Electrocardiographic changes in patients responding to treatment with group i pulmonary arterial hypertension

BACKGROUND: Various changes in conductivity as reflected in the electrocardiogram (ECG) have been associated with the onset and progression of pulmonary arterial hypertension (PAH). Little data exist as to whether the ECG can be used to identify patients responding to treatment. METHODS: A retrospective chart review of patients diagnosed by right-sided cardiac catheterization as having group I PAH within the past 5 years was performed. A total of 121 patients were reviewed, of whom 36 were found to be responders to treatment and were included in our study. Patients were defined as responders by evidence of symptomatic improvement and decrease in right ventricular systolic pressure by at least 15%. RESULTS: Of 36 patients included, the majority were women (n = 26, 72%) with an average age of 59.6 years. Significant differences in right-sided heart pressures based on echocardiogram were noted between the pretreatment and posttreatment subsets, with a decrease in right atrial pressure from 12.7 to 7.6 mm Hg (P = 0.0035), right ventricular systolic pressure from 83.2 to 55.3 mm Hg (P < 0.0001), and estimated pulmonary arterial mean pressure from 53.8 to 38.9 mm Hg (P < 0.0001). Electrocardiographic parameters, including resting heart rate (80 vs 76 bpm; P = 0.3683), QRS duration (98 vs 99 msec; P = 0.8444), calculated QT interval (461 vs 454 msec; P = 0.4386), premature ventricular contractions (n = 0 vs 2; P = 0.1558), right axis deviation (n = 14 versus 14; P = 1.00), right bundle branch block (n = 13 vs 7; P = 0.1176), and various measurements of right ventricular hypertrophy showed no difference. CONCLUSIONS: Although the ECG may be useful in helping to evaluate the onset and progression of PAH, its utility is limited in assessing appropriate response to treatment in this patient population.