CMR verified myocarditis leads to lower EF at 12 months
In a small group of patients, cardiovascular magnetic resonance (CMR) imaging provided clues to myocarditis diagnosis and outcomes. Positive “Lake Louise criteria” (LL) was associated with improved left ventricular function recovery, while patients with a negative LL still had lower ejection fraction (EF) at 12 months.
These findings were published in the October issue of the European Heart Journal.
Emmanuelle Vermes, MD, of the Stephenson Cardiovascular MR Centre and the Libin Cardiovascular Institute of Alberta in Calgary, and colleagues saw distinct patterns of recovery through LL CMR evaluation of 37 patients.
In order for a patient to be considered positive for myocarditis by LL criteria, two of three findings needed to be made including global or regional myocardial edema with a signal intensity of at least 2 standard deviations above normal tissue, capillary leakage shown through gadolinium uptake and/or non-ischemic irreversible myocardial injury.
“Among these criteria, the presence of regional or global myocardial [edema] was the strongest predictor indicating that the observed improvement of systolic function reflects recovery of reversibly injured myocardium,” Vermes et al wrote.
They found that in patients that met LL criteria, baseline and 12 month EF were lower, but increased by follow-up. They also found that regional or global myocardial edema was an indicator of an increase in EF by five percent or more.
Additionally, they noted that edema was a strong and independent predictor for EF increase. Edema also was able to predict a decrease in end-systolic volume, Vermes et al wrote.
“We also observed that the extent of high intensity areas in LGE [Late gadolinium enhanced] images decreased over time. We, however, found a smaller amount of LGE and observed complete resolution of LGE in a larger proportion of patients. The difference between these observations can be explained by less severe disease and by shrinkage of small scars below the detectability threshold.”
While these findings are promising, due to the small size of the patient cohort, Vermes et al noted that there may be additional relationships between criteria and functional outcomes that were not observed by their team.