Relationship Between Right Ventricular Function and Chronotropic Incompetence in Pulmonary Arterial Hypertension Associated With Connective Tissue Disease.

BACKGROUND

Pulmonary arterial hypertension associated with connective tissue disease (CTD-PAH) is a progressive disease characterized by remodeling of the pulmonary vasculature, leading to increased right ventricular (RV) afterload and impaired exercise capacity.

RESEARCH QUESTION: The impact of RV dysfunction on chronotropic response remains poorly understood in patients with CTD-PAH.

STUDY DESIGN AND

METHODS

This observational cohort study was conducted at our institution between April 2022 and March 2025. We enrolled 89 consecutive patients with CTD-PAH; 22 patients were excluded because of beta-blocker use (n = 9) or inability to exercise (n = 13). A total of 67 patients underwent echocardiography and exercise-stress right heart catheterization. Patients were classified into a preserved RV function group (tricuspid annular plane systolic excursion/systolic pulmonary arterial pressure, ≥ 0.55; n = 47) and an impaired RV function group (tricuspid annular plane systolic excursion/systolic pulmonary arterial pressure, < 0.55; n = 20); clinical parameters and outcomes were compared. Chronotropic incompetence was defined as peak heart rate (HR) < 85% of age-predicted HR and < 80% chronotropic response index: (maximum HR - resting HR)/(220 - age - resting HR).

RESULTS

Chronotropic incompetence affected 94% of patients. Age, sex, body size, BP, and left ventricular ejection fraction were comparable between the 2 groups. Compared with the preserved RV group, the impaired RV group had a lower chronotropic response index (preserved vs impaired RV group: 47.1% ± 20.3% vs 35.6% ± 14.8%; P = .034), lower delta HR/resting HR (0.56 ± 0.26 vs 0.36 ± 0.14; P = 0.003), lower mixed venous oxygen at rest (74.4% ± 3.7% vs 70.1% ± 7.0%; P = .004), lower peak oxygen consumption (517.1 ± 202.3 vs 402.2 ± 153.1 mL/min; P = .024), and higher peak pulmonary vascular resistance (2.2 ± 1.3 vs 3.5 ± 2.1 Wood units; P = .013).

INTERPRETATION: Chronotropic incompetence was observed in 94% of patients with CTD-PAH. RV dysfunction was associated with worse chronotropic response and contributed to reduced exercise capacity.