Predicting cardiac index using the electrocardiogram in pulmonary hypertension patients

Background: Pulmonary hypertension (PH) is a fatal disease where on-time treatment can change the prognosis. The selection of treatment is dictated by the severity of PH. The cardiac index (CI) is a robust indicator of PH severity. This trial aimed to find out the association between electrocardiogram (ECG) data and CI as a prognostic factor of PH. Methods: Ninety-five patients with precapillary PH were included in the study. The cardiac output of patients was calculated using the right heart catheterization and the Fick formula. Patients were categorized into low- and high-risk groups based on the CI. Their ECGs were interpreted by an expert cardiologist. The association between ECG parameters and severity of PH was evaluated based on the CI. Results: The median age of patients was 36 years. The mean of CI was 2.35 L/min/m2 with a standard deviation of 0.74. About 36% of patients were in the high-risk category based on the CI. Among ECG parameters, ST segment depression in V1-V6 and R/S ratio ≥1 in V1 were found significantly correlated with CI for high-risk category (P = 0.026). Conclusion: ST segment depression in V1-V6 and R/S ratio ≥1 in V1 had a significant association with CI in the range lower than 2 L/min/m2, which is an indicator of poor PH prognosis. Therefore, these variables can be used as an inexpensive and available prognostic factor in patients with precapillary PH.