Impairment of myocardial perfusion correlates with heart failure severity in patients with non-compaction cardiomyopathy

Myocardial Mechanics and Associated Valvular and Vascular Abnormalities in Left Ventricular Noncompaction Cardiomyopathy

Left ventricular (LV) non-compaction (LVNC) is a rare genetic cardiomyopathy due to abnormal intra-uterine arrest of compaction of the myocardial fibers during endomyocardial embryogenesis. Due to the partial or complete absence of LV compaction, the structure of the LV wall shows characteristic abnormalities, including a thin compacted epicardium and a thick non-compacted endocardium with prominent trabeculations and deep intertrabecular recesses. LVNC is frequently associated with chronic heart failure, life-threatening ventricular arrhythmias, and systemic embolic events. According to recent findings, in the presence of LVNC, dysfunctional LV proved to be associated with left atrial volumetric and functional abnormalities and consequential dilated and functionally impaired mitral annulus, partly explaining the higher prevalence of regurgitation. Although the non-compaction process morphologically affects only the LV, signs of remodeling of the right heart were also detected. Moreover, dilation and stiffening of the aorta were present. The aim of the present detailed review was to summarize findings regarding changes in cardiac mechanics, valvular abnormalities, and vascular remodeling detected in patients with LVNC.

Myocardial perfusion in excessively trabeculated hearts: Insights from imaging and histological studies

In gestation, the coronary circulation develops initially in the compact layer and it expands only in fetal development to the trabeculations. Conflicting data have been published as to whether the trabecular layer is hypoperfused relative to the compact wall after birth. If so, this could explain the poor pump function in patients with left ventricular excessive trabeculation, or so-called noncompaction. Here, we review direct and indirect assessments of myocardial perfusion in normal and excessively trabeculated hearts by in vivo imaging by magnetic resonance imaging (MRI), positron emission tomography (PET)/single photon emission computed tomography (SPECT), and echocardiography in addition to histology, injections of labelled microspheres in animals, and electrocardiography. In MRI, PET/SPECT, and echocardiography, flow of blood or myocardial uptake of blood-borne tracer molecules are measured. The imaged trabecular layer comprises trabeculations and blood-filled intertrabecular spaces whereas the compact layer comprises tissue only, and spatio-temporal resolution likely affects measurements of myocardial perfusion differently in the two layers. Overall, studies measuring myocardial uptake of tracers (PET/SPECT) suggest trabecular hypoperfusion. Studies measuring the quantity of blood (echocardiography and MRI) suggest trabecular hyperperfusion. These conflicting results are reconciled if the low uptake from intertrabecular spaces in PET/SPECT and the high signal from intertrabecular spaces in MRI and echocardiography are considered opposite biases. Histology on human hearts reveal a similar capillary density of trabecular and compact myocardium. Injections of labelled microspheres in animals reveal a similar perfusion of trabecular and compact myocardium. In conclusion, trabecular and compact muscle are likely equally perfused in normal hearts and most cases of excessive trabeculation.

NT-pro-BNP in patients with left ventricular hypertrabeculation/non-compaction

Aims

Left ventricular hypertrabeculation/non‐compaction (LVHT) is a cardiac abnormality of unknown pathogenesis and frequently associated with neuromuscular disorders. The N‐terminal fragment of the pro brain natriuretic peptide (NT‐pro‐BNP) is a prognostic marker in heart failure whose relevance in LVHT patients is largely unknown. The aim of the study was to assess the role of NT‐pro‐BNP levels as prognostic markers in LVHT.

Methods and results

Data of LVHT patients were collected in a database from one echocardiographic laboratory since 1996. The hospital information system was screened for measurements of NT‐pro‐BNP levels, and their association with clinical and echocardiographic baseline parameters was retrospectively assessed. During follow‐up, the endpoints were death and heart transplantation. In 113 patients (median age 57 years, 24% women), data about NT‐pro‐BNP measurements were found, ranging from 8 to 121 152 (median 2029) ng/L. High NT‐pro‐BNP levels were associated with heart failure, valvular abnormalities, diabetes mellitus, hypertension, angina pectoris, number of LVHT‐affected segments, end‐diastolic diameter, and systolic dysfunction. During a follow‐up of 73 (±64; 0–237) months, 35% of the patients reached an endpoint. High NT‐pro‐BNP levels were associated with the occurrence of an endpoint (P < 0.001). By multivariate analysis, predictors for endpoints were increased age (P = 0.0025), atrial fibrillation (P = 0.0023), natural logarithm of NT‐pro‐BNP levels (P = 0.0073), diabetes mellitus (P = 0.014), and thromboembolic events before diagnosis (P = 0.0347).

Conclusions

Also in LVHT patients, high NT‐pro‐BNP levels are indicators for death and heart transplantation.

Impairment of myocardial perfusion correlates with heart failure severity in patients with non-compaction cardiomyopathy

Aims

Non‐compaction cardiomyopathy (NCM) is a congenital heart disease characterized by an arrest of the myocardial compaction process. Although NCM patients have impaired formation of microvasculature, the functional impact of these changes remains undefined. We sought to analyse a potential correlation between myocardial ischemia and heart failure severity in NCM patients.

Methods and results

We enrolled 41 NCM patients (28 male and 13 female), aged 21–70 years. In all patients, we have determined left ventricular end‐diastolic volume (LVEDV), left ventricular ejection fraction (LVEF), and global longitudinal strain (GLS) by echocardiography. At the same time, serum levels of N‐terminal pro‐B‐type natriuretic peptide (NT‐proBNP) have been measured, and myocardial single‐photon emission computed tomography at rest and on stress was used to define significant myocardial ischemia defined as summed difference score ≥ 2. Myocardial ischemia has been demonstrated in 11 patients (27%, Group A), and 30 patients showed no significant ischemic changes (73%, Group B). The groups did not differ in sex, age, kidney, or liver function. When compared with Group B, Group A had significantly lower LVEF (35 ± 15% in Group A vs. 53 ± 11% in Group B, P < 0.001), higher LVEDV (188 ± 52 mL vs. 136 ± 52 mL, P = 0.007), lower GLS (−9.9 ± 5.2% vs. −14.5 ± 4.1%, P = 0.001), and higher NT‐proBNP levels (1691 ± 1883 pg/mL vs. 422 ± 877 pg/mL, P = 0.006). Overall, higher summed difference score was associated with lower LVEF (r = −0.48, P = 0.001), higher LVEDV (r = 0.39, P = 0.012), lower GLS (r = 0.352, P = 0.024), and higher levels of NT‐proBNP (r = 0.66, P < 0.001).

Conclusions

The presence of myocardial ischemia in patients with NCM is associated with worse left ventricular function, dilation of the left ventricle, and more pronounced neurohumoral activation.