The importance of the spatial QRS-T angle and its changes during inspiration for the diagnosis of pulmonary hypertension in patients with aortic stenosis

Introduction. Pulmonary hypertension (PH) in aortic stenosis (AS) worsens the prognosis. Vectorcardiographic parameters and functional tests can improve the informativeness of electrocardiography in detecting PH.

The aim of this study was to evaluate the potential of the spatial QRS-T angle (sQRS-Ta) and its changes during inspiration for diagnosing PH in patients with AS.

Materials and methods. The study included 170 patients with severe AS. Systolic pulmonary artery pressure (SPAP) was determined by echocardiography; sQRS-Ta was calculated as the spatial angle between the integral QRS and T vectors. Data are presented as median [Q25; Q75].

Results. SPAP was <45 mmHg in 138 (81%) patients and ≥45 mmHg in 32(19%) patients. Resting sQRS-Ta values had weak correlations with aortic valve area (r=- 0.3; p<0.0001), left atrium size (r=0.3; p<0.0001), and left ventricular myocardial mass index (r=0.3; p<0.0001). At SPAP<45 mmHg, inspiratory sQRS-Ta decreased (125° [95°; 150°] and 117° [86°; 142°], respectively, p<0.0001), while at SPAP≥45 mmHg it did not change (146° [106°; 158°] and 141° [101°; 163°], respectively, p=0.62). According to ROC analysis, both the resting sQRS-Ta (cutoff value > 151°, sensitivity 44%, specificity 78%) and the difference between inspiratory and resting sQRS-Ta (cutoff value ≤ 2°, sensitivity 63%, specificity 60%) allowed us to separate subgroups with SPAP ≥45 mmHg and <45 mmHg.

Conclusions. In patients with severe AS, inspiratory sQRS-Ta decreased with SPAP <45 mmHg, while it remained unchanged with SPAP ≥45 mmHg. Both the resting sQRS-Ta and the difference between inspiratory and resting sQRS-Ta allowed us to separate subgroups with SPAP ≥45 mmHg and <45 mmHg.

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