To the Editor:
The following questions and concerns need to be answered to put Punn and Silverman’s findings in perspective.
Concerning the methods, it would be of interest to know in how many patients it was possible to assess all 16 cardiac segments for the presence or absence of left ventricular hypertrabeculation (LVHT) and whether interobserver studies for these measurements were carried out. How were papillary muscles, false tendons, and aberrant bands differentiated from LVHT when performing measurements in short-axis views?
In the results, there is a discrepancy between the assessment of systolic function by left ventricular fractional shortening and left ventricular ejection fraction. Punn and Silverman state that in LVHT, systolic function should be assessed using the ejection fraction, not fractional shortening. In our experience in adults, this is rather impossible, because planimetry is heavily impeded by the trabeculations. More details how these measurements were performed should be provided. How many segments were without any noncompacted layer at all, and was LVHT more pronounced in dilated than in normally sized ventricles? How do the authors explain that the interventricular septum was relatively rarely affected by LVHT, a finding that has been previously reported? In how many patients who died or underwent cardiac transplantation was the heart investigated pathoanatomically or histologically, and how often was LVHT confirmed?
Among adults, it has been observed that LVHT regresses after heart failure therapy when the initially dilated left ventricles decrease in size. Because patients in Punn and Silverman’s study underwent follow-up after a mean of 18 months, information should be provided as to whether the extension and severity of LVHT changed during the disease course.
LVHT is associated with various extracardiac, especially neuromuscular disorders and chromosomal abnormalities. How many of Punn and Silverman’s patients had clinically manifest or subclinical neuromuscular disorders or chromosomal abnormalities, and did their prevalence differ between the two groups?
All these open questions and concerns need to be answered before Punn and Silverman’s findings can be assessed. If LVHT is present irrespective of the ratio value, definitions that use these measurements should be revised and LVHT defined simply as a two-layered myocardial structure with an inner noncompacted and an outer compacted layer.