Isolated ventricular noncompaction is associated with coronary microcirculatory dysfunction

Objectives We sought to analyze whether a microcirculatory dysfunction might be associated with isolated ventricular noncompaction (IVNC). Background In IVNC, which is a cardiomyopathy thus far “unclassified” by the World Health Organization, heart failure and sudden cardiac death are common findings, but the pathophysiologic mechanisms are unknown. Methods In 12 patients with IVNC and 14 control subjects, quantitative evaluation of regional myocardial perfusion (myocardial blood flow [MBF]) and coronary flow reserve (CFR, hyperemic/baseline MBF) was performed using positron emission tomography and 13N-ammonia. The left ventricular myocardium was divided into nine segments, and the two-dimensional echocardiogram in each patient with IVNC was compared with CFR in each segment. Noncompaction was defined as a two-layered structure with excessive trabeculation. Results The CFR in control subjects averaged 4.2 ± 0.9, providing a cut-off value ≥2.5, but it was 2.1 ± 0.8 in patients with IVNC. A perfusion scan defect was found in 14 of 24 segments with noncompaction, although no defect was found in 76 of 84 normal segments (overall agreement 83%, p < 0.0001 by the chi-square test). In 16 of 21 segments with noncompaction, a decreased CFR was found; but a decreased CFR was also found in 36 of 60 segments without noncompaction (p = NS). In 45 of the 57 segments with wall motion abnormalities, CFR was decreased, but it was preserved in 17 of the 24 segments with normal wall motion (agreement 77%, p < 0.0001). Conclusions In patients with IVNC, a decreased CFR is not confined to noncompacted segments, but extends to most segments with wall motion abnormalities. Thus, coronary microcirculatory dysfunction is associated with IVNC.