LVEF rose from 0.24±0.08% at entry and 0.40±0.12% at 6 months (mean LVEF increase: 17±13%). At 6 months, 70% of the patients demonstrated an increase of >10 EF units, and 39% demonstrated an increase of > 20 EF units. 40% had an LVEF of 0.45 or more at 6 months, and the LVEF had normalized (> 0.50) in 25% of the patients. Transplant-free survival at 1, 2, and 4 years was 94%, 92%, and 88%, respectively. Furthermore, survival free of heart failure hospitalization was 88%, 82%, and 78%, respectively.
NYHA functional class IV was associated with a significantly higher risk of death/transplantation over 4 years of follow-up. In contrast, female sex was associated with a significantly lower risk of death/transplantation. In analyses adjusted for sex, baseline LVEF, and blood pressure, LVEF at 6 months was significantly lower in African-Americans (p=0.02). A smaller left ventricular end-diastolic diameter (LVEDD; determined by transthoracic echocardiography) at first presentation was the strongest predictor of LVEF at 6 months (p<0.0001).
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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