Incidence of serum creatine kinase elevation and its relation to medications used after heart transplantation

Background: Rhabdomyolysis after heart transplantation is well described as a drug-related phenomenon. The incidence of serum creatine kinase (CK) elevation after heart transplantation is not formally reported in previous clinical studies. This study sought to find the incidence of asymptomatic serum CK elevation after heart transplantation and assess its relation to medications that are commonly used after transplantation. Methods: Data were collected in outpatient basis between August 2002 and August 2003. Patients with acute rejection, infection or muscle pain were excluded. All patients were followed monthly at a special clinic. Physical examinations and routine blood tests including serum CK were performed monthly. We evaluated the results of 106 asymptomatic patients and 765 serial data to determine the incidence of serum CK elevation after transplantation. Logistic regression was used to identify its risk factors. Results: The incidence of serum CK elevation in asymptomatic heart transplant recipients was 16.2%. Risk factors of its elevation were diabetes mellitus and use of medications including cyclosporine, drugs for hypertriglyceridemia, antihypertensives, and prednisolone. Among the antihypertensives commonly used, angiotensin converting enzyme inhibitors, angiotensin receptor blockers and calcium antagonists were associated with a higher incidence of serum CK elevation, but beta-blockers protected patients from serum CK elevation. Conclusion: The incidence of serum CK elevation in asymptomatic heart transplant recipients was not low. Serum CK measurements should be part of the routine follow-up in transplant recipients, especially when patients had diabetes mellitus. Medications commonly used after heart transplantation significantly affected the incidence of serum CK elevation.