O1025: Evaluation of Imaging Findings and Clinical Outcomes Among Patients Referred for Ambulatory CMR Evaluation for Left Ventricular Noncompaction Cardiomyopathy

Background: Left ventricular noncompaction cardiomyopathy (LVNC) is thought to result from the arrest of normal compaction during cardiovascular development and is characterized by prominent trabeculations within the left ventricle. Although LVNC has been associated with adverse clinical outcomes, there is difficulty in discerning pathologic trabeculations diagnostic of LVNC from those reflecting normal variation. Prior literature has shown that a noncompacted:compacted (NC:C) ratio >2.3 by cardiac magnetic resonance (CMR) imaging in diastole is suggestive of pathologic LVNC. We sought to compare findings and clinical outcomes of ambulatory patients who satisfied this criterion versus those who did not. We hypothesized that patients with NC:C ratios of >2.3 would have decreased ventricular function, increased late gadolinium enhancement (LGE), and more frequent adverse clinical outcomes.

Methods: A retrospective cohort study was performed of patients who were referred for CMR at our center for suspected LVNC between 1/1/11 – 12/31/21. Patients with an echocardiogram, CMR, and clinic visit were included. An NC:C ratio was calculated by retrospective review of each CMR, and patients were divided according to presence (CMR+) or absence (CMR-) of a NC:C ratio of > 2.3. Demographic, EKG, echocardiographic, CMR, and clinical outcome data were collected for each patient. Data was compared between groups using standard univariate tests.

Results: This study included 51 patients of whom 30 (58%) had a NC:C ratio of >2.3 (CMR+). Patients were followed on average for 2.6 ± 2.9 years and were 14.0 ± 4.8 years old at the last follow-up. Of the cohort, 1/51 (2%) had stroke and 5/51 (10%) experienced an arrhythmia. There was no mortality, transplant, or need for mechanical support. Baseline characteristics between CMR+ and CMR- groups were similar (Table). There were no significant differences in echocardiographic or CMR measures of ventricular size or function between the groups. LV dysfunction was noted in 10% of subjects for both groups. There was no correlation between the NC:C ratio and left or right ventricular systolic function by CMR (Figure). There were no significant differences between groups when clinical characteristics and outcomes were compared individually or using a composite outcome (P-value = 0.68) of arrhythmia, stroke, VAD, transplant, or mortality (Table). Of patients tested for genetic abnormalities, 15/18 (83%) were positive with variants found in the MYH7, PDLIM3, and TTN genes.

Conclusion: Outcomes in patients referred for ambulatory CMR for evaluation of abnormal trabeculations are good, with low incidence of significant morbidity and no mortality in intermediate follow up. The severity of LVNC, as assessed by CMR NC:C ratio, does not distinguish subjects in terms of disease severity. This data suggests that a NC:C ratio > 2.3 is not useful in identifying patients at higher risk of adverse clinical outcome, though longer-term follow-up should be examined in this population.