The spectrum of electrocardiographic manifestations of acute myocarditis: An expanded understanding

Abstract

Background and PurposeDescriptions of the significance of ST segment or QRS abnormalities in myocarditis are limited because documentation of the diagnosis has previously required myocardial biopsy. Late gadolinium enhancement (LGE) and T2 weighted imaging in the midventricular wall on cardiac magnetic resonance imaging (CMRI) has a very good positive predictive value for the diagnosis of myocarditis. We hypothesized to reexplore the diagnostic value of these electrocardiographic (ECG) changes in myocarditis by utilizing CMRI as the reference standard. MethodsData on demographics, clinical presentation, laboratory tests, echocardiograms, coronary angiograms, and computed tomography angiography of 41 consecutive patients with definite midventricular or subepicardial LGE and T2 weighted imaging on CMRI were extracted from the available clinical records. ECGs were blindly examined by two independent readers and divided based on (a) STT changes into: 1. No STT changes, 2. STT changes but no ST elevation, 3. ST elevation (STE); and (b) the presence or absence of QRS abnormalities. Associations of these ECG changes with differences in left ventricular ejection fraction, as measured from CMRI was the main aim of this study. In addition, a complete clinical profile of these patients with myocarditis as identified by CMRI was also created. Results80% of our study population were male with a mean age of 38.6±15.5 and a paucity of traditional cardiovascular risk factors (<30%). 90% presented with chest pain with more than half having dyspnea and a viral prodrome, but fever was infrequent (15%). Peak troponin-I and creatine kinase-MB levels exceeded the upper limit of normal in latest 85%, often by more than 5 times the limit. 18% had a coronary luminal narrowing of ≥50%, while 56% had echocardiographic wall motion abnormalities. The left ventricular ejection fraction averaged 54.3±10.8%. In 24.4% of patients, the ECG was entirely normal; while 39% had STE. STT changes did not detect any differences in the ejection fraction. An abnormal QRS, which was present in 29%, was associated with a lower left ventricular ejection fraction (p=0.005). ConclusionsPatients with clinical features suggestive of myocarditis and confirmatory CMRI findings, can present with a variety of ECG findings, some of which have the potential to identify those with a worse cardiac function, and potentially with a worse prognosis.