St. Thomas' 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. Thomas' 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 semiquantitative 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. Thomas' 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.