The potential use of the ECG for monitoring treatment effects in patients with pulmonary arterial hypertension (PAH) has not been investigated. We evaluated whether the ECG is useful for monitoring treatment response based on changes in pulmonary vascular resistance (PVR).
An ECG was recorded in 81 PAH patients at the time of diagnostic right heart catheterization and after 1 year of treatment. Patients were treated according to the guidelines. Patients were divided into two groups based on PVR (ie, < 500 or > 500 dyne · s · cm–5). A positive treatment response was defined as a > 25% decrease in PVR to an absolute PVR of < 500 dyne · s · cm–5.
At baseline, the 19 patients with a PVR of < 500 dyne · s · cm–5 had a significantly lower P amplitude in lead II, a less rightward oriented QRS axis, and a more rightward T axis than the 62 patients with a PVR of > 500 dyne · s · cm–5. Overall (n = 81), the mean (± SD) change in PVR was −143 ± 360 dyne · s · cm–5 after 1 year of treatment (p < 0.001). Twelve patients (19%) with a baseline PVR of > 500 dyne · s · cm–5 were classified as responders. Receiver operating characteristic analysis determined that the P amplitude in lead II (area under the curve [AUC], 0.80; 95% confidence interval [CI], 0.67 to 0.94; p < 0.01), QRS axis (AUC, 0.70; 95% CI, 0.52 to 0.89; p = 0.03), and T axis (AUC, 0.90; 95% CI, 0.82 to 0.97; p < 0.001) were important determinants of treatment response. The presence of a P amplitude in lead II of < 0.175 mV and a T axis of ≥ 25° combined had a positive and negative predictive value for treatment response of 0.81 (95% CI, 0.37 to 0.96) and 0.94 (95% CI, 0.86 to 0.99), respectively.
Routine ECG evaluation can be an important contribution in the assessment of treatment response in PAH patients.