Influence of length of aortic occlusion with cold potassium cardioplegia on early and late mortality in cardiac valve replacement

This study determines if prolonged aortic crossclamp time (ACC) with the use of cold potassium cardioplegia during elective cardiac valve replacement contributed to the risk of operative mortality in 225 patients. In Group I (143 patients), the ACC was < 120 minutes (mean 86) and in Group II (82 patients), it was > 120 minutes (mean 146). The preoperative variables showed that Group II contained more severely ill patients who were undergoing more complex operations than in Group I. The operative mortality rate was 7% in Group I and 10% in Group II (p = not significant). Postoperative inotropic support was required in 13% of Group I and 30% of Group II patients (p < 0.005). Operative mortality in patients in New York Heart Association (NYHA) functional class I and II was 0 and in patients in classes III and IV it was 13% (p < 0.00008). Five percent of patients in NYHA classes I and II and 32% in classes III and IV required inotropic support (p < 0.000005). The actuarial survival at 60 months was 88 ± 3% for Group I and 77 ± 7% for Group II (NS). For the NYHA class I and II patients, however, it was significantly better (98 ± 2%) than class III and IV patients (75 ± 5%) (p < 0.0001). Analysis by logistic equation revealed that the NYHA functional classes III and IV were significant incremental risk factors for probability of in-hospital mortality (p < 0.0001) but not the ACC time (p > 0.1). Thus, the preexisting severity of disease (for example, NYHA class), rather than the length of ACC, influences the early mortality and the late survival. However, ACC > 120 minutes may contribute to cardiogenic depression in the early postoperative period.