Abstract 17403: Extent of Late Gadolinium Enhancement in Cardiac Magnetic Resonance and Its Relationship with Left Ventricular Longitudinal Functional Reserve During Exercise in Patients with Hypertrophic Cardiomyopathy
Background: Late gadolinium enhancement (LGE) is a common abnormal observation in gadolinium-enhanced cardiac magnetic resonance (CMR) in hypertrophic cardiomyopathy (HCM), which reflects myocardial fibrosis. We hypothesized that the extent of LGE would correlate with parameters of LV functional reserve during exercise in HCM patients.
Methods: Mitral septal annular systolic (S') and early diastolic (E') velocities were measured at rest and during graded supine bicycle exercise (25W, 3-minute increments) in 46 HCM patients (32 male, mean age 53 years). LV longitudinal diastolic and systolic functional reserve indices were calculated as follows; diastolic function reserve index=ΔE'×E'base, where ΔE' is the change in E' from baseline to 50 W of exercise, systolic reserve index=ΔS'×S'base, where ΔS' is the change in S' from baseline to 50 W of exercise. The degree of myocardial fibrosis was assessed with gadolinium-enhanced CMR. The study patients were divided into two groups according to the extent of LGE (% of LGE mass to LV mass [range; 0 to 37%, the median=6%]): Group 1 (n=23) with larger extent of LGE (LV with LGE ≥ 6%) and Group 2 with lesser extent of LGE.
Results: There were no significant differences in resting echocardiographic parameters between two groups except S' (5.0±1.0 vs. 5.8±1.2 cm/s) and deceleration time of mitral inflow (230±75 vs. 190±36 ms) (P<0.05). However, increments of E' and S' during exercise were significantly smaller in Group 1 (ΔE': 1.5±1.0 vs. 2.8±1.8 cm/s; ΔS': 0.9±0.8 vs. 2.2±1.2 cm/s [P<0.05 for all]). In addition, LV functional reserve indices were significantly lower in Group 1 (diastolic index: 5.5±3.4 vs. 12.8±7.7; systolic index: 4.7±4.5 vs. 12.6±7.4 [P<0.05 for all]).
Conclusion: Augmentation of LV longitudinal function during exercise is more blunted in HCM patients with greater extent of LGE on CMR. The extent of myocardial fibrosis might be a pathologic substrate which determines LV functional reserve during exercise in HCM.
- © 2010 by American Heart Association, Inc.