1 patient with an important LGE mass has died of rhythm disorders one year after symptoms onset. 2 patients recurred an episode of myocarditis. 1 patient (versus 9 patients on hospital time) kept reduced LVEF <50%.
DISCUSSION
In our study, we showed there was no correlation between STE or invT location and LGE areas on CMR. InvT patients had a lower LVEF and to present more transmural LGE. STE patients presented more frequent midwall LGE at baseline. On follow-up CMR, invT was related with larger extent of LGE. There was no relation between normal FU ECG and changes in LVEF and LGE extent or indexed left ventricular volumes and mass in follow-up. Nevertheless, patients with normal FU ECG had higher LVEF, lower indexed ventricular volumes and lower LGE extent compared with abnormal FU ECG.
Relation between ECG abnormalities and LGE on CMR
STE (n= 64, 62%) and invT (n= 21, 20%) were the most frequent ECG abnormalities on admission.
On the one hand, STE is expected in case of myocardial damage (notably transmural ischemia, or subepicardial injury) or pericardial inflammation. Others provided pathophysiological explanation (3), trying to assimilate STE in myocarditis to any coronary or vascular injuries. Nevertheless, the absence of direct relation of STE with neither LGE extent nor localization challenge these hypotheses. LGE extent was not different between STE pattern and non-STE pattern, while invT at follow-up showed larger extent of LGE.
On the other hand, T wave rely on both negative current of membrane repolarization combined with a repolarization vector that is opposite direction of depolarization. Their combination ends in a positive T wave that will be inverted in case of myocardial fibrosis (either due to ischemic or non-ischemic injury). invT appears to be related to inflammatory – that is
15 reported in the acute phase, LGE reflected mainly the increased distribution volume of contrast due to altered sarcolemnal permeability and tissue oedema whilst in the sub-acute phase LGE reflects predominantly permanent tissue damage (14).
Spatial correspondence between ECG findings and LGE areas on CMR
The locating value of ECG abnormalities remains controversial. In our study, LGE was overrepresented among inferior and lateral areas with an sub-epicardial distribution, as found in the literature (15),(16). Nevertheless, Ukena et al. described that repolarization abnormalities were neither associated with immunohistological signs of inflammation in patients with biopsy proven myocarditis (17). Di Bella et al. didn’t find relationship between ECG pattern and CMR location of myocarditis (15). We also showed here that there was no spatial correspondence between ECG and CMR findings, despite a 40 to 50% correlation of invT with LGE in the inferior and lateral wall (see figure 3), either at both acute and chronic stage of myocarditis. This suggest that ECG findings may be due to diffuse myocardial damage or pericardial inflammation.
Diagnostic value of ECG
The diagnostic value of ECG in myocarditis is limited. Aside from a low specificity, either ST-segment elevation or T-wave inversion were present as the most sensitive ECG criterions in 50% of patients, even during the first weeks of the disease (7). 18% of patients had a normal admission ECG and 68% in follow-up. We found similar results in the study of Chopra
et al. with 25% of hospital time ECG with normal repolarization (18). Florian et al. reported 19% of normal ECG (19) and Di Bella et al. reported 1/3 of normal ECG in patients with a recent acute myocarditis detected by CMR (15). Normal ECG is not the exact reflection of the damage caused within the myocardium. Nevertheless, it remains an interesting diagnostic tool.
Consequently, a normal ECG does not exclude the diagnosis in patients with appropriate symptoms (20).
ECG Findings in monitoring acute viral myocarditis
Monitoring acute myocarditis requires symptoms relief, drug management and prognostic assessment against long-term adverse outcomes, mainly driven by ventricular arrythmia with sudden cardiac death and cardiac remodeling with heart failure. Yet the expected course of acute viral myocarditis is usually benign (21) but the body of proof in this field is scarce. To our knowledge, no studies assessed the value of normal ECG in the up. We showed that a normal ECG did not mean complete healing. Indeed, during the follow-up, while changes in LVEF, LV volumes and myocardial mass improved favourably, there was a decrease but persistence in LGE extent. Change in CMR parameters did not correlate with ECG finding, including FU-ECG. Nevertheless, patients with normal ECG had significantly higher LVEF, lower myocardial volumes, and lower LGE mass.
Some studies have shown the prognostic impact of CMR damage and the prognostic value of ECG abnormalities. QRS abnormalities (duration, Q wave) appear to be related to the prognostic of myocarditis with lower LVEF (17), (22), (23). Contrary to Chopra et al. who suggested STE – as an infarct-like pattern of myocarditis – to be associated with MACE occurrence (18). Our STE patients presented a trend for smaller LGE extent and higher LVEF
17 while invT pattern related with lower LVEF and greater LGE extent. Gräni et al. showed LGE extent (per 10% increase) corresponded to a 79% increase in risk of MACE (8). LGE is prognostic. In follow-up, InvT may be bad prognostic because they are correlated with LGE extent; it could be a surrogate marker for prognosis in myocarditis.
Strengths of the study
Both ECG and CMR were specifically analysed on purpose of this study, blinded to clinical data. Concerning ECG and CMR analysis, we had a very good correlation with the current literature; but none of the studies performed these data on longitudinal follow-up.
Study limitations
In the first place, this is a retrospective study on a small population with the biases that implies. Follow-up ECG were not specifically obtained the same day as follow-up CMR. A large prospective study should be required to best determine the prognosis of the ECG in acute myocarditis follow-up to end up with cardiovascular outcomes. There is no clear definition for cardiac healing after myocarditis (21).
Secondly, our results are set on a population of myocarditis with preserved LVEF and conclusions apply to these patients only.
Thirdly, we have no data about viral aetiology, whereas specific LGE patterns have been described and may interfere with our results (24).
CONCLUSION
STE and invT were the most frequent ECG abnormalities in patients with CMR-proven myocarditis. A normal ECG did not exclude the diagnosis, neither complete healing. While STE and invT correlated with LGE pattern, there was no spatial correspondence between STE or invT and LGE areas on CMR, but invT presence related with greater extent of LGE at follow-up. Further studies are needed to determine whether invT may be considered as a surrogate marker for prognosis in myocarditis.
19
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LISTE DES FIGURES
Figure 1: Flow chart ... I Figure 2: 12 leads ECG abnormalities obtained in admission. ... II Figure 3: Spatial correspondence between ECG findings and LGE areas on CMR………. III
23
LISTE DES TABLEAUX
Table I: Patients included in a follow-up analysis: Baseline characteristics related to STE and invT on hospital discharge ECG (ECG 2) ... IV Table II: ECG findings during follow-up ... V Table III: Relation between baseline and follow-up ECG findings and CMR parameters ... VI Table IV: Follow-up: Changes in CMR parameters according to FU ECG findings. ... VII
TABLE DES MATIÈRES
ECG abnormalities and CMR parameters ...11
3.1. Baseline: CMR findings and correlation with STE and invT ...11
3.2. Follow-up: CMR findings and correlation with STE and invT ...12
Follow-up ...12
4.1. Normal FU ECG and changes in CMR parameters ...12
4.2. Outcomes ...13
DISCUSSION ... 14
Relation between ECG abnormalities and LGE on CMR ...14
Spatial correspondence between ECG findings and LGE areas on CMR ...15
Diagnostic value of ECG ...15
ECG findings in monitoring acute viral myocarditis ...16
Strengths of the study ...17 Figure 2: Baseline: 12 leads ECG findings. ... II Figure 3: Spatial correspondence between ECG findings and LGE areas on CMR. ... III Table I: Patients included in a follow-up analysis: Baseline characteristics related to STE and invT on hospital discharge ECG (ECG 2) ... IV Table II: ECG findings during follow-up ... V Table III: Relation between baseline and follow-up ECG findings and CMR parameters ... VI
I
ANNEXES
Figure 1: Flow chart
103 patients screened with acute myocarditis confirmed by clinical data
and CMR
62 patients with follow-up CMR
25 patients did not have a follow-up CMR
103 patients with admission and discharge ECG
87 patients with follow-up ECG
Figure 2: Baseline: 12 leads ECG findings.
a) Concave and diffuse STE , b) Convex and infero-latero-apical STE/anterior mirror reflection, c) infero-lateral invT and septal STE.
a)
b)
c)
III
Figure 3: Spatial correspondence between ECG findings and LGE areas on CMR.
A) STE:
Spatial correspondence between LGE areas and STE was 35% on baseline and 3%on follow-up.
Baseline Follow-up
B) InvT:
Spatial correspondence between LGE areas and invT was 29% on baseline and 18% on follow-up.Baseline Follow-up
Table I: Patients included in a follow-up analysis: Baseline characteristics related to STE and invT on hospital
discharge ECG (ECG 2)
He following numbers were available for the laboratory testing: troponin I n=46 (12 missing), troponin T n=15 (47 missing), C reactive protein n=58 (4 missing).
Data are presented as the mean value±SD, number (%) of subjects or median (interquartile range).
P values are given to compare STE or invT patients with non-STE and non-invT patients, respectively.
CRP: C-reactive protein, ACE: angiotensin-converting enzyme, ARB: angiotensin receptor blockers, VT:
ventricular tachycardia, VF: ventricular fibrillation, NA: not available.
All patients Peak troponin T, µg/l (n=15)
CRP, mg/l (n=58)
V
Table II: ECG findings during follow-up
BBB, bundle branch block.
Data are presented as the mean value±SD or number (%) of subjects.
Data were available for 1 patient about STE and invT characteristics.
ECG characteristics ECG 1
(n=103) ECG 2
(n=103) FU ECG
(n=87)
Timing Admission Hospital
discharge 4.4±3 months
tachycardia/ventricular fibrillation 7 (7) 0 (0) 0 (0)
PQ segment depression 17 (17) 4 (4) 0 (0)
Table III: Relation between baseline and follow-up ECG findings and CMR parameters
Data are presented as the mean value±SD or number (%) of subjects or median (interquartile range).
He following numbers were available for Heart rate: n=57 patients (5 missing)
ECG characteristics
CMR parameters Total STE No STE p invT No invT p
T0 CMR ECG 2 (Hospital discharge)
Generic data n=62 n=20 n=42 n=22 n=40
Delay symptoms onset to T0 CMR,
days 9 (4-17)
Delay T0 CMR-FU CMR, days 100 (91-125) Delay FU ECG-FU CMR, days 51 (27- 86)
VII
Table IV: Follow-up: Changes in CMR parameters according to FU ECG findings.
Data are presented as the mean value±SD.
Changes in CMR parameters
(%) Total
n=62 Normal FU ECG
n=42 Abnormal FU ECG
n=20 p
LVESVI, % -9±18 -8±20 -9±12 0.771
LVEDVI, % -3±13 -2±14 -5±10 0.362
LVEF, % 9±21 8±16 11±29 0.649
LGE extent, % -38±34 -41±29 -34±40 0.501
LVMI, % -8±8 -9±7 -8±9 0.503
IX
PERAULT Camille
Anomalies ECG pendant un épisode de myocardite aigüe et son suivi, au-delà de la valeur diagnostique.
Mots-clés : ECG, IRM cardiaque, myocardite aigüe virale, sus décalage ST, onde T négative.
ECG abnormalities during an episode of acute myocarditis and its follow-up beyond the diagnostic value.
Keywords: ECG, CMR, acute viral myocarditis, ST segment elevation, T wave inversion.
RÉSUMÉ
Introduction : Peu d’études ont décrit les modifications ECG dans la myocardite. L’IRM cardiaque est actuellement le meilleur outil diagnostique et prognostique dans la myocardite.
L’objectif est de corréler les résultats ECG et IRM cardiaques, leurs variations et d’évaluer si l’ECG est un outil fiable pour identifier la guérison myocardique.
Méthode : Nous avons réalisé une étude rétrospective entre Janvier 2008 et Juillet 2018 sur 103 patients présentant une myocardite aiguë virale confirmée par l’IRM cardiaque. Le suivi ECG et IRM cardiaque était obtenu chez 62 patients.
Résultats : Le sus décalage du segment ST (sus ST) (n= 64, 62%) et l’onde T négative (n= 21, 20%) étaient les anomalies ECG prédominantes. La population comportait 56 hommes âgés en moyenne de 33 ans présentant pour 92% une douleur thoracique à l’admission et pour 63% un syndrome infectieux récent. La population avec onde T négative était plus âgée (p=0.022). Il n’y avait pas de corrélation entre le sus ST ou l’onde T négative et la localisation du rehaussement tardif en IRM. Les patients avec ondes T négatives avaient une FEVG plus basse (p=0.029) et présentaient plus de rehaussement tardif transmural (p=0.032). Les patients avec sus ST avaient davantage de rehaussement tardif medio-ventriculaire. Dans le suivi, les patients avec onde T négatives (n=10) avaient un rehaussement tardif plus étendu (p=0.002). En comparant les patients avec un ECG normal ou anormal dans le suivi, il n’y avait pas de différence concernant les variations de FEVG (p=0.649), de rehaussement tardif (p=0.501), de volumes et masses ventriculaires indexés (respectivement, (DTSVG : p=0.771), (DTDVG : p=0.362), (masse VG : p=0.503)).
Conclusion : On ne retrouvait aucune différence d’évolution des paramètres IRM entre les patients avec ECG normal ou anormal dans le suivi. Un ECG normal ne permettait pas d’exclure le diagnostic à l’admission ni d’affirmer la guérison dans le suivi. Le sus ST et l’onde T négative étaient corrélés au phénotype myocardique mais ne localisaient pas les dommages myocardiques. Néanmoins, dans le suivi, les ondes T négatives témoignaient d’un rehaussement tardif plus conséquent. Les ondes T négatives pourraient être un marqueur de substitution dans le pronostic des myocardites.
AB ST RACT
Introduction: There are few studies to describe the changes in ECG findings during myocarditis. Cardiac magnetic resonance (CMR) is on top of acute diagnosis and prognosis after myocarditis, providing new insights into myocardial healing and phenotypes.
The objective of this study was to correlate ECG findings with acute myocarditis CMR phenotype and changes over time and to assess whether ECG is a significant tool to identify healed myocarditis.
Methods: We performed a retrospective analysis of 103 patients who presented CMR-proven acute viral myocarditis between January 2008 and July 2018. Follow-up ECG and CMR were obtained in 62 patients.
Results: ST segment elevation (STE) (n= 64, 62%) and T wave inversion (invT) (n= 21, 20%) were the most frequent ECG abnormalities on admission. Mean age was 33±16 years. 56 patients (86%) were male. 39 (63%) presented with recent infectious syndrome. 57 (92%) had chest pain on hospital admission. InvT patients were older (p=0.022). There was no correlation between STE or invT location and LGE areas on CMR. InvT patients had a lower LVEF (p=0.029) and presented more transmural LGE (p=0.032). STE patients presented more frequent midwall LGE. On follow-up CMR, invT (n=10) was related to larger extent of LGE (p=0.002). There was no difference between patients with normal ECG and abnormal ECG about changes in LVEF (p=0.649), LGE extent (p=0.501), LVEDV index (p=0.362), LVESV index (p=0.771) and LVM index (p=0.503).
Conclusion: There was no significant difference in the regression of pre-existing CMR abnormalities between the normal and abnormal ECG group during follow-up. A normal ECG did not exclude the diagnosis, neither complete healing. STE and invT correlated with LGE pattern. Despite the absence of spatial correspondence between ECG and CMR findings, invT presence related with greater extent of LGE at follow-up. InvT might be considered as a surrogate marker for prognosis in myocarditis.