Acute Myocarditis Mimicking ST-segment Elevation Myocardial Infarction: Relation Between ECG Changes And Myocardial Damage As Assessed By CMR

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1 Acute Myocarditis Mimicking ST-segment Elevation Myocardial Infarction: Relation Between ECG Changes And Myocardial Damage As Assessed By CMR G. Nucifora 1, A. Di Chiara 2, D. Miani 1, G. Piccoli 3, M. Puppato 3, G. Slavich 1, D. Gasparini 3, A. Proclemer 1 Department of Cardiology and Radiology, University Hospital "Santa Maria della Misericordia", Udine, Italy (1,3) and Department of Cardiology, Tolmezzo Hospital, Tolmezzo, Italy (2)

2 None. CONFLICTS OF INTEREST

3 BACKGROUND The clinical presentation of AM is highly variable, ranging from subclinical disease to fulminant heart failure, cardiogenic shock and death. In a subset of patients, AM may have an infarct-like presentation (chest pain, ST-segment elevation on ECG and elevated troponin levels). In the setting of STEMI, previous MRI studies have demonstrated a relation between some ECG features (i.e. sumste, ST-segment resolution, residual ST-segment elevation and number of Q waves) with the extent of myocardial damage. Conversely, scarce data are available regarding the clinical meaning of ECG changes in the setting of infarct-like AM.

4 AIM The purpose of this study was to explore the relation between the ECG findings in patients with infarct-like AM and the extent of myocardial damage, as assessed by cardiac MRI.

5 METHODS - 1 A total of 41 consecutive previously healthy patients acutely admitted to our Institution because of acute-onset chest pain and ST-segment elevation on ECG, and with subsequent cardiac MRI findings consistent with AM according to Lake Louise criteria 1 were included in the study. 1. Friedrich et al. JACC 2009

6 METHODS T CMR protocol Breath-hold SSFP images (4CH, 3CH, 2CH, stack of short axis slices) Breath-hold, black-blood T2-W triple inversion-recovery sequence (4CH, 3CH, 2CH, short axis slices) Free breathing T1-weighted spin-echo sequence in 3 identical axial slices both before and after intravenous contrast injection Breath-hold, contrast-enhanced, inversionrecovery gradient-echo sequence (4CH, 3CH, 2CH, short axis slices) LV Volumes, EF, mass Myocardial edema (T2 SI Ratio) Myocardial hyperemia (EGE Ratio) Myocardial damage (%LV LGE)

7 METHODS - 3 Lake Louise Consensus Criteria for Myocarditis 1. Regional or global myocardial SI increase in T2W images 2. Increased global myocardial early gadolinium enhancement ratio between myocardium and skeletal muscle in gadolinium enhanced T1W images 3. 1 focal lesion with nonischemic regional distribution in IR gadolinium-enhanced T1W images (LGE) Friedrich et al. JACC 2009

8 METHODS - 4 ECG protocol 12-lead ECG was recorded at admission, at 12 hours, and every 24 hours thereafter until hospital discharge site of ST-segment elevation (anterior/non-anterior/diffuse) sumste time to normalization of ST-segment elevation development of pathologic Q wave development of negative T wave

9 RESULTS - 1 Clinical data n = 41 Age 36±12 Male gender 36 (88%) Family history CAD 7 (17%) Hypertension 5 (12%) Dyslipidemia 2 (5%) Diabetes Mellitus 2 (5%) Smoking 10 (24%) Flu-like symptoms 34 (83%) ctni (ng/ml) 11±10 CRP (mg/l) 75±69 ECG data n = 41 Site of ST-segment elevation - Anterior - Non-anterior - Diffuse 5 (12%) 33 (81%) 3 (7%) Sum of ST-segment elevation (mm) 5±3 Normalization of ST-segment elevation >24h 20 (49%) Development of pathologic Q wave 0 Development of negative T wave 28 (68%) CMR data n = 41 Left ventricular end-diastolic volume index (ml/m2) 73±11 Left ventricular ejection fraction (%) 65±7 N of left ventricular segments with myocardial edema 6±3 T2 ratio 1.98±0.30 EGE ratio 5.8±1.9 N of Left ventricular segments with LGE 5.6±3.4 %Left ventricle late gadolinium enhancement 9.6±7.2

10 LGE had a patchy pattern, with midmyocardial or sub-epicardial distribution in 49 (21%) and 183 (79%) LV segments, respectively. RESULTS - 2 topographic agreement = 47% topographic agreement = 59%

11 RESULTS - 3

12 RESULTS - 4 Univariate and multivariate regression analyses to determine the independent correlates of %LV LGE Univariate Analysis Multivariate Analysis β P value β P value Age Male gender Flu-like symptoms Left Ventricular Ejection Fraction Anterior or Diffuse ST-segment elevation 0.53 < Sum of ST-segment elevation 0.69 < <0.001 Normalization of ST-segment elevation >24h 0.63 < <0.001 Development of negative T wave 0.53 < <0.001

13 CONCLUSIONS - 1 Topographic agreement between site of LGE and site of STsegment elevation was only 59% and 47% among patients presenting with anterior or non-anterior ST-segment elevation, respectively. Consequently, ECG underestimates the extent of myocardial injury among patients with infarct-like myocarditis.

14 CONCLUSIONS - 2 The amount of ST-segment elevation (sumste), late normalization of ST-segment elevation (i.e. >24h) and development of negative T wave, were found to be significantly and independently related to the extent of LGE, suggesting that these ECG indexes could be used for a fast bed-side estimation of the extent of myocardial damage in this group of patients. This finding is novel in the setting of infarct-like myocarditis and parallels recent cardiac MRI observations in the setting of STEMI and Takotsubo cardiomyopathy.

15 CONCLUSIONS - 3 None of the patients included in the present study developed pathologic Q waves. Previous MRI studies have shown that the presence of Q wave in ischemic heart disease is mainly related to the extent of infarct size and, secondarily, to its transmural extent. Accordingly, the scattered nature and the absence of transmurality of myocardial damage in AM may explain the lack of development of Q waves in this group of patients.

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