The Prognostic Value of Cardiac Axis Deviation in Systemic Sclerosis-related Pulmonary Hypertension.

OBJECTIVE Systemic sclerosis-related pulmonary hypertension (SSc-PH) is a common complication of SSc associated with accelerated mortality. We hypothesized that cardiac axis deviation may indicate abnormalities in cardiac function allowing for prognostication of disease severity and mortality. METHODS This was a retrospective study where electrocardiograms (ECGs) were reviewed for cardiac axis deviation and their association with echocardiography and cardiopulmonary hemodynamics on right heart catheterization. The primary outcome observed was all-cause mortality from the time of PH diagnosis. RESULTS ECGs were reviewed from 169 patients with SSc-PH. Right axis deviation (RAD) and left axis deviation (LAD) occurred in 28.4% and 30.8% of patients with SSc-PH, respectively. Compared to those without, patients with RAD exhibited predominantly right-sided cardiac disease on echocardiography and increased PH severity by cardiopulmonary hemodynamics including a greater mean pulmonary artery pressure (42.0 ± 12.5 mm Hg vs. 29.8 ± 7.0 mm Hg) and pulmonary vascular resistance (645.6 ± 443.2 dyn·s/cm5 vs. 286.3 ± 167.7 dyn·s/cm5 ). LAD was associated with predominantly left-sided cardiac disease on echocardiography but was not associated with PH severity on cardiopulmonary hemodynamics. Both RAD (HR: 10.36; 95% CI: 4.90 - 21.93; p < 0.001) and LAD (HR: 2.94; 95% CI: 1.53 - 5.68; p = 0.001) were associated with an increased hazard for all-cause mortality. CONCLUSION RAD and LAD reflect structural cardiac abnormalities and are associated with poor prognosis in patients with SSc-PH. These findings support the importance of electrocardiography, an inexpensive, widely available non-invasive test, in risk stratification.