Abstract 15881: Delayed Enhancement in Hypertrophic Cardiomyopathy Is Related to Perfusion Abnormalities: An Ischemia-Fibrosis Connection
Hypertrophic cardiomyopathy (HCM) is associated with patchy fibrosis seen by histology and by delayed enhancement (DE) using gadolinium-enhanced magnetic resonance (CMR). The etiology of fibrosis remains unclear. The aim of our study was to examine whether there is a relationship between fibrosis and microvascular ischemia.
Methods/Results: Symptomatic HCM patients (n=22) without obstructive coronary anatomy underwent CMR for assessment of DE. Presence of DE was defined as a signal 6 standard deviations above mean signal intensity for normal remote myocardium. All patients also had 13N-ammonia positron emission tomography (PET) to quantify myocardial blood flow (MBF) and myocardial flow reserve (MFR), and determine a summed difference score(SDS), left ventricular ejection fraction (LVEF) and transient ischemic dilatation (TID) index. Patients with no DE (n=7) were compared to patients with DE (n=15). Clinical and PET characteristics were similar in both groups: age (52±17 vs. 53±16yrs; P=0.9), heart rate (59±4 vs. 62±11bpm;P=0.6), mean blood pressure (91±9 vs. 87±10mmHg; P=0.3), rest LVEF (56±6 vs. 58±7%; P=0.6), and resting MBF (0.85±0.13 vs. 0.93±0.22 ml/min/g; P=0.4). Wall thickness was significantly larger in HCM in the DE group (2.2±0.3 vs1.6±0.1 cm,respectively, p=0.001). After vasodilator stress, peak MBF (2.14±0.35 vs.1.73±0.39 ml/min/g; P=0.03), MFR (2.55±0.29 vs. 1.90±0.48; P=0.004) and LVEF (57± 13 vs. 47±8%;P=0.03) were significantly lower, and SDS (0.4±1.1 vs. 8.5±5.0, P< 0.0001) and TID index (1.0±0.13 vs. 1.16 ± 0.10; P=0.006) significantly higher in patients with than without DE.
Conclusions: Presence of DE in HCM is associated with myocardial perfusion abnormalities and depressed MFR by PET in the setting of non-obstructive epicardial coronary arteries indicating microvascular disease. Our data suggest that microvascular ischemia is a contributor to fibrosis in HCM.
- Imaging agents
- Coronary microcirculation
- Magnetic resonance imaging
- Positron emission tomography
- © 2011 by American Heart Association, Inc.