Prognostic value of longitudinal QTc interval analysis in pulmonary arterial hypertension

In pulmonary arterial hypertension, the QTc interval prolongation has been associated with worse right ventricular adaptation to afterload and worse prognosis. It is not known whether the QTc interval is a modifiable parameter or if its changes at follow-up could provide prognostic information.

We retrospectively studied 213 PAH patients with at least two electrocardiograms during follow-up from January 2010 to March 2022. We analyzed the impact of the QTc interval and its changes between the first and last available electrocardiogram on survival rates.

Median age of 47.0 years (IQR: 37.8-61.0), 75 % were women. Idiopathic pulmonary hypertension was the leading PAH cause (46 %), followed by connective tissue disease-associated PAH (23.9 %). In the first evaluation, 26.7 % of patients had QTc prolongation, which normalized in 45.6 % of cases after a median follow-up of 4.3 years. 24.3 % of patients with a normal QTc at first evaluation had prolongation during follow-up. This subgroup had significantly higher levels of Nt-ProBNP, lower 6-min walk test distances, a higher proportion of individuals at high risk, and worse survival compared to those with consistently normal QTc (Log Rank <0.001) or who had prolonged QTc and normalization at follow-up (Log Rank 0.017). Prolonged QTc in the first evaluation was not associated with a worse prognosis, while QTc prolongation during follow-up was an independent predictor of mortality HR: 5.5 (1.72-17.64).

The QTc interval is a potentially modifiable variable, and its longitudinal assessment can identify different risk profiles. Its prolongation during follow-up is associated with higher mortality.