Background: In hypertrophic cardiomyopathy (HCM), the arrhythmic potential associated with a variety of left ventricular myocardial signal intensities evident on contrast-enhanced cardiovascular magnetic resonance with late gadolinium enhancement (LGE) is unresolved.
Methods and results: In 145 HCM patients (43±15 years old), visually identified areas of LGE in left ventricle were analyzed quantitatively for intermediate (≥4 but <6 SD) and high (≥6 SD above the mean signal intensity of normal myocardium) LGE signal intensity (LGE-SI). Ambulatory Holter ECGs were obtained within 7.8±8.3 weeks of cardiovascular magnetic resonance. HCM patients with nonsustained ventricular tachycardia, ventricular couplets, and premature ventricular contractions showed greater amounts of intermediate LGE-SI (17±7 versus 10±10 g, 16±10 versus 10±11 g, and 13±8 versus 10±13 g, respectively; P=0.003 to <0.001) and greater amounts of high LGE-SI (15±6 versus 10±8 g, 14±9 versus 10±12 g, and 12±7 versus 10±8 g, respectively; P=0.02-0.003) than patients without these arrhythmias. In HCM patients with either nonsustained ventricular tachycardia, couplets, or premature ventricular contractions, the extent of intermediate LGE-SI exceeded that of high LGE-SI (17±7 versus 15±6 g, 16±10 versus 14±9 g, and 13±8 versus 12±7 g, respectively; P=0.01-0.04). In addition, the receiver operating characteristic area under the curve established intermediate LGE-SI as a better discriminator of patients with nonsustained ventricular tachycardia than was high LGE-SI, with 7 additional patients with this arrhythmia identified.
Conclusions: In patients with HCM, intermediate LGE-SI is a better predictor of ventricular tachyarrhythmias (including nonsustained ventricular tachycardia, a risk factor for sudden death) than is high LGE-SI. Longitudinal studies in larger HCM cohorts are justified to define the independent prognostic impact of intermediate LGE-SI.