ONLINE APPENDIX
Methods
Cardiovascular magnetic resonance
All cine-images were acquired using a balanced steady-state free precession sequence in
combination with parallel imaging (SENSitivity Encoding, factor 2) and retrospective gating during a
gentle expiratory breath- hold (TE/TR/flip-angle: 1.7ms/3.4ms/60°, spatial resolution 1.8x1.8x8 mm).
Dark blood T2 imaging for oedema was performed using a STIR sequence with whole- heart coverage of
short-axis slices [7,12]. LGE imaging was performed using gapless whole heart coverage of short axis
slices ~20 minutes after administration of 0.2 mmol/kg body weight gadobutrol (Bayer Healthcare,
Leverkusen, Germany) using a T1 weighted mid-diastolic inversion recovery sequence with a patientadapted prepulse delay. Balanced steady state free precession, single breath-hold modified Look-Locker
imaging (MOLLI) was used for T1 mapping and performed in a single midventricular short axis slice,
prior to contrast administration and to scar imaging, respectively (TE/TR/flip-angle (FA):
1.64msec/3.3msec/50°, voxel size 1.8 x 1.8 x 8 mm, phase encoding steps n=166, 11 images from three
inversions (3+3+5) with three-heartbeat pauses prior to the second and third inversions and an adiabatic
prepulse), as previously described [22,23].
Image analysis
All routine CMR analysis was performed on commercially available software (CircleCVI 42®,
Calgary, Canada). Endocardial LV borders were manually traced at end-diastole and end-systole. The
papillary muscles were included as part of the LV cavity volume. LV end-diastolic (EDV) and endsystolic (ESV) volumes were determined using Simpson’s rule. Ejection fraction (EF) was computed as
EDV-ESV/EDV. All volumetric indices were normalized to BSA.
T2 images were visually assessed for the presence of regionally SI as previously described [7].
Increased T2 signal intensity and edema ratio were examined using predefined tissue characterisation
modules (CircleCVI®, Calgary, Canada) [7,12].
LGE images were visually examined for the presence of regional fibrosis showing as bright areas
within the myocardium in corresponding longitudinal views and by exclusion of potential artefacts [12].
Myocardial T1 relaxation was measured in midventricular short axis slice conservatively within
the myocardium, as previously described [22-24]. Care was taken to avoid contamination with signal
from the blood pool and areas of visualized LGE. Following offline image co-registration and motion
correction, T1 values were determined by fitting an exponential model to the measured data applying
Look-Locker, noise and heart rate correction. In addition to the T1 measurements of native myocardium
and blood pool, we calculated the gadolinium myocardial partition coefficient (λ) according to the
formula [25]:
a. λ =[Δ R1myocardium ]/[ Δ R1bloodpool] pre and post Gd contrast
Results
Clinical characteristics
Table S1 summarizes the characteristics of the study cohort. Patients with acute myocarditis
underwent the CMR study within a median of 5 days (range =7 days), whereas subjects in the
convalescent group presented on average 6 months (range =2 months) after the onset of the symptoms.
All groups had predominance of males. Groups were similar for age, blood pressure, heart rate or
traditional cardiovascular risk factors. Both patient groups presented with a variety of cardiovascular
symptoms: patients with acute myocarditis reported more breathlessness, whereas patients in the
convalescent group had a higher frequency of unexplained syncope. A total of 5 patients presented with
life-threatening arrhythmia or aborted cardiac arrest, 4 of them in the acute stage.
Online Table 1: Patients baseline characteristics. BP – blood pressure; CRP – C-reactive protein.
*Counts for soluble markers refer to the acute presentation. One-way ANOVA or Kruskal-Wallis, as
appropriate for the type of the data, P<0.05 is considered significant
Variable
Controls
Acute
Convalescent
Sig.
(n=40)
myocarditis
myocarditis
(P-
(n=61)
(n=67)
value)
Age, years
45 ± 15
48 ± 17
48 ± 14
0.6
Gender (male, n,%)
21 (53)
32 (60)
34 (61)
0.6
25± 5
26 ± 4
26 ± 4
0.7
BP systolic (mmHg)
125 ± 16
122 ± 26
125 ± 20
0.7
BP diastolic (mmHg)
78 ± 10
73 ± 11
78 ± 11
0.2
Heart rate (bpm)
68 ± 12
70 ± 14
69 ± 11
0.7
Type 2 Diabetes mellitus, n (%)
2 (5)
6 (10)
2 (3)
0.3
Hypertension, n (%)
8 (20)
12 (20)
16 (24)
0.7
5 (12.5)
10 (16)
8 (12)
0.9
Smoker, n (%)
4 (10)
7 (13)
8 (12)
0.9
Increased CRP, n (%)*
0 (0)
56 (92)
5 (7)
0.001
Increased Troponin T, n (%)*
0 (0)
58 (95)
8 (12)
<0.0001
90±20
80±29
84±13
0.9
Body mass index (kg/m2 )
Hypercholesterolemia, n (%)
eGFR, mL/min per m2
Online Table 2. CMR findings in the independent testing cohorts (A –patients with serial scans, B –
external validation cohort) *significant differences between patients with myocarditis compared to
controls, §for between the disease groups.
A Serial cohort (n=37)
1.5 T (n=16)
Controls
Acute
Convalescent
Sig.
myocarditis
myocarditis
(p- value)
(n=18)
Native T1 (msec)
940±20
1067±45*
994±21*§
<0.01
Postcontrast T1 (msec)
422±68
408±54*
435±37
0.002
Λ, λ (%)
42±4
51±7*
43±7
0.01
3T (n=21)
(n=22)
Native T1 (msec)
1045±19
1190 ± 67*
1095 ± 48*§
<0.001
Postcontrast T1 (msec)
449±61
401 ±65*
431±53
0.004
Λ, λ (%)
44±9
51±7*
44±6
0.006
Controls
Acute
Convalescent
myocarditis
myocarditis
(n=24)
(n=26)
(n=18)
(n=10)
(n=13)
Native T1 (msec)
940±20
1075±48*
991±28*§
<0.001
Postcontrast T1 (msec)
422±68
411±67*
441±57
0.007
Λ, λ (%)
42±4
52±8*
42±8
0.01
(n=22)
(n=14)
(n=13)
Native T1 (msec)
1045±19
1211±51*
1092±41*§
<0.001
Postcontrast T1 (msec)
449±61
409 ±54*
422±53
0.003
Λ, λ (%)
43±7
53±9*
44±6
0.009
B Validation sample (n=52)
1.5 T
3T
Online Table 3. Binary logistic regression. Univariate and multivariate binary logistic regression
testing A- discrimination between health and disease (all patients with clinically suspected myocarditis)
and B—discrimination between acute or convalescent myocarditis. Chi-Square for Mantel-Haenszel tests;
p-values for Fisher exact tests. OR – odds ratio.
A. Healthy vs. all subjects with myocarditis
Variable
Chi2
OR
Sig.
Sensitivity
Specificity
Discriminatory
(95%CI)
(p-value)
(95%CI)
(95%CI)
accuracy
(95%CI)
Univariate analysis
LV-EF
17.9
0.92 (0.88-
<0.001
94 (92-97)
10 (5-32)
72 (68-77)
0.96)
LV-EDV
8.9
1.03 (1.0-1.1)
0.01
96 (94-98)
9 (4-16)
72 (68-75)
LV-ESV
14.2
1.05 (1.0-1.1)
0.04
97 (94-99)
9 (3-14)
72 (68-74)
LV-mass
18.9
1.06 (1.07-
<0.001
97 (96-99)
26 (14-36)
76 (72-82)
<0.001
89 (81-92)
9 (4-16)
71 (61-82)
1.1)
Edema ratio
18.4
12.9 (2.3-56)
1.5 Tesla
36.94
1.10 (1.0-1.09)
0.003
93 (85-96)
83 (67-97)
91 (79-96)
3 Tesla
93.86
1.19 (1.1-1.3)
0.001
96 (90-98)
89 (76-96)
94 (86-99)
0.01
92 (74-93)
35 (16-46)
77 (61-81)
0.02
95 (77-97)
42 (21-61)
79 (69-85)
Native T1
Postcontrast T1
1.5 Tesla
8.02
1.02 (1.01.04)
3 Tesla
1.52
1.01 (1.01.02)
Multivariate analysis (forward stepwise)
1.5T
Native T1
30.01
1.09 (1.03-1.15)
<0.01
94 (86-97)
83 (72-89)
91 (82-98)
Chi-Square=35.1, p<0.001; Wald=9.63; -2 Log likelihood=15.7, Nagelkerke R2=0.81.
Variables not included in the model
Postcontrast T1
0.31
LGE (present)
0.06
Increased T2
0.11
signal (present)
Edema ratio
0.16
LV-mass
0.32
LV-EF
0.46
LV-EDV
0.94
LV-ESV
0.72
3T
Native T1
87.41
1.3 (1.06-
<0.01
96 (93-100)
96 (81-100)
97 (91-99)
1.48)
Chi-Square=86.6, p<0.001; Wald=7.14; -2 Log likelihood=13.7, Nagelkerke R2=0.92.
Variables not included in the model
Postcontrast T1
0.61
LGE (present)
0.16
Increased T2
0.29
signal (present)
Edema ratio
0.19
LV-mass
0.23
LV-EF
0.13
LV-EDV
0.34
LV-ESV
0.21
B. Acute vs. convalescent myocarditis
Variable
Chi2
OR
Sig.
Sensitivity
Specificity
Discrimina
(p-value)
(95%CI)
(95%CI)
tory
(95%CI)
Accuracy
(95%CI)
Univariate analysis
LV-mass index
10.1
1.04 (1.02-1.06)
0.003
57 (46-76)
70 (60-79)
63 (53-73)
Edema ratio
27.07
5.33 (1.8-16.2)
0.001
62 (48-73)
77 (68-86)
70 (58-79)
Increased T2
19.38
9.78 (3.15-30.3)
<0.001
64 (54-71)
85 (70-94)
73 (61-80)
1.5 Tesla
40.3
0.85 (0.74-0.94)
0.01
96 (85-99)
93 (76-99)
95 (81-99)
3 Tesla
65.7
0.86 (0.79-0.93)
<0.001
97 (86-100)
95 (86-97)
96 (86-98)
92 (68-99)
94 (89-98)
signal
Native T1
Multivariate analysis (forward stepwise)
1.5T
Native T1
28.1
1.14 (1.07-1.4)
0.02
95 (80-100)
Chi-Square=25.8, p<0.001; Wald=5.6; -2 Log likelihood=15.3, Nagelkerke R2=0.77.
Variables not included in the model
Postcontrast T1
0.61
LGE (present)
0.69
Increased T2
0.28
signal (present)
Edema ratio
0.51
LV-mass
0.02
LV-EF
0.21
LV-EDV
0.13
LV-ESV
0.09
3T
Native T1
61.41
1.13 (1.01-1.21)
0.001
96 (85-100)
95 (86-97)
Chi-Square=61.41, p<0.001; Wald=11.1; -2 Log likelihood=27.5, Nagelkerke R2=0.82.
Variables not in equation
Postcontrast T1
/
0.22
LGE (present)
0.66
Increased T2
0.19
signal (present)
LV-mass
/
0.24
LV-EF
/
0.68
LV-EDV
/
0.74
LV-ESV
/
0.66
95 (85-98)