Riluzole Provides Insights into the Mechanisms of Ischaemic and Ischaemia-reperfusion Arrhythmias

Abstract

Introduction: Primary pulmonary hypertension (PPH) is associated with RVH and RA enlargement. Little is known of the direct atrial effects of chronic stretch due to ventricular hypertrophy in humans. We performed electrophysiologic (EP) and electroanatomic (EA) RA studies in pts with PPH and RVH without atrial arrhythmias. Methods: 18 pts with (age: 52± 19 y) and without (age: 43± 14 y p= 0.3) PPHunderwent detailed EP and EAmapping. We measured atrial ERP, SNRT, conduction times (CT) and velocities (CV), regional low voltage and scar (bipolar voltage < 0.5mV and< 0.05mV, respectively) and serum markers of collagen turnover(P1NP). Results: (Table) PPH was associated with increased: RA pressure(4± 2 vs. 1± 1 in controls, p= 0.03); RVSP (61± 9mmHgvs. 23± 2mmHg in controls,p< 0.001). PPH wasassociatedwithprolongationofERPandSNRT, reduction in mean voltage, regional low voltage and atrial scarring together with slowing of global and regional conduction. Collagen turnover was increased in PPH (P1NP 171± 284 vs. controls 56± 39, p= 0.1). Conclusions: RVH secondary to PPH is associated with atrial remodelling characterised by (i) ERP prolongation, (ii) diffuse conduction slowing with evidence of marked regional abnormalities (iii) reduced tissue voltage and frank scar. These changes may in part be responsible for the increased propensity to AA’s observed with chronic atrial stretch secondary to ventricular hypertrophy.