This was a retrospective, chart-review study of admissions or clinic visits to a university hospital between 2005 and 2010 by patients with a diagnosis of CKD. Inclusion criteria selected patients who had 12-lead surface electrocardiography (ECG), renal function tests within 24 hours, and transthoracic echocardiography within 6 months. Cases with a documented etiology for the corrected Qt (Qtc) interval prolongation including structural heart disease, QT prolonging drugs, or relevant disease conditions, were excluded.
Our sample size was 154 ECGs. Two-thirds of patients with CKD had QTc interval prolongation, and about 20% had a QTc interval greater than 500 ms. QTc interval was significantly different and increased with each successive stage of CKD using the Bazett (P less than 0.006) or Fridericia (P = 0.03) formula. QTc interval correlated significantly with serum creatinine (P = 0.01). These finding were independent of age, gender, potassium, and calcium concentrations.
The progression of CKD resulted in a significant delay of cardiac repolarization, independent of other risk factors. This effect may potentially increase the risk of sudden cardiac death, and may also increase the susceptibility of drug-induced arrhythmia.