Myocardial Perfusion Is Impaired and Relates to Cardiac Dysfunction in Patients With Atrial Fibrillation Both Before and After Successful Catheter Ablation

Abstract

BackgroundAtrial fibrillation (AF) is associated with myocardial infarction, and patients with AF and no obstructive coronary artery disease can present with symptoms and evidence of cardiac ischemia. We hypothesized that microvascular coronary dysfunction underlies these observations.Methods and ResultsMyocardial blood flow (MBF) at baseline and during adenosine stress and left ventricular and left atrial function were evaluated by magnetic resonance in 49 patients with AF (25 paroxysmal, 24 persistent) with no history of epicardial coronary artery disease or diabetes mellitus, before and 6 to 9 months after ablation. Findings were compared with those obtained in matched controls in sinus rhythm (n=25). Before ablation, patients with AF had impaired left atrial function and left ventricular ejection fraction and strain indices (all P<0.05 versus controls). MBF was impaired in patients both under baseline conditions (1.21±0.24 mL/min per g·[mm Hg·bpm/104]−1 versus 1.34±0.28 mL/min per g·[mm Hg·bpm/104]−1 in controls, P=0.044) and during adenosine stress (2.29±0.48 mL/min per g versus 2.73±0.37 mL/min per g in controls, P<0.001). Under baseline conditions, MBF correlated with left ventricular strain and left atrial function (all P≤0.001), so that cardiac function was most impaired in patients with the lowest MBF. Baseline and stress MBF remained unchanged postablation (both P=ns), and baseline MBF showed similar correlations with functional indices to those present preablation (all P≤0.001).ConclusionsBaseline and stress MBF are significantly impaired in patients with AF but no epicardial coronary artery disease. Reduction in MBF is proportional to severity of left ventricular and left atrial dysfunction, even after successful ablation. Coronary microvascular dysfunction may be a relevant pathophysiological mechanism in patients with a history of AF.

Left atrial 4D flow cardiovascular magnetic resonance: a reproducibility study in sinus rhythm and atrial fibrillation

“…At the baseline scan, the CMR protocol included retrospectively ECG-gated time-resolved balanced steady-state free precession (bSSFP) cine imaging in horizontal long axis (‘four-chamber’) and vertical long-axis (‘two-chamber’), for the evaluation of left ventricular (LV) ejection fraction (LVEF) and volumes, and LA emptying function (LAEF) and volumes as previously described [ 18 , 19 ]. All images were analysed using cvi42 software (version 5.3.4, Circle Cardiovascular Imaging Inc, Calgary, Alberta, Canada).…”

Impaired coronary blood flow at higher heart rates during atrial fibrillation: Investigation via multiscale modelling

“…Experimental data in humans demonstrated that the raise in myocardial blood flow accompanying AF may be insufficient to compensate for the increased cardiac workload due to the AF-related rise in heart rate, differently to what happens to the same hearts during atrial pacing at similar ventricular rate [10]. In addition to this reduction in coronary blood flow due to the irregularity of the RR intervals, a recent work [34] suggests that an underlying microvascular dysfunction, strictly related to left ventricular and left atrial mechanical dysfunction, may play a role in myocardial blood flow impairment in AF patients. In a similar context, the present computational framework focuses on the effects that different ventricular rates exert on the coronary circle during AF.…”

Mechanisms of atrial fibrillation

“…Longitudinal and multiparametric cardiac magnetic resonance studies show that even patients with apparently lone AF have significantly impaired ventricular myocardial energetics (figure 5), coronary microvascular dysfunction and subtle reduction in left ventricular performance, which fail to normalise following catheter ablation 32 46. This suggests that AF may actually be the consequence (rather than the cause) of an occult cardiomyopathy, which is unaffected by successful rhythm control, and that adjunctive therapies may be needed to target the ongoing drivers of the disease process.…”