Long-term outcome and its predictors in giant cell myocarditis

There are no studies focusing on prognostic factors in giant cell myocarditis (GCM). We aimed to identify predictors of transplant-free survival in GCM.

We analysed the details of 46 patients with GCM (31 women, mean age 51 ± 12 years) seen at our hospital since 1991 and followed for the occurrence of cardiac death or transplantation till May 2015. The association of transplant-free survival with patient characteristics, laboratory data on admission, and myocardial histology in the 38 patients diagnosed prior to death or transplantation was examined. Altogether 26 patients died (n = 8) or underwent transplantation (n = 18) a median of 11 months following symptom onset. The 5-year estimate of transplant-free survival was 42% [95% confidence interval (CI) 35-48%]. By Cox regression analysis, the hazard ratio for death or transplantation was 0.87 (95% CI 0.75-0.99) per +5% difference in LVEF, 1.06 (95% CI 1.03-1.10) per + 1000 ng/L difference in NT-proBNP, and 4.57 (95% CI 1.63-11.28) for cardiac troponin-T above the median of 85 ng/L at presentation. The severity of necrosis and fibrosis in myocardial biopsy, graded by the consensus of two cardiac pathologists as none, mild, moderate, or severe, predicted the outcome with a hazard ratio of 7.17 (95% CI 2.29-22.40) for the presence of either necrosis or fibrosis of at least moderate extent.

In GCM, the probability of transplant-free survival is 42% at 5 years from symptom onset. Markers of myocyte injury and cardiac dysfunction help predict the outcome.