Purpose: To implement a cardiac magnetic resonance (CMR)-based protocol to define atrial structure and function in individuals with paroxysmal atrial fibrillation (PAF), heritable cardiac conduction and myocardial disease with atrial dysrhtyhmias (HCCMD), and healthy controls.
Methods: Fifteen controls, 20 PAF, and 12 HCCMD subjects underwent CMR examination including: multislice short-axis cine, multislice horizontal long-axis cine, and gadolinium-enhanced coronal plane magnetic resonance angiography (MRA) for pulmonary vein analysis. We also assessed for ventricular myopathy with delayed myocardial enhancement (DME) acquisitions.
Results: Right and left ventricular measurements did not differ among the three groups. Seven heritable atrial dysrhythmia subjects and no control or PAF subjects demonstrated midmyocardial fibrosis of the basal interventricular septum by DME. Left atrial (LA) volume at the onset of atrial systole and minimal LA volume were significantly higher in PAF subjects compared to controls (p < 0.05 for both), LA percent emptying was significantly lower in PAF subjects (p < 0.01), and RA percent emptying was significantly lower in PAF subjects compared to controls (p < 0.01), though these differences were not significant when controlling for heart rate, age and gender. There was no significant difference in right atrial (RA) volumes among study groups. Atrial volumes and function did not differ significantly between heritable atrial dysrhtyhmia subjects and controls. PAF subjects had greater frequency of a right middle pulmonary vein (RMPV) than controls (6/20 vs. 3/15) that did not reach statistical significance.
Conclusions: CMR can quantify atrial structure and function in patients with PAF compared to controls. This protocol could not detect abnormalities in atrial function in early affected patients with heritable cardiomyopathy and atrial premature beats.