Is Left Ventricular Noncompaction Only a Morphological Feature? A Case of Disappearance of Noncompaction after Surgical Correction of Aorto-Right Ventricular Fistula, Interventricular Septal Defect and Aortic Stenosis.

A 55-year-old man complaining of worsening dyspnea on exertion was diagnosed with restrictive interventricular septal defect, left ventricular noncompaction (LVNC), mild aortic valve stenosis and aorto-right ventricular fistula. He underwent surgical aortic valve replacement with a mechanical bileaflet valve (St. Jude n. 23) and contextual direct suture of interventricular septal defect and closure of aorto-right ventricular fistula. At 2 years of follow-up, the patient was in good general condition. A complete echocardiographic examination showed normalization of left ventricular dimensions and ejection fraction. Furthermore, left ventricular trabeculations became less evident and no longer met the diagnostic criteria for noncompaction. In our case, the expected left ventricular reverse remodeling after cardiac surgery was associated with a significant reduction in LVNC features. In conclusion, physicians should be careful in avoiding overdiagnosis of LVNC, whose features may indeed reflect only the hypertrabeculated morphology of a normal or pathological heart.

CASE REPORT

A 55-year-old man complaining of worsening dyspnea on exertion over the last 15 days was admitted to our Cardiology Division (NYHA functional class III). The patient was previously diagnosed with restrictive interventricular septal defect at age 25 and one episode of ectopic atrial arrhythmia 3 years before. Chest auscultation revealed a wide split S2, a grade 4/6 holosystolic ejection murmur in the second right intercostal space, and fine rales in the mid and lower zones of both lung fields. On clinical evaluation, mild peri-tibial edema was found. The electrocardiogram recorded sinus rhythm with first-degree atrio-ventricular block (PR 240 msec) and left anterior fascicular block. Therapy with diuretics, vasodilators, Angiotensin-converting enzyme inhibitors and then carvedilol resulted in hemodynamic stabilization. Complete echocardiographic examination showed [Figure 1] an enlarged left ventricular (LV) end-diastolic diameter (63 mm), a reduced ejection fraction (EF) according to the Simpson's method (EF = 30%), and a two-layer structure with a compacted, thin epicardial band and a much thicker noncompacted endocardial layer of trabecular meshwork with deep endomyocardial spaces. The predominant localization of the hypertrabeculation was observed in the posterior and antero-lateral areas [Figure 2]. Echocardiographic imaging met the diagnostic criteria for left ventricular noncompaction (LVNC) proposed by Jenny: The end systolic noncompacted/compacted layer ratio was 2.3, Color Doppler evidenced deeply perfused intertrabecular recesses.[1] A restrictive perimembranous interventricular septal defect was confirmed. Mild aortic stenosis (max gradient 28 mmHg) of a sclerocalcific aortic valve was evidenced. Echocardiography also revealed a systo-diastolic flow with aliasing within the supravalvular aortic region with a major diastolic component (diastolic gradient 80 mmHg, systolic gradient 45 mmHg) Blood flow was unidirectional [Figure 3] from the aorta to the right heart chamber, as occurs in high-output aorto-right ventricular fistula.[2] Moderate mitral regurgitation and mild tricuspid regurgitation were also evidenced. Cardiac magnetic resonance (CMR) confirmed LVNC: Increased intraventricular trabeculations of the lateral and posterior wall were evidenced, as well as a thin trabecula network with a two-layer wall structure in the mid and distal ventricular cavity [Figure 4]. The reasons of LV hypertrabeculation and it of its regression will be discussed later in the text. Angiography confirmed the presence of an aorto-right ventricular fistula and the absence of significant coronary lesions. Right heart catheterization showed significant left-to-right shunt. Twenty-four hour ambulatory ECG recorded frequent premature ventricular contractions and runs of nonsustained ventricular tachycardia (NSVT). The electrophysiological study showed normal sinus and atrio-ventricular node conduction. Supraventricular arrhythmias were not inducible at baseline or during isoproterenol infusion. Triple extrastimuli were delivered from the right ventricular apex, and a fast ventricular tachycardia (VT) was induced and cardioverted with DC-shock. An electroanatomic map of the left ventricle was created using the CARTO system. The voltage map did not show any abnormalities consistent with scarred tissue. No fractionated electrogram, double potential or distinct Purkinjie potential was recorded. The presence of the fistula between the aortic root and the right ventricle was confirmed.

Figure 1

M-mode echocardiogram before surgery, showing severe dilatation of left ventricular dilatation and hypokinesia of the regional wall motion

Figure 2

Echocardiographic apical long-axis view before surgery, showing noncompacted myocardial layers in the mid-apical portion of the posterior wall, with prominent trabeculae and deep intertrabecular recesses

Figure 3

Color Doppler in apical off-axis view before surgery, showing systo-diastolic supravalvular aortic flow directed towards the right ventricle, referred to as aorto-right ventricular fistula

Figure 4

Magnetic resonance image before surgery, showing prominent left ventricular trabeculation with the typical two-layer structure of the myocardial wall, consisting of a thin compacted epicardial layer and a thick non compacted endocardial layer, located in the mid-apical portion of the posterior and apical walls, confirming the diagnosis of left ventricular noncompaction

Due to the history of syncope, the occurrence of spontaneous NSVT and the inducibility of fast VT, a dual chamber implantable cardioverter-defibrillator was implanted. The patient underwent surgical aortic valve replacement with a mechanical bileaflet valve (St. Jude n. 23) and contextual direct suture of interventricular septal defect and closure of aorto-right ventricular fistula. At two years of follow-up, the patient was in good general condition, in NYHA functional class I. Complete echocardiographic examination showed normalization [Figure 5] of LV end-diastolic diameter (54 mm) and EF (62%). Furthermore, LV trabeculations were less prominent and no longer met the diagnostic criteria for noncompaction [Figure 6]. Continuity of the perimembranous interventricular septum was confirmed. A well-functioning bileaflet St. Jude mechanical valve and closure of the aorto-right ventricular fistula were appreciated. This case highlights several issues regarding the diagnosis of LVNC. Different hemodynamic mechanisms may account for EF reduction and LV dilatation in this patient, including widespread hypokinesia secondary to LVNC, the presence of aorto-right ventricular fistula and aortic stenosis. Disappearance of hypertrabeculation in dilated cardiomyopathy patients after LV geometry improvement has already been reported.[3] Furthermore, it has recently been reported on CMR that the global amount of trabeculation is positively correlated with LV sphericity index, suggesting that “concealed” trabeculations can became manifest when LV modifies its geometry and increases its sphericity and, on the opposite, become less evident when LV undergoes a favorable reverse remodeling.[4] We hypothesize that also in our patient, post surgical left ventricular reverse remodeling could explain the regression of noncompaction morphology.

Figure 5

M-mode echocardiogram after surgery, showing normalization of left ventricular dimensions and regional wall motion

Figure 6

Echocardiographic apical off-axis view after surgery, showing reduced noncompacted myocardial layers in the mid-apical portion of the inferior-posterior and antero-lateral walls and normalization of left ventricular volume

CONCLUSIONS

Physicians should be careful in avoiding overdiagnosis of LVNC, whose features may indeed reflect only the hypertrabeculated morphology of a normal or pathological heart.[567]