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Left ventricular noncompaction (LVNC) is characterized by the presence of an extensive trabeculated layer of myocardium adjacent to normal compacted myocardium of the left ventricle. Mutations of the cardiac sarcomere have been identified as causing LVNC and are also the genetic basis for the majority of hypertrophic cardiomyopathy (HCM) mutations. However, whether phenotypic overlap exists between LVNC and HCM is uncertain. Therefore, we sought to determine the prevalence of diagnostic criteria for LVNC among a cohort of HCM patients.
Cardiovascular magnetic resonance (CMR) was performed on 43 consecutive HCM patients (47 ± 15 years old; 71% male) without a previous diagnosis of LVNC. In a total of 10 left ventricular (LV) myocardial segments, the area of maximal trabeculated myocardium and compacted myocardium were measured and expressed as a ratio (T/C ratio) in each of 4 apical short-axis segments and the 6 segments of the mid-LV slice, with care taken to exclude papillary muscles. A T/C ratio ≥2.3:1 defined LVNC.
Among 43 HCM patients, maximal LV wall thickness was 20 ± 5 mm, rest LV outflow tract obstruction present in 8 patients (19%), and 21 patients (49%) were genotyped and identified as having a pathogenic sarcomere protein mutation, the two most common being MYH7 and MYBPC3 (85%). A T/C ratio of ≥2.3:1 was present in ≥1 LV myocardial segment in 30 of the 43 HCM patients (70%), in ≥2 LV segments in 19 patients (44%) and in ≥ 3 LV segments in 11 patients (26%). Of the 72 wall segments that met criteria for a T/C ratio ≥ 2.3, 48 (67%) were apical segments and 24 (33%) were mid-LV segments. The average T/C ratio was 3.3:1 among segments that met diagnostic criteria. A T/C ratio of ≥2.3:1 was present with similar prevalence in HCM patients with or without an identified sarcomere mutation (71 % vs 75 %; p=0.82). If a stricter T/C ratio of ≥3.0 was considered, 18 patients (42%) would still meet criteria.
In this CMR-based study, the majority of HCM patients meet the current diagnostic imaging criteria for LVNC. These observations suggest that noncompacted areas of myocardium are not an uncommon part of the phenotypic expression of HCM.
Moderated Poster Contributions
Poster Sessions, Expo North
Monday, March 11, 2013, 9:45 a.m.-10:30 a.m.
Session Title: What to Look for When Evaluating Hypertrophic Cardiomyopathy
Abstract Category: 23. Pericardial/Myocardial Disease
Presentation Number: 1295M-155
- 2013 American College of Cardiology Foundation