In hypertrophic cardiomyopathy (HCM), the clinical significance attributable to the
broad range of left ventricular (LV) systolic function, assessed as the ejection fraction
(EF), is incompletely resolved. We evaluated the EF using cardiovascular magnetic
resonance (CMR) imaging in a large cohort of patients with HCM with respect to the
clinical status and evidence of left ventricular remodeling with late gadolinium enhancement
(LGE). CMR imaging was performed in 310 consecutive patients, aged 42 +/- 17 years.
The EF in patients with HCM was 71 +/- 10% (range 28% to 89%), exceeding that of 606
healthy controls without cardiovascular disease (66 +/- 5%, p <0.001). LGE reflecting
LV remodeling showed an independent, inverse relation to the EF (B-0.69, 95% confidence
interval -0.86 to -0.52; p <0.001) and was greatest in patients with an EF <50%, in
whom it constituted a median value of 29% of the LV volume (interquartile range 16%
to 40%). However, the substantial subgroup with low-normal EF values of 50% to 65%
(n = 45; 15% of the whole cohort), who were mostly asymptomatic or mildly symptomatic
(37 or 82% with New York Heart Association functional class I to II), showed substantial
LGE (median 5% of LV volume, interquartile range 2% to 10%). This overlapped with
the subgroup with systolic dysfunction and significantly exceeded that of patients
with an EF of 66% to 75% and >75% (median 2% of the LV volume, interquartile range
1.5% to 4%; p <0.01). In conclusion, in a large cohort of patients with HCM, a subset
of patients with low-normal EF values (50% to 65%) was identified by contrast-enhanced
CMR imaging as having substantial degrees of LGE, suggesting a transition phase, potentially
heralding advanced LV remodeling and systolic dysfunction, with implications for clinical
surveillance and management.
Copyright (c) 2010. Published by Elsevier Inc.