Heart rate-corrected QT interval and QT dispersion in patients with pulmonary hypertension
OBJECTIVE: Heart rate-corrected QT interval (QTc) and QTc dispersion (QTcd) are increased and associated with ventricular arrhythmia and an increase in sudden death in a variety of diseases. This study aimed to examine QTc and QTcd in pulmonary hypertension and assess their relationship with pulmonary arterial pressure. PATIENTS AND METHODS: A total of 201 patients who had undergone right heart catheterization for a preliminary diagnosis of pulmonary hypertension between December 2003 and July 2008 were included in the study. Resting 12-lead electrocardiogram was recorded. QT interval was measured manually and corrected using Bazett's formula. Patients were divided into groups with mild-to-moderate and severe pulmonary hypertension and a control group according to mean pulmonary arterial pressure. RESULTS: In all observed cases, mean QTc was higher in severe pulmonary hypertension than in controls (428.6 ± 32.8 ms vs. 411.1 ± 28.4 ms, P = 0.018) and QTcd was higher in mild-to-moderate (60.1 ± 17.2 ms) and severe pulmonary hypertension (63.9 ± 20.5 ms) than in controls (47.3 ± 10.6 ms) (P = 0.031; P = 0.004). In men, there was no significant difference in mean QTc and QTcd. In women, mean QTc was higher in severe pulmonary hypertension than in controls (436.1 ± 39.4 ms vs. 407.6 ± 24.8 ms, P = 0.037) and QTcd was higher in severe pulmonary hypertension (68.5 ± 20.9 ms) than in both the controls (45.1 ± 12.6 ms) and patients with mild-to-moderate pulmonary hypertension (58.6 ± 14.7ms) (P = 0.002; P = 0.003). In addition, in women with pulmonary hypertension, mean QTc and QTcd were positively correlated to mean pulmonary arterial pressure (r = 0.207, P = 0.03; r = 0.236, P = 0.012). CONCLUSIONS: In women with pulmonary hypertension, mean QTc and QTcd are positively correlated to mean pulmonary arterial pressure and are significantly increased in patients with severe pulmonary hypertension.