Background: The prognostic value of myocardial fibrosis as quantified by magnetic resonanvce imaging (MRI) in patients with ischemic and non-ischemic cardiomyopathy is well known; however, little information is available regarding its prognostic value in patients with acute myocarditis. In addition, there are limited data regarding the time period required to restart physical activity after acute myocarditis.
Methods: In patients hospitalized with acute myocarditis we suggest a cardiac rehabilitation protocol based on the percentage of left ventricular (LV) myocardial fibrosis: patients with myocardial fibrosis > 5% and ≤ 5% of the total LV myocardial mass were allowed to participate on cardiac rehabilitation program 6 and 3 months; respectively, after the diagnosis of acute myocarditis.
Results: Twenty eight patients were prospectively included, one patient did not perform cardiac MRI due to claustrophobia, and therefore 27 patients (33.5 ± 12.5 years, 89% men) were included. Quantitative analysis revealed myocardial fibrosis of 11.6 ± 15.2g (7.8 ± 9% of the left ventricular mass) which was mainly localized to the basal infero-lateral segments. Mean myocardial edema was 17.8 ± 20.1g (11.9 ± 10.6% of the left ventricular mass) which was more extensive and involved apical and septal segments as well. Right ventricular involvement was found in 3 patients (11%), and the left and right ventricular ejection fraction was 54 ± 9% and 50 ± 10%, respectively. Mean peak troponin and CRP level were 12 ± 19 mcg/l and78 ± 73 mg/l, respectively. A total of 8 patients had myocardial fibrosis > 5% and therefore participate on cardiac rehabilitation program 6 months after the diagnosis of acute myocarditis and 20 patients had myocardial fibrosis ≤ 5% and therefore participate on cardiac rehabilitation after 3 months. No patients develop ventricular arrhythmia or cardiac death during the rehabilitation program.
Conclusion: The present ongoing study demonstrated the use of myocardial fibrosis, as quantified by cardiac MRI, to determine the time period to restart physical activity in patients after acute myocarditis.
