subset demonstrated approximately a twofold greater improvement in the treated group in cardiac index, stroke volume, left ventricular stroke work index, and pulmonary vascular resistance immediately after bypass. The incidence of acute low cardiac output death was 4% versus 11% in the nontreated group. The hospital survivorship for all treated patients was 84%. It is concluded that the addition of a calcium antagonist, nifedipine, reduced the incidence of acute global cardiac failure in the immediate postoperative interval.