Is Conduction Disease More Prevalent in Idiopathic Pulmonary Hypertension?

Patients with idiopathic pulmonary hypertension (IPAH) have a higher prevalence of conduction disease than patients without IPAH, according to recent study results published in the Journal of Heart and Lung Transplantation. The study confirmed that IPAH patients with conduction disorder have reduced physical functioning and a poor prognosis, typically resulting in right ventricular (RV) failure and death.

Clinicians have suspected that IPAH, characterized by raised pulmonary vascular resistance, could lead to conduction disorder, but a dearth of research exists on the subject. Investigators based in Cambridge in the United Kingdom sought to find out the prevalence of disordered cardiac conduction in IPAH patients and how the condition affects patient function.

The researchers performed an observational cohort study of 175 patients, retrospectively comparing the electrocardiograms of IPAH patients (N=65) with those not having IPAH (N=110) to ascertain the rate of conduction disease in both groups.

The cohort with conduction disease was 44.6% male, compared with 23.6% male in the control group (adjusted P =.015) and aged 62 ± 16 years, compared with 53 ± 17 years in the control group (adjusted P =.003).

The investigators found that 37.1% of patients in the IPAH group had developed conduction disease, compared with 10.8% of the control group (P <.001). Right bundle branch block was the most common type seen in the IPAH cohort.

The right heart ventricle of patients with conduction disease displayed increased dilatation compared with controls (RV basal diameter 5.2 vs 4.5cm, adjusted P =.01; right atrium volume 109.4 vs 70.8cm₃, adjusted P =.019). N-terminal-pro hormone BNP levels also were higher (851 compared with 207, adjusted P  =.002).

The functional capability of patients in the conduction disease group was reduced compared with those in the control cohort, as evidenced by lower 6-minute walk distances and higher Cambridge Pulmonary Hypertension Outcome Review (CAMPHOR) scores in activity, symptom perception, and quality of life.

Findings also revealed that mortality was higher in the conduction disease cohort, occurring roughly 10 years following the diagnosis of IPAH.

During the median follow-up period of 6.9 (2.8-12.7) years, 11 patients who initially displayed normal heart conduction developed disordered conduction (mean age at onset 62 ± 14 years, 2 [18.2%] male), and 3 of the 11 (27.3%) died.

“More detailed investigation into causal mechanisms of conduction disease in IPAH, and whether restoration of prognosis and functionality could be achieved by treatment of conduction disease, would be of great interest,” the authors wrote. “Early screening for conduction disease may…have substantial downstream prognostic implications,” they added.

Reference

Reddy SA, Nethercott SL, Teh W, et al. Prevalence and clinical significance of conduction disease in patients with idiopathic pulmonary arterial hypertension. J Heart Lung Transplant. Published online April 7, 2022. doi:10.1016/j.healun.2022.03.024