Pulmonary arterial hypertension (PAH) is a progressive disease that often results in right ventricular (RV) failure and death. During
disease progression, structural and
electrical remodeling of the right ventricle impairs pump function, creates proarrhythmic substrates, and triggers for arrhythmias. Notably, RV failure and lethal arrhythmias are major contributors to
cardiac death in patients with PAH that are not directly addressed by currently available
therapies.
Ranolazine (RAN) is an antianginal, anti-ischemic drug that has cardioprotective effects in experimental and clinical settings of left-sided heart dysfunction. RAN also has antiarrhythmic effects due to inhibition of the late
sodium current in cardiomyocytes. We therefore hypothesized that RAN could reduce the maladaptive structural and
electrical remodeling of the right ventricle and could prevent triggered ventricular arrhythmias in the
monocrotaline rat model of PAH. Indeed, in both in vivo and ex vivo experimental settings, chronic RAN treatment reduced electrical heterogeneity (right ventricular-left ventricular action potential duration dispersion), shortened heart-rate corrected QT intervals in the right ventricle, and normalized RV dysfunction. Chronic RAN treatment also dose-dependently reduced ventricular
hypertrophy, reduced circulating levels of
B-type natriuretic peptide, and decreased the expression of fibrotic markers. In addition, the acute administration of RAN prevented
isoproterenol-induced
ventricular tachycardia/
ventricular fibrillation and subsequent cardiovascular death in rats with established PAH. These results support the notion that RAN can improve the electrical and functional properties of the right ventricle, highlighting its potential benefits in the setting of RV impairment.