Title:
Prognostic significance of late gadolinium enhancement quantification in cardiac magnetic resonance imaging of hypertrophic cardiomyopathy with systolic dysfunction.

Abstract:
Hypertrophic cardiomyopathy (HCM) with systolic dysfunction carries a poor prognosis. Although late gadolinium enhancement (LGE) on cardiac magnetic resonance is associated with adverse cardiac events in HCM and is inversely related to left ventricular ejection fraction (LVEF), it is unknown whether LGE or LVEF more accurately predicts adverse cardiac events in HCM with systolic dysfunction. We retrospectively assessed the extent of LGE with a threshold of 6 standard deviations in 46 consecutive HCM patients with systolic dysfunction defined as LVEF <50 % (average 35 ± 12 %) who underwent cardiac magnetic resonance (35 males, mean age 59 ± 14 years). They were followed up over 1755 ± 594 days. The composite adverse cardiac events end point included cardiovascular death, lethal arrhythmia, cardioembolic stroke, and unplanned heart failure hospitalization. LGE was detected in all patients, and the mean extent was 30 ± 15 %. Twenty-nine patients developed adverse cardiac events. Multivariate Cox proportional hazard analysis revealed the extent of LGE as a good independent predictor of adverse cardiac events. Risk increased with the extent of LGE (hazard ratio = 1.62/10 % increase in LGE, 95 % confidence interval = 1.23-2.15, p < 0.001). LVEF was inversely related to the extent of LGE (r = -0.44; p = 0.002) and was also an independent predictor of adverse cardiac events. Risk decreased with LVEF (hazard ratio = 0.68/10 % increase in LVEF, 95 % confidence interval = 0.51-0.91, p = 0.010). The Akaike information criterion evaluating the fit of a model demonstrated that the extent of LGE was a better independent predictor of MACE than LVEF (Akaike information criterion = 172.20 and 178.09, respectively).The extent of LGE was a good independent predictor of adverse cardiac events and reflected mortality and morbidity more precisely than LVEF in HCM with systolic dysfunction.