P4659Left ventricular thrombus and arterial embolism in patients with noncompaction cardiomyopathy - Prognostic value of cardiac magnetic resonance imaging

Abstract Background Left ventricular noncompaction cardiomyopathy (LVNC) is characterized by an increased number of LV trabeculations with deep intertrabecular recesses. This abnormality is associated with heart failure, arrhythmias and arterial embolic events (AE). At present, it is unknown if AE is mainly due to blood stasis within the intertrabecular recesses, reduced LV ejection fraction or concomitant atrial fibrillation. LVNC is usually diagnosed by echocardiography but cardiac magnetic resonance imaging (CMRI) has evolved as an alternative method. This study assessed the prognostic value of CMRI for arterial embolic events in patients (pts) with LVNC. Methods 34 consecutive pts (19m, 15f, age 53±16) with LVNC underwent cine and contrast-enhanced CMRI with a 1.5 T scanner. LV diameter, volume, ejection fraction, and ratio of noncompacted to compacted myocardium (NC/C) were determined, and in 32 pts presence and localization of late gadolinium enhancement (LGE) was assessed. Clinical and CMRI findings were compared in pts with and without LV thrombus and/or AE. Results Overall, 20 pts (59%) were in heart failure NYHA III or IV, 14 (41%) had left bundle branch block (LBBB), 7 (21%) paroxysmal atrial fibrillation and 6 (19%) ventricular tachycardia (VT). By CMRI, LV diameter in end-diastole (66±8 mm), end-systole (53±10 mm), end-diastolic (229±69 ml) and end-systolic volume (150±68 ml) were enlarged and ejection fraction (36±14%) was reduced. The NC/C ratio was 3.2±1.4 in end-diastole and 2.6±1.4 in end-systole. One pt had right ventricular involvement with a thrombus. LGE was seen in 9/32 pts (28%) in the compacted myocardial layer (n=6), in the noncompacted trabecular layer (n=6) and within the papillary muscles (n=3). LGE was present in 3 areas in 1 and in 2 areas in 4 pts. In 3 pts (9%) a thrombus was seen within the trabecular layer which resolved under anticoagulation, and 6 additional pts (18%) without detectable thrombus experienced AE (transient ischemic attack n=1, stroke n=5). Thrombus and/or AE were not associated with age, sex, NYHA class, larger left atrial or LV diameter, LV volume, LBBB or documented VT. Atrial fibrillation (2/9 vs 5/25 pts, p=ns), LV ejection fraction (33±13% vs 38±15%, p=ns) and the NC/C ratio in end-diastole (median 3.2 vs 3) or end-systole (both median 2.6, p=ns) were similar. Thrombus and/or AE occurred mainly in pts with LGE (6/9 vs 2/23 pts, p=0.002). Conclusion In LVNC, evaluation by CMRI and demonstration of LGE in the compacted or noncompacted myocardium identifies patients at high risk for thrombus formation and/or arterial embolic events, warranting anticoagulation.