Late Gadolinium Enhancement CMR in Hypertrophic Cardiomyopathy Risk Stratification | Journal Scan
In patients with hypertrophic cardiomyopathy (HCM), is myocardial fibrosis seen on late gadolinium enhancement (LGE) cardiac magnetic resonance imaging (CMR) an independent risk factor for sudden cardiac death (SCD)?
The authors conducted a prospective observational cohort study of 815 patients at a single tertiary referral center followed over a median of 3.5 years. Patients were excluded if they had prior myomectomy or alcohol septal ablation, prior myocardial infarction, contraindications to contrast-enhanced CMR, withdrew consent, or were lost to follow-up for a final study cohort of 711 patients. CMRs were performed using 1.5 T MRI scanners. The primary outcome was SCD or aborted SCD.
Nearly two thirds of patients had myocardial fibrosis (n = 471). Overall, 22 patients (3.1%) experienced the primary endpoint of SCD or aborted SCD; 18 in the group with fibrosis and 4 in the group without. Although the amount of fibrosis was a significant predictor of the primary outcome on a univariable basis (hazard ratio of 1.24 per 5% of the myocardium), on multivariable analysis, only left ventricular ejection fraction (LVEF) was an independent predictor. Similar results were obtained for the secondary outcome of cardiovascular death or aborted SCD.
Although the amount of myocardial fibrosis on LGE CMR was a strong univariable predictor of SCD risk, this did not persist after adjustment for LVEF.
This study, performed in a large cohort with modern MRI techniques by a very capable group, has significant implications for the management of patients with HCM. Prior studies had shown that LGE was a strong predictor of SCD risk (generally on a univariable basis), arguing for a role of LGE in selection of patients for implantable cardioverter-defibrillator implantation. However, in this large study adequately powered for multivariable adjustment, after LVEF was accounted for, there was no additional value to the presence or extent of fibrosis on CMR in identifying SCD risk. This suggests that although focal or regional fibrosis may be mechanistically connected to SCD in HCM, other factors may also play an important role, and LVEF as a marker of disease stage is the most powerful predictor and warrants greater emphasis in clinical guidelines.
Keywords: Cardiomyopathy, Hypertrophic, Cardiomyopathies, Magnetic Resonance Imaging, Gadolinium, Risk Factors, Myocardium, Stroke Volume, Prospective Studies, Heart Failure, Tertiary Care Centers
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