St. Thomasʹ Hospital cardioplegia: Enhanced protection with exogenous creatine phosphate

Background. Experimentally, creatine phosphate (CP) improves postischemic recovery of function and reduces postischemic arrhythmias. Methods. We studied 50 patients undergoing valve replacement. They were randomized into either a control group, who received St. Thomasʹ Hospital cardioplegic solution No. 1, or a CP-treated group, receiving the same cardioplegic solution plus CP (10 mmol/L). There were no preoperative clinical differences between groups. Assessment was by electrocardiographic analysis, inotropic drug requirement, quantitative birefringence, myocardial high-energy phosphate content, function, and semi-quantitative ultrastructural assessment. Results. Direct-current shocks were reduced in the CP-treated group (0.88 ± 0.15) compared with the control group (1.40 ± 0.14; p < 0.02), as was the total number of joules (22.0 ± 3.5 versus 34.4 ± 3.7, respectively; p < 0.02). The incidence of spontaneous sinus rhythm was higher in the CP-treated group (40% versus 8%; p < 0.05) and the incidence of postoperative arrhythmias, lower (8% versus 32%; p < 0.05). Prolonged inotropic administration (12 hours or longer) occurred in fewer patients in the CP-treated group (4% versus 28%; p < 0.05). Response to inotropic support (in the subset of patients requiring this treatment) was significantly greater in the CP-treated group than in the control group. There were no differences in recovery of function, birefringence changes, myocardial high-energy phosphate content, or ultrastructure between groups. Conclusions. St. Thomasʹ Hospital cardioplegic solution No. 1 plus CP enhanced myocardial protection and conferred a direct benefit to the patient by reducing postoperative arrhythmias and need of prolonged inotropic support.