Original ArticleIncreasing Identification of Isolated Left Ventricular Non-Compaction with Cardiovascular Magnetic Resonance: A Mini Case Series Highlighting Variable Clinical Presentation
Introduction
Isolated ventricular non-compaction (IVNC) is a rare congenital cardiomyopathy, which currently remains unclassified by the World Health Organization. It was first described in children and is characterised by the presence of a highly trabeculated left ventricular (LV) myocardium with adjacent deep intertrabecular recesses. The intertrabecular recesses are covered with a continuous endocardial lining and are not in communication with the coronary vasculature. The condition is found in the absence of other cardiac anomalies. IVNC is believed to be a genetically inherited disorder caused by the intrauterine arrest of compaction of myocardial fibres during foetal morphogenesis. Clinically IVNC has been associated with heart failure, thromboembolic events, arrhythmias and sudden cardiac death. Earlier studies in the paediatric population suggested that approximately 50–60% of patients have left ventricular dysfunction with or without overt clinical heart failure at the time of diagnosis 1, 2 and that LV dysfunction is progressive over time with 89% of patients exhibiting LV impairment at 10 year follow up.1 At the time of writing the largest study of IVNC in adults is a series of 34 patients by Oechslin et al.3 In this study around 80% of patients were symptomatic at time of diagnosis (mean age at diagnosis 42 ± 17 years). Eighty-two percent had LV systolic dysfunction on echo and 100% of the 17 patients who had diastolic studies performed had confirmed diastolic impairment. Further more at 42 ± 40 months follow up 47% of patients had either died or undergone cardiac transplant for end stage heart failure. Systemic embolic events had occurred in 21% and documented ventricular tachycardia (VT) in 41%. These findings suggest that IVNC is a progressive condition with a poor prognosis in adulthood.
Cardiovascular magnetic resonance (CMR) has emerged as diagnostic tool with high spatial resolution and contrast. This technique affords high quality myocardial definition and it has been used as a gold-standard in the identification and characterisation of cardiac masses and cardiomyopathies. Recent reports have highlighted its utility in identifying and characterising the myocardial abnormalities in isolated left ventricular non-compaction. Previously, the reports suggesting a poor prognosis of IVNC have been potentially confounded by biases in method of identification (i.e. identified mainly in groups already presenting with clinical cardiovascular events and IVNC diagnosed secondarily). However, with improved detection by CMR we may identify IVNC prior to events and thus better understand its natural history. We present our consecutive experience of four cases of IVNC diagnosed in adulthood by cardiac magnetic resonance imaging (CMR) using Peterson's diagnostic criteria4 and confirmed echocardiographically, and discuss the clinical scenario around their identification, and the potential implications of this.
Section snippets
Case one
An asymptomatic 21-year-old man was referred to cardiology for further investigation after a soft systolic murmur was detected at a sports medical. On cardiovascular review no murmur was audible and physical examination was normal. Transthoracic echocardiography (TTE) revealed a thickened trabeculated LV apex and CMR scanning confirmed the diagnosis of IVNC. Left ventricular function was normal.
Case two
A 53-year-old man who was previously diagnosed in 1980 as suffering from hypertrophic cardiomyopathy
Results
IVNC was diagnosed in all four patients by CMR using the criteria described above (Figure 1, Figure 2). The diagnosis was also confirmed echocardiographically after retrospective review in patients 1, 2 and 4. However, the diagnosis of IVNC was not suspected in any of these four patients prior to the CMR study. Global LV systolic function was normal in patients 1 to 3 and only borderline to mildly reduced in patient 4. The diastolic indices for patient 1 were also normal as shown in Table 2
Discussion
IVNC is a rarely diagnosed condition. In the Oechslin study3 the majority of patients were tertiary referrals for further investigation of cardiovascular symptoms. The sample population in this study was therefore biased towards an initially sicker cohort of patients, and may explain the initial poor prognostic outcome associated with this condition. By contrast, IVNC was an incidental finding in patients 1 and 3 in our report, both of whom are asymptomatic. Patient 2 had had a documented
Summary
Isolated left ventricular non-compaction is becomingly increased identified, as high quality cardiac imaging such as CMR is becoming more accessible. The initial poor prognosis is likely affected by referral biases in the initial descriptions and a growing cohort of asymptomatic patients with this condition is being identified. Although the long-term outlook for this asymptomatic cohort of patients with IVNC is unknown, it may not be as sinister as first thought. Clearly, long-term follow-up in
Acknowledgements
We would like to thank Ms. Diana Pilkington and Ms. Kerry Brackenridge for their technical assistance with the CMR scans. No financial assistance was received for these case reports.
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