The prognostic impact of follow-up cardiac Metaiodobenzylguanidine imaging: relation to differential trajectories in left ventricular ejection fraction after acute decompensation

Cardiac metaiodobenzylguanidine (MIBG) imaging provides prognostic information in patients with heart failure (HF). Recently, the trajectory of left ventricular ejection fraction (LVEF) has been focused in patients with reduced LVEF admitted for acute decompensated heart failure (ADHF). We sought to prospectively investigate the prognostic value of the follow-up cardiac MIBG imaging in ADHF patients with reduced LVEF, in relation to LVEF trajectory.

We prospectively studied 145 ADHF patients with reduced LVEF<40%. The cardiac MIBG heart-to-mediastinum ratio (late HMR) was measured on the delayed image at the discharge and 6 months’ follow-up (6FUP). HF recovered LVEF (HFrecEF) was defined as those with a second measurement of LVEF at 6FUP of ≥ 40% with a 10-point increase from baseline LVEF, according to the previous report. Furthermore, in the present study, HFrecEF was classified into the two groups; patients with partial recovery of LVEF (≥40%, <50%) (HFparEF) and complete recovery of LVEF (≥50%) (HFcorEF). The endpoint was a cardiac event (CE) defined as a composite of cardiac death and unplanned hospitalization for worsening HF.

At 6 months after the discharge, HFrecEF was observed in 97 (67%) of 145 study patients and the remaining 48 (33%) patients did not have HFrecEF (HFnorEF). In the subgroup of HFrecEF, 43 (30%) patients had HFparEF and 54 (37%) patients had HFcorEF. Late HMR at 6FUP in HFcorEF patients was significantly greater than those in HFparEF and HFnorEF patients, which was also observed at the discharge with non-significant difference. The change of late HMR significantly correlated with the improvement in LVEF (r=0.33, p<0.001). During a follow-up period of 4.3 ± 2.6 years, 28 patients in HFnorEF, 11 patients in HFparEF and 4 patients in HFcorEF had CEs, respectively. Kaplan-Meier analysis revealed that HFnorEF patients had a significantly higher risk of cardiac events than those with HFparEF and HFcorEF. (58.3% vs 25.6% vs 7.4% P < 0.0001). Patients with lower late HMR at 6FUP had a greater risk of CEs than those with higher late HR at 6FUP in HFrecEF, especially in HFparEF, which was not observed in HFnorEF subgroup.