OBJECTIVES: We sought to evaluate the relation between atrial fibrillation (AF) 
and the extent of myocardial scarring together with left ventricular (LV) and 
atrial parameters assessed by late gadolinium-enhancement (LGE) cardiovascular 
magnetic resonance (CMR) in patients with hypertrophic cardiomyopathy (HCM).
BACKGROUND: AF is the most common arrhythmia in HCM. Myocardial scarring is also 
identified frequently in HCM. However, the impact of myocardial scarring 
assessed by LGE CMR on the presence of AF has not been evaluated yet.
METHODS: 87 HCM patients underwent LGE CMR, echocardiography and regular ECG 
recordings. LV function, volumes, myocardial thickness, left atrial (LA) volume 
and the extent of LGE, were assessed using CMR and correlated to AF. 
Additionally, the presence of diastolic dysfunction and mitral regurgitation 
were obtained by echocardiography and also correlated to AF.
RESULTS: Episodes of AF were documented in 37 patients (42%). Indexed LV volumes 
and mass were comparable between HCM patients with and without AF. However, 
indexed LA volume was significantly higher in HCM patients with AF than in HCM 
patients without AF (68 +/- 24 ml.m-2 versus 46 +/- 18 ml.m-2, p = 0.0002, 
respectively). The mean extent of LGE was higher in HCM patients with AF than 
those without AF (12.4 +/- 14.5% versus 6.0 +/- 8.6%, p = 0.02). When adjusting 
for age, gender and LV mass, LGE and indexed LA volume significantly correlated 
to AF (r = 0.34, p = 0.02 and r = 0.42, p < 0.001 respectively). By 
echocardiographic examination, LV diastolic dysfunction was evident in 35 (40%) 
patients. Mitral regurgitation greater than II was observed in 12 patients 
(14%). Multivariate analysis demonstrated that LA volume and presence of 
diastolic dysfunction were the only independent determinant of AF in HCM 
patients (p = 0.006, p = 0.01 respectively). Receiver operating characteristic 
curve analysis indicated good predictive performance of LA volume and LGE (AUC = 
0.74 and 0.64 respectively) with respect to AF.
CONCLUSION: HCM patients with AF display significantly more LGE than HCM 
patients without AF. However, the extent of LGE is inferior to the LA size for 
predicting AF prevalence. LA dilation is the strongest determinant of AF in HCM 
patients, and is related to the extent of LGE in the LV, irrespective of LV 
mass.