We read with interest the report entitled “Examination of Isolated Ventricular Noncompaction (Hypertrabeculation) as a Distinct Entity in Adults.” The authors describe the morphologic features of explanted hearts in 3 patients who underwent heart transplantation and reviewed previously published reports illustrating the heart at necropsy or after cardiac transplantation.

We congratulate the authors for the excellent morphologic illustrations of isolated ventricular noncompaction (IVNC). We agree that cuts of the ventricles parallel to the posterior atrioventricular sulcus after fixation or short-axis views provide the best opportunity to demonstrate the 2-layered structure of the myocardial wall consisting of a compacted epicardial layer and a markedly thickened noncompacted endocardial layer. These cuts of the anatomic specimens mirror the short-axis views obtained by transthoracic echocardiography. This inspired the Zurich team to establish echocardiographic diagnostic criteria for IVNC, which were derived from the short-axis view. The Zurich criteria were also validated against other cardiomyopathies.

The exponential increase in publications reflects increasing interest and awareness of this phenotype. We agree with the authors that advances in noninvasive diagnostic technologies enable better delineation of the morphologic appearance of the myocardium, which have increased the detection rate of IVNC. However, echocardiographers and clinicians have to be cautioned not to overdiagnose IVNC because the morphologic spectrum of trabeculations, from normal variants to pathologic trabeculations with the morphologic feature of IVNC, must be carefully considered.

The authors reviewed 18 gross photographs of the heart in adults with IVNC in previously published peer-reviewed journals. According to the opinion of 1 of the authors (W.C. Roberts), only 7 of the 18 cases represent clear examples of IVNC. Dr. Roberts argued that the photograph shown in 1 report appeared to be a classic example of cor pulmonale.

We disagree with this statement. This gross specimen is a trans-sectional view from the anterior of the dorsal 1/2 of the heart in a 21-year-old man who presented in cardiogenic shock. Two different imaging techniques and pathology confirmed IVNC in this poor young man. Left ventricular angiogram obtained 3 weeks before his death confirmed the echocardiographic diagnosis and revealed a severely thickened myocardial wall with prominent trabeculations and deep intertrabecular spaces filled with blood from the left ventricular cavity. Right ventricular angiogram showed the same morphologic appearance consistent with IVNC. Hemodynamic assessment was consistent with restrictive physiology and subsequent increased pulmonary artery pressures. The coronary arteries were normal. Autopsy examination confirmed the echocardiographic and angiographic findings as shown in the photograph.

The gross specimen showed a severely thickened myocardium of the 2 ventricles with prominent trabeculations and deep intertrabecular recesses. There was also marked fibroelastosis of the left ventricle. In contrast to the authors’ assumption, the heart was first fixed in formalin (formalin bath and perfusion of the coronary arteries with formalin) and then opened by cuts according to blood flow. These cuts were chosen to have a gross heart specimen corresponding to the apical 4-chamber view obtained by echocardiography. The right ventricle in this patient was enlarged, more than expected in a patient with IVNC. We agree with Dr. Roberts in that regard: the enlargement of the right ventricle was caused by an advanced form of IVNC and by pulmonary hypertension secondary to systolic and diastolic left ventricular dysfunctions in the presence of impressive IVNC and endocardial fibroelastosis and subsequent restrictive physiology. An increase of pulmonary artery pressure added to right ventricular remodeling and to severe morphologic features of IVNC. The underlying pathology, however, was not a cor pulmonale.

Some of the references were not carefully reviewed. The work by Aras et al included 67 adults with IVNC (57 adult patients plus 10 adult relatives of those index cases) and not 57 cases, as the authors reported on page 747. In addition, there is another misquotation on page 748: “… in 2010, 140 more adults were reported, each study from single medical centres [reference 22].” The work by Aras et al (reference 22 in the article under discussion) was published in 2006 and not 2010; the authors referred to another article.

The term “hypertrabeculation” as used by the authors is not appropriate. Hypertrabeculation implies an increased number of normally formed trabeculations. The histologic appearance of noncompacted myocardium (IVNC), however, is far beyond normal.