Very long-term follow-up data of non-ischemic idiopathic dilated cardiomyopathy after beta-blocker therapy: recurrence of left ventricular dysfunction and predictive value of I-metaiodobenzylguanidine scintigraphy.

The management of idiopathic dilated cardiomyopathy (DCM) is well established. However, a subset of patients do not have recovery from or have recurrences of left ventricular (LV) dysfunction despite receiving optimal medical therapy. There are limited long-term follow-up data about LV function and the predictive value of iodine-123-metaiodobenzylguanidine (I-MIBG) scintigraphy, especially among the Japanese population. We retrospectively investigated 81 consecutive patients with DCM (mean LV ejection fraction (EF) 28 ± 7.5%) who had undergone I-MIBG scintigraphy before starting β-blockers. According to chronological changes in LVEF, study patients were classified into three subgroups: sustained recovery group, recurrence group, and non-recovery group. The outcome measure was cardiac death. Mean age was 59 ± 11 years and median follow-up was 11.5 (5.8-15.0) years. Thirty-six patients had recovery, 11 had recurrences, and 34 did not have recovery. The sustained recovery group had the best cardiac death-free survival, followed by the recurrence and non-recovery groups. Prolonged time to initial recovery was associated with recurrence of LV dysfunction. Large LV end-diastolic diameter and reduced heart to mediastinum ratio were associated with poor prognosis. In conclusion, with β-blocker therapy, 14% of patients showed recurrences of LV dysfunction. Thus, careful follow-up is needed, keeping in mind the possibility of recurrence, even if LVEF once improved, especially in patients whose time to initial recovery was long. I-MIBG scintigraphy provides clinicians with additional prognostic information.