The Correlation between QT Dispersion and Severity of Pulmonary Valve Stenosis

Abstract
Background: The heart rate-corrected QT interval (QTc) and QTc dispersion (QTcd) are prolonged and associated with ventricular arrhythmia and an increase in sudden death in a variety of diseases such as coronary heart disease, heart failure, hypertension and diabetes mellitus.
Objective: Study of the relation between QTcd, QT interval and QTc and severity of pulmonary stenosis.
Methods: A prospective observational cohort single center study in a period of 10 months starting from June 2016 to March 2017 at Cardiovascular Medicine Department, Tanta University Hospitals in Gharbia Governorate, Egypt. The study enrolled 50 subjects of both genders; 40 patients who were diagnosed with pulmonary stenosis & 10 subjects matched in age, sex, weight and body surface area as a control group. Resting 12-lead electrocardiogram was recorded. QT interval was measured manually and corrected using Bazett's formula. Patients were divided into groups with mild, moderate and severe pulmonary valve stenosis and a control group according to peak pressure gradient across pulmonary valve.
Results: In all observed cases, mean QTc was higher in severe pulmonary valve stenosis than in controls (448.67±28.0 ms vs. 404.0±19.55ms, p=0.001) and QTcd was higher in mild, moderate (51.75±2.18 & 69.23±6.07ms respectively) and severe pulmonary valve stenosis (79.27±6.73ms) than in controls (46.20±5.49ms) (p=0.001).
Conclusion: In patients with pulmonary valve stenosis, mean QTc and QTcd are positively correlated to peak pressure gradient across pulmonary valve and are significantly increased in patients with severe pulmonary valve stenosis.