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Left ventricular noncompaction is a congenital cardiomyopathy, which is often first diagnosed in adults. The condition can be found in isolation, but it has also been described in association with other cardiac anomalies. We report here the 4th documented case of left ventricular noncompaction associated with a bicuspid aortic valve and the 1st of these cases in which the patient underwent aortic valve surgery.
Isolated noncompaction of the ventricular myocardium is a rare disorder, with an incidence of 0.05% in the adult population.1 It is recognized that there are associations with other congenital cardiac malformations, including bicuspid aortic valve.2 An excessively prominent trabecular meshwork and deep trabecular recesses characterize myocardial noncompaction, which is caused by the arrest of compaction of myocardial fibers during embryogenesis.3 The echocardiographic criteria for noncompaction have been well described and include, for example, evidence of a 2-layer structure: a thick, noncompacted layer and a thin, compacted layer, displaying a maximal noncompacted-to-compacted thickness ratio of greater than 2.3
Previous studies of noncompaction cardiomyopathy in adults have reported a poor prognosis, with high death and morbidity rates from heart failure, thromboembolic events, and ventricular arrhythmias.4 One study found that 48% of patients died or underwent cardiac transplantation during a mean follow-up period of 44 months. A more recent study, however, has suggested a more favorable prognosis: only 1 death among 45 patients studied during a mean follow-up period of 46 months.5 Notably, patients with impaired systolic function in this study experienced improvement in New York Heart Association (NYHA) functional class symptoms with medical treatment, and the cohort of patients with normal systolic function had no death or progression to heart failure. One of the reasons for this apparent discrepancy in findings is that the latter study appeared to enroll patients who had a milder phenotype or were in the asymptomatic phase of the disease. An even more recent study indicates a wider spectrum of disease progression, from a more severe prognosis (in association with elevated NYHA functional class at 1st observation and with a history of sustained ventricular tachycardia) to a more stable course (in association with an incidental finding of noncompaction).6
In February 2007, a 39-year-old man, apparently fit and well, presented with a 6-month history of intermittent palpitations. These episodes lasted several seconds and did not result in dizziness or loss of consciousness. He was otherwise asymptomatic and, in particular, had never experienced exertional chest pain or breathlessness. He consumed little alcohol and was a nonsmoker. The physical examination was unremarkable except for a diastolic murmur at the left sternal edge. Twelve-lead electrocardiography (ECG) showed sinus rhythm with a left axis, ventricular ectopic beats, and voltage criteria indicative of left ventricular hypertrophy. The patient underwent 24-hour ambulatory ECG recording, which revealed frequent ventricular extrasystoles and several short salvos of nonsustained ventricular tachycardia, although he was asymptomatic during the recording. Routine transthoracic echocardiography revealed prominent trabeculations and deep intertrabecular recesses in the left ventricle, which involved the apex and the lateral wall. The recesses were supplied by intraventricular blood as demonstrated upon color-flow Doppler echocardiography. A bicuspid aortic valve was also seen, in association with moderate aortic regurgitation that was manifest via pressure half-time measurement and color-flow Doppler. The patient's left ventricle was dilated (end-diastolic dimension, 6.1 cm), but his systolic function was good. The left ventricular trabeculations were seen particularly well on subsequent transesophageal echocardiography (Fig. 1). He also underwent cardiac magnetic resonance imaging, which once again confirmed the diagnosis of left ventricular noncompaction (Fig. 2).
There was a concern that the patient might develop left ventricular systolic dysfunction and overt heart failure due to the combination of moderate aortic regurgitation and noncompaction, despite his demonstrating good left ventricular systolic function at the time of diagnosis. A repeat echocardiogram performed 4 months later showed very slight progression of the aortic regurgitation but no change in left ventricular dilation and systolic function. After establishing the patient on conventional heart-failure medications, including an angiotensin-converting enzyme inhibitor and a β-blocker, we chose to schedule him for aortic valve replacement despite his continuing lack of symptoms and preserved left ventricular systolic function. This uneventful surgical procedure was performed with a standard Sorin Bicarbon mechanical prosthesis (Sorin Biomedica Cardio; Saluggia, Italy). Our patient made a good recovery and reported that his palpitations had reduced in frequency. This was confirmed by repeat (postoperative) 24-hour Holter monitoring, which revealed that his ventricular ectopic beats had decreased from 944 in 24 hours (seen on the 1st tape) to fewer than 100 in 24 hours. The repeat 24-hour tape also did not show any nonsustained ventricular tachycardia. A repeat transthoracic echocardiogram 4 months after surgery showed that the left ventricular dilation had not progressed and that systolic function was preserved.
Recent data have suggested that patients who are diagnosed with left ventricular noncompaction in the asymptomatic period tend to have significantly better outcomes than do patients who have symptoms of heart failure or a history of sustained ventricular tachycardia.6 Although our patient presented while asymptomatic, we felt that the combination of moderate aortic regurgitation and noncompaction would render his prognosis less favorable. Indeed a similar case has been described in which a patient with noncompaction and moderate aortic regurgitation from a bicuspid valve suffered rapid deterioration and subsequent death.2 The degree of left ventricular dilation in our patient was surprising, given that the aortic regurgitation was moderate; we might surmise that left ventricular dilation was accelerated by the associated volume overload. The development of overt heart failure may have been the next stage, had we had not intervened. It was most encouraging to see that in the 4-month period after valve replacement, left ventricular systolic function was preserved—in the absence of further left ventricular dilation and further ventricular arrhythmias.
To the best of our knowledge, this is only the 4th documented case2,7 of left ventricular noncompaction associated with a bicuspid aortic valve and the 1st reported case in which a patient with noncompaction underwent replacement of a bicuspid aortic valve. Coexisting congenital valvular abnormalities have been documented in cases of noncompaction, and this case report reinforces our awareness of the need to identify and treat these abnormalities, particularly if they contribute to a decline in the patient's condition.
Address for reprints: Benjamin J. Wrigley, MBChB, MRCP, Department of Cardiology, University Hospital, Clifford Bridge Road, Coventry CV2 2DX, England, UK. E-mail: moc.liamtoh@yelgirwneb