Prediction of adverse cardiac events in dilated cardiomyopathy using cardiac T2* MRI and MIBG scintigraphy

Iron deficiency and cardiac sympathetic impairment play a role in the worsening of heart failure, and these two conditions may be linked. The present study aimed to clarify the relationship between myocardial iron deficiency, cardiac sympathetic activity, and major adverse cardiac events (MACE) in patients with dilated cardiomyopathy (DCM). Cardiac T2* MRI for iron deficiency and ¹²³I-Metaiodobenzylguanidine (MIBG) imaging for cardiac sympathetic activity were performed in 46 patients with DCM. Myocardial T2* value (M-T2*) was calculated by fitting signal intensity data for mid-left ventricular septum to a decay curve using 3-Tesla scanner. ¹²³I-MIBG washout rate (MIBG-WR) was calculated using a polar-map technique with tomographic data. We analyze the ability of M-T2* and MIBG-WR to predict MACE. MIBG-WR and M-T2* were significantly greater in DCM patients with MACE than in patients without MACE. Receiver-operating-characteristics curve analysis showed that the optimal MIBG-WR and M-T2* thresholds of 35 % and 28.1 ms, and the two combination predict MACE with C-statics of 0.69, 0.73, and 0.82, respectively. Patients with MIBG-WR <35 % and M-T2* <28.1 ms had significantly lower event-free rates than those with MIBG-WR ≥35 % or M-T2* ≥28.1 ms (log-rank value = 4.35, p < 0.05). Cox hazard regression analysis showed that χ² and the hazard ratio were 3.99 and 2.15 for development of MACE in patients with MIBG-WR ≥35 % or M-T2* ≥28.1 ms (p < 0.05). Iron deficiency, expressed by a high M-T2*, and MIBG-WR were both independent predictors of MACE in patients with DCM. The two combination was a more powerful predictor of MACE than either parameter alone.