Vectorelectrocardiographic marker of right ventricular enlargement and its changes during inspiration in patients with precapillary pulmonary hypertension

Introduction. Timely diagnosis of pulmonary hypertension (PH) is important for disease prognosis. The use of computational vector electrocardiography (vECG) and functional testing can facilitate earlier detection of PH. The aim of this study was to evaluate vECG parameters reflecting right ventricular enlargement in patients with precapillary PH during quiet breathing and deep inspiration and to compare the results with structural and functional characteristics of the heart using echocardiography. Materials and Methods. The study included 80 patients with idiopathic PH and chronic thromboembolic PH. Echocardiography assessed cardiac chamber size, ventricular systolic and diastolic function, pulmonary artery pressure, and pulmonary vascular resistance (PVR). The vECG parameter used was the proportion of the QRS loop area in the right quadrants to the total QRS loop area in the horizontal plane (%SQRSxz). Results. The %SQRSxz values during quiet breathing were 49±23%, while during inspiration they were 55±23% (p< 0.0001). During inspiration, %SQRSxz increased in 72.5% of patients, decreased in 22.5%, and remained unchanged in 5%. Moderate direct correlations were found between %SQRSxz and right atrial and right ventricular dimensions, eccentricity index, pulmonary artery pressure, and PVR, as well as inverse correlations with right ventricular systolic function, stroke volume, and cardiac output. Patients with decreased %SQRSxz during inspiration had higher right ventricular anterior wall thickness, eccentricity index, pulmonary artery pressure, and PVR, and worse right ventricular systolic and diastolic function, and were more likely to have severe tricuspid regurgitation and pericardial effusion. Conclusion. In patients with precapillary pulmonary hypertension, %SQRSxz and its changes during inspiration correlated with echocardiographic parameters and reflected not only the presence of right ventricular enlargement but also its severity. further studies of the potential of vECG in assessing patients with pulmonary hypertension appear promising.