The Incidence, Pattern, and Prognostic Value of Left Ventricular Myocardial Scar by Late Gadolinium Enhancement in Patients With Atrial Fibrillation
What is the prevalence and clinical significance of left ventricular late gadolinium enhancement (LGE) in patients with atrial fibrillation?
This study examined 720 consecutive patients with atrial fibrillation who underwent cardiac magnetic resonance (CMR) imaging for atrial mapping prior to pulmonary vein ablation procedures, with additional analyses performed in a subset of 664 patients without known myocardial infarction (MI) based on medical history or electrocardiogram (n = 56). The prevalence and patterns of LGE were examined, and rates of all-cause mortality were compared between those with versus without LGE.
Mean age was 56 ± 11 years, and 73% were male. There were 68 deaths over a median follow-up of 42 months. In the overall population, LGE was observed in 108 individuals (15%), with ischemic and nonischemic patterns seen in 59% and 41%, respectively. In the subgroup of patients without known MI, LGE was identified in 88 cases (13%), with ischemic and nonischemic patterns each observed in 50% of individuals. In the 44 patients with no known MI and with an ischemic pattern of LGE on CMR, stress testing or coronary angiography was performed in 42 cases, and 18 patients underwent revascularization. In patients without known MI, the presence (hazard ratio [HR], 5.1; p < 0.001) and extent (HR, 1.2; p < 0.001) of LGE were associated with increased unadjusted mortality, regardless of LGE pattern, and these findings were also observed after additional exclusion of those with MI by LGE imaging (HR, 4.2 and 1.2, respectively; p < 0.001 for each). On multivariable analysis, variables independently associated with mortality in patients without known MI included age (HR, 1.1; p = 0.009) and extent of LGE (HR, 1.2; p < 0.001).
The authors concluded that LGE is often observed in patients with atrial fibrillation and no known history of MI, and is associated with increased all-cause mortality.
This study finds that LGE is not uncommon in patients referred for pulmonary vein ablation procedures for atrial fibrillation. After excluding patients with a known history of MI, 13% of individuals had LGE, and an ischemic pattern was noted in approximately one half of these patients. This builds on prior literature, which has identified an association between LGE and mortality in other populations, such as those with known ischemic heart disease and nonischemic cardiomyopathy. While there are inherent biases in this study—such as downstream stress testing or coronary angiography in nearly all patients with an ischemic pattern of LGE—the results suggest that the presence and pattern of LGE should be reported when readily available. However, it is unclear whether the addition of LGE imaging to standard imaging for atrial mapping impacts clinical outcomes, or whether the results have greater prognostic data as compared to alternative tests for atrial mapping, such as coronary artery assessment by cardiac computed tomography.
Keywords: Prognosis, Gadolinium, Magnetic Resonance Imaging
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