Discussion
stroke, LV myocardial physiology, paroxysms
STROKE, CONTRACTION, DYSFUNCTION
Our findings demonstrate beneficial structural and functional alterations of the LA following AF ablation manifest by a recovery in LASct and improvement in LASres and LAScd, leading to a reduction in LA volumes and an increase in LAEF. There was no significant change in the parameters of LV diastolic function following ablation. From the pathophysiological perspective, the primary benefit of AF ablation is the regulation of cardiac rhythm from AF to SR leading to the recovery of LASct. These changes augment LA emptying, thereby reducing LA volume at the end of LA contraction allowing greater scope for LA recoil during LA filling and thus improving reservoir function. The regulation of cardiac rhythm leads to a constant stroke volume through the LA, and the reduction in the LAmin volume, facilitated by enhanced LA contraction, consequently leads to a reduction in LAmax volume. The LA volume reduction following ablation may also be related to scar-related contraction from ablation as seen in all our patients regardless of rhythm outcome, and the effects of underlying neurohormonal mechanisms.Approximately two-thirds of patients developed paroxysms of AF after the 3 months blanking period.As with LV myocardial physiology, the Frank-Starling mechanism also applies to the LA myocardium, such that as LA diameter and reservoir function increase, LA contractile function also increases, thereby maintaining stroke volume. However, in the presence of severe LA dilatation when the optimal pressure-volume relationship is exceeded, LA reservoir and contractile function might also decrease. It is well recognized that the longer the duration of AF, the more advanced the pathophysiological alterations leading to increasing LA dilatation and dysfunction.Cardiac magnetic resonance imaging and histopathology have shown a strong inverse correlation of LA fibrosis with LA strain in patients with persistent AF.