A high degree of non-compacted (trabeculated) myocardium in relationship to compact myocardium (T/M ratio >2.3) has been associated with a diagnosis of left ventricular non-compaction (LVNC). The Multi-Ethnic Study of Atherosclerosis (MESA) is a population-based longitudinal study initiated in July 2000; with 6814 participants (45-84 years, 3601 women) free of recognized cardiovascular disease at enrollment. The purpose of this study was to determine the normal range of the T/M ratio in MESA and to examine the relationship to demographic and clinical parameters.
The thickness of trabeculation and the compact myocardium were measured in eight regions of the left ventricle on long axis cardiac magnetic resonance (CMR) steady-state free precession cine images in 1000 randomly chosen participants of the “MESA 5” follow-up cohort (551 women; 68.1±8.9 years) and T/M ratios were calculated.
In a subset of 323 participants free of cardiac disease and without known LVNC, 140 (43%) had a T/M ratio >2.3 in at least one region (Figure 1) while 20/323 (6.2%) participants had a T/M ratio >2.3 in more than two regions (Figure 2). 62/323 (19%) had a T/M ratio >2.9 in one region. Multivariate linear regression model revealed no association of age, height and weight with the maximum T/M ratio and trabecluation thickness in participants free of cardiac disease (p>0.05). Maximum trabeculation thickness was associated with Chinese and African American ethnicities and male gender (p<0.05; β=1.5mm, 1.3mm and 1.1mm, respectively). In participants free of cardiac disease, maximum trabeculation thickness and T/M ratio were associated with LV end-diastolic volume (p<0.0001; β=0.03mm/ml and β=0.01/ml, respectively) and end-systolic volume (p<0.001; β=0.06mm/ml and β=0.03/ml, respectively) in adjusted models. Further, there was a negative association of LV ejection fraction with maximum T/M ratio (p=0.044; β=-0.02/%). There was no association of maximum T/M ratio with hypertension or myocardial infarction (p>0.05) in adjusted models of the entire cohort (n=1000). Values for T/M ratio depend on measurement technique: At the apical level median T/M ratios derived from measurements of short axis images were significantly less than the values obtained on long axis images (p=0.017).
Figure 1. Percent subjects with a T/M ratio >2.3 per region at the mid-cavity level (outer circle) and the apical level (inner circle) of the entire cohort (A) and the subset of subjects free of cardiac disease (B).
Figure 2. Percent of subjects of the entire cohort (grey bars) and the subset of subjects free of cardiac disease (black bars) with a T/M ratio >2.3 in 0 to 8 regions per subject. T/M ratio = thickness of trabeculation / thickness of compact myocardium.
Results of the current study suggest a reevaluation of the current CMR criteria for LVNC using a higher cut-off for T/M ratio and including the number of affected regions. A uniform definition of measurement technique is necessary.
This research was supported by contracts N01-HC-95159 through N01-HC-95169 from the National Heart, Lung, and Blood Institute.