Change in the electrical axis of the heart during inspiration as an additional sign of the presence of pulmonary hypertension in patients with aortic stenosis

The aim of the study was to evaluate the possibility of using an inspiratory electrocardiogram to detect pulmonary hypertension (PH) in patients with severe aortic stenosis (AS). Materials and methods. The study included 166 patients with severe AS aged 73±8 years. Pulmonary artery systolic pressure (PASP) was determined by echocardiography. The position of the heart electrical axis (HEA) was assessed during quiet breathing (HEAq) and deep inspiration (HEAin). Results. In 93 (56%) patients, PASP was <35 mmHg, in 45 (27%) from 35 to 44 mmHg, and in 28 (17%) patients ≥45 mmHg. In groups with PASP<45 mmHg, on inspiration, there was a shift in the HEA to the right of the initial value (p<0.0001), and at PASP ≥45 mm Hg, these changes did not reach statistical significance (p = 0.05). In the ROC analysis, the HEAq, HEAin, and the difference between them made it possible to separate the groups of patients with PASP<35 mm Hg and ≥35 mm Hg. The optimal threshold values were HEAq ≤-19° (sensitivity 34%, specificity 85%), HEAin ≤16° (sensitivity 49%, specificity 76%), and the difference between HEAin and HEAq <18° (sensitivity 70%, specificity 66%). Only the difference between the HEAq and HEAin with an optimal threshold value of <16° (sensitivity 79%, specificity 60%) allowed us to separate the groups of patients with PASP<45 mm Hg and ≥45 mm Hg. Conclusions. In patients with severe AS, there is a shift of the HEA to the right from the initial value during inhalation, which is most pronounced in patients without PH. A lesser degree of shift of the HEA to the right from the initial value during inhalation allowed us to distinguish both the patients with PASP ≥35 mmHg and ≥45 mmHg with a sensitivity of 70-79% and a specificity of 60-66%.