The initially depressed left ventricular ejection fraction (LVEF) and HF symptoms improve in the majority of the ROCM patients under conventional HF treatment 2. However, chronic dilated cardiomyopathy (DCM) with persistently depressed LVEF and chronic HF can evolve 3. The mechanisms and factors responsible for the highly diverse evolution of ROCM, including myocarditis, are incompletely understood 4,5. The authors conclude that ROCM outcomes are generally favorable under contemporary HF medication, with rather lower than expected transplant free survival rates. Noticeably, the IMAC-2 trial reported a higher proportion of substantial LVEF improvement 10 EF units at 6 months (ca. 70%) compared to former studies (ca. 30-50%) 2, 6, 7, which indicates the efficacy of contemporary HF regimens, as well as the possibly higher adherence to treatment guidelines. Further major findings of the study are the adverse prognostic impact of higher LVEDD and of NYHA functional class IV at first presentation, and of African-American descent. In contrast, female gender was associated with improved outcome. These insights are consistent with the known better prognosis of women in heart failure 8, as well as with the known worse prognosis of African-Americans in HF 9, and the prognostic significance of LVEDD for myocardial recovery under assist device support 10. Thus, these demographic and echocardiographic data confirm that general CHF mechanisms equally apply to ROCM, and were undoubtedly important to be confirmed in this specific subgroup.
Acute myocarditis and DCM are etiopathogenically linked, mainly by persistence of cardiotropic viral infection and aberrant immune responses 3, 5. Comprehensive diagnostics of endomyocardial biopsies (EMB) have identified that the immunohistologically detected intramyocardial inflammation (as opposed to the histologically detected “active” or “borderline myocarditis”) 11-13 has adverse prognostic impact in AMC patients presenting with depressed LVEF 14. In selected patients, detection and persistence of viral genomes may be also relevant 15-17. These insights have been largely missed in the presented IMAC-2 trial, since EMB investigations were carried out in only 44 (12%) of the enrolled patients, and were subjected merely to histological evaluation, which revealed myocarditis in 10 (2.6%) subjects.
Furthermore, EMB investigations can be important for decision and timing of cardioverter-defibrillator (ICD) implantation 18. Of note, whilst the authors provide the information that n=28 (7.5%) patients had an ICD at study entry, no follow up data are presented for the ICDs implanted during follow up, which may be a surrogate or persistently depressed LVEF<35%. On the other hand, ICDs improve survival in HF patients substantially 19, and thus may have had substantial impact on prognosis in the IMAC-2 study, as well.
Late gadolinium enhancement (LGE) in cardiac magnetic resonance (CMR) has been associated to adverse outcome in DCM 20, 21. It would have been highly interesting to access the prognostic value of LGE and possibly also further CMR data for the specific subgroup of ROCM patients in the IMAC-2 study.
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