In this article, we describe three cases of heart failure that did not fit the general categories of cardiomyopathy (CM), namely dilated, hypertrophic, non-dilated, non-hypertrophic types. The salient feature was non-compaction of the left ventricular (LV) myocardium on 2D echocardiography (2DE).
The normal LV myocardium is compact with scarce, inconspicuous, or no trabeculation. Trabeculae are muscular bands of the endocardium separated by spaces. The intertrabecular spaces are normally shallow or not prominent.
Non-compaction cardiomyopathy (NCCM) is characterized by prominent, protruding trabeculae and deep intertrabecular spaces caused by a failure of the myocardium to compress into a solid form. Previously considered rare, NCCM is receiving increasing attention as a result of an increase in the awareness of this condition.
Case Reports
Case 1
A 49-year-old man with a non-specific history of ‘heart trouble’ presented with a clinical picture of biventricular failure: exertional dyspnea, sinus tachycardia, a few bibasal crepitations, and mild pitting edema of the ankles. The chest radiogram showed an enlarged cardiac shadow and a small right pleural effusion. The 2DE showed LV hypertrophy (LVH) and generalized hypokinesis. The LV ejection fraction (LVEF) was 0.25. The right atrium and the right ventricle were marginally dilated. The most impressive echocardiographic feature was the presence of extensive and prominent trabeculae that protruded into the LV cavity. Between the trabeculae were deep, penetrating intertrabecular recesses affecting the apex and mid-lateral wall. These recesses opened to the LV cavity (see Figure 1).
Case 2
A 67-year-old man with gradually deteriorating physical capacity was hospitalized with marked respiratory distress and palpitations. His initial blood pressure was 160/100mmHg, which normalized with treatment and remained normal throughout hospitalization. There was tachycardia and S4 gallop. An apical holosystolic murmur was present. Bilateral pulmonary rales were present. The jugular veins were distended.
There was significant enlargement of the cardiac shadow and pulmonary venous dilatation seen on chest radiogram. Edema of the ankles was present. A diagnosis of hypertensive heart disease with biventricular failure was made. The 2DE revealed four-chamber dilatation, mild LVH, and diffuse hypokinesis of the ventricles. The LVEF was 0.35. The apex and anterolateral walls (see Figures 2 and 3) revealed non-compaction, that is projecting trabeculae with intervening deep interspaces, some of which appeared to extend through most of the thickness of the LV wall. The bases of the papillary muscles were also affected. The Doppler revealed severe mitral regurgitation and color flow in and out of the interspaces. The Doppler findings were also consistent with mild tricuspid regurgitation and a derived right ventricular (RV) systolic pressure of 50mmHg.
Case 3
A 51-year-old woman who had been treated intermittently for asthma during the previous year was hospitalized with features of LV failure: dyspnea, tachycardia, tachypnea, and basal crepitations. There was no wheezing. The initial blood pressure was 150/90mmHg, which subsequently normalized. The 2DE demonstrated LVH, LV hypokinesis, and an LVEF of 0.40. Multiple prominent trabeculae and deep penetrating intertrabecular recesses (similar to those described above) were present (see Figure 4). The color flow Doppler revealed flow into some of the recesses.
Discussion
NCCM is characterized by protruding trabeculations of the myocardium with interlaying deep, penetrating spaces. The main affected area is the apex, but sometimes other segments are affected. Current opinion is that the fetal myocardium derives its blood supply directly from the LV cavity. Protruding trabeculae afford a large surface area that facilitates oxygenation. As the circulation changes to the epicardial coronary system, the trabeculae disappear by a process of compaction. If this process is incomplete, regions of the LV wall may remain non-compacted.1
Engberding et al. have suggested four echocardiographic criteria: presence of at least four prominent trabeculations; involvement of the apex and inferior and mid-lateral wall segments; appearance of blood flow from the LV cavity into the recesses shown by color Doppler examination; and absence of co-existing diseases.1 Our patients met the first three criteria. In terms of the last criterion, none had other etiologies including chronic or severe hypertension or coronary disease (angina, regional wall motion abnormalities, or electrocardiographic abnormalities). Nuclear stress imaging in case 2 and coronary angiography in case 3 were normal.
The major presentation of NCCM is heart failure. Others include ventricular arrhythmias and embolization from thrombus formed inside the intertrabecular recesses.2–4 2DE findings are LV dysfunction, LVH, and mitral regurgitation. We hypothesize that non-compaction and the resulting loss of functional myocardium lead to LV failure and compensatory LVH. LV dysfunction may deteriorate with mitral regurgitation from papillary muscle involvement. Echocardiography and Doppler examination are usually sufficient for the diagnosis of NCCM. In doubtful cases, magnetic resonance imaging may be helpful.5