Table 1 Open in new tab Baseline...

	P-VA (n = 32)	M-VA (n = 42)	P	Total VM (n = 74)	Comparator VNM (n = 74)	P
Clinical profile
Age (years)	46 ± 16	47 ± 15	0.783	47 ± 16	47 ± 15	1.000
Male sex	19 (59)	30 (71)	0.326	49 (66)	48 (65)	1.000
Caucasian	27 (84)	39 (93)	0.280	66 (89)	68 (92)	0.780
Associated SR/HDs	4 (13)	5 (12)	1.000	9 (12)	11 (15)	0.811
History of SCD/CMP	1 (3)	3 (7)	1.000	4 (5)	3 (4)	1.000
Presentation
Chest pain	12 (38)	15 (36)	1.000	27 (36)	26 (35)	1.000
Dyspnoea	12 (38)	9 (21)	0.193	21 (28)	21 (28)	1.000
Syncope/palpitation	8 (25)	18 (43)	0.143	26 (35)	27 (36)	1.000
Complicated^a	16 (50)	17 (40)	0.483	33 (45)	33 (45)	1.000
Fever in the last 30 days	16 (50)	6 (14)	0.002	22 (30)	4 (5)	<0.001
VA documented by 24 h of admission
VF	6 (19)	0 (0)	0.005	6 (8)	1 (1)	0.116
Sustained VT	5 (16)	9 (21)	0.566	14 (19)	20 (27)	0.329
NSVT	10 (31)	19 (45)	0.241	29 (39)	31 (42)	0.867
Lown’s grade ≥ 2^a VEBs	11 (43)	14 (33)	1.000	25 (34)	27 (36)	0.863
VEB daily burden (10³)	1.2 (0.4–3.1)	1.0 (0.3–3.6)	0.695	1.1 (0.3–3.4)	1.3 (0.4–3.8)	0.761
Baseline ECG and other arrhythmias
PQ (ms)	173 ± 40	179 ± 38	0.513	175 ± 39	179 ± 41	0.544
QRS duration (ms)	102 ± 22	104 ± 21	0.913	103 ± 21	105 ± 23	0.582
QTc (ms)	416 ± 34	409 ± 32	0.425	411 ± 32	409 ± 33	0.709
LBBB	2 (6)	3 (7)	1.000	5 (7)	6 (8)	1.000
AF	1 (3)	2 (5)	1.000	3 (4)	4 (5)	1.000
Blood exams
T-troponin (ng/L)	46 (16–314)	38 (9–255)	0.734	41 (13–286)	35 (10–268)	0.813
NT-proBNP (pg/mL)	429 (123–1812)	348 (100–1399)	0.624	399 (106–1545)	313 (101–1499)	0.792
C-reactive protein (mg/L)	12 (6–23)	5 (3–16)	0.026	7 (4–19)	5 (3–17)	0.566
ESR (mm/h)	13 (6–26)	11 (5–24)	0.711	12 (5–26)	10 (5–24)	0.723
Echocardiogram
LVEDVi (mL/m²)	64 ± 22	67 ± 20	0.542	66 ± 21	68 ± 22	0.573
LVEF (%)	46 ± 14	55 ± 12	0.004	51 ± 13	51 ± 13	1.000
LVEF < 50%	12 (38)	10 (24)	0.305	22 (30)	22 (30)	1.000
E/E′	9 ± 4	8 ± 4	0.290	8 ± 4	8 ± 3	1.000
TAPSE (mm)	21 ± 4	22 ± 3	0.223	22 ± 4	22 ± 4	1.000
Pericardial effusion	3 (9)	6 (14)	0.723	9 (12)	11 (15)	0.811
Cardiac magnetic resonance
Updated LLC+	31 (97)	34 (81)	0.069	65 (88)	59 (79)	0.265
T₂-STIR+	23 (72)	23 (55)	0.154	46 (62)	40 (54)	0.405
LGE+	31 (97)	42 (100)	1.000	73 (99)	74 (100)	1.000
Septal LGE	13 (41)	19 (45)	0.814	32 (43)	34 (46)	0.869
T₂ > 50 ms	18/20 (90)	20/24 (83)	0.673	38/44 (86)	33/41 (80)	0.564
Native T₁ > 1045 ms	19/20 (95)	21/24 (88)	0.614	40/44 (91)	37/41 (90)	1.000
ECV > 27%	16/20 (80)	20/24 (83)	1.000	36/44 (82)	35/41 (85)	0.386
Endomyocardial biopsy
Lymphocytic histotype	32 (100)	42 (100)	1.000	74 (100)	74 (100)	1.000
CD3⁺ > 7/mm²	32 (100)	42 (100)	1.000	74 (100)	74 (100)	1.000
Necrosis	24 (75)	22 (52)	0.056	46 (62)	38 (51)	0.245
Replacement fibrosis	8 (25)	30 (71)	<0.001	38 (51)	56 (72)	0.004
Myocyte hypertrophy	5 (16)	15 (36)	0.067	20 (27)	28 (38)	0.219
Viral genomes	32 (100)	42 (100)	1.000	74 (100)	0 (0)	<0.001

P-VA (n = 32)

M-VA (n = 42)

Total VM (n = 74)

Comparator VNM (n = 74)

Clinical profile

Age (years)

46 ± 16

47 ± 15

0.783

47 ± 16

47 ± 15

1.000

Male sex

19 (59)

30 (71)

0.326

49 (66)

48 (65)

1.000

Caucasian

27 (84)

39 (93)

0.280

66 (89)

68 (92)

0.780

Associated SR/HDs

4 (13)

5 (12)

1.000

9 (12)

11 (15)

0.811

History of SCD/CMP

1 (3)

3 (7)

1.000

4 (5)

3 (4)

1.000

Presentation

Chest pain

12 (38)

15 (36)

1.000

27 (36)

26 (35)

1.000

Dyspnoea

12 (38)

9 (21)

0.193

21 (28)

1.000

Syncope/palpitation

8 (25)

18 (43)

0.143

26 (35)

27 (36)

1.000

Complicated^a

16 (50)

17 (40)

0.483

33 (45)

1.000

Fever in the last 30 days

16 (50)

6 (14)

0.002

22 (30)

4 (5)

<0.001

VA documented by 24 h of admission

6 (19)

0 (0)

0.005

6 (8)

1 (1)

0.116

Sustained VT

5 (16)

9 (21)

0.566

14 (19)

20 (27)

0.329

NSVT

10 (31)

19 (45)

0.241

29 (39)

31 (42)

0.867

Lown’s grade ≥ 2^a VEBs

11 (43)

14 (33)

1.000

25 (34)

27 (36)

0.863

VEB daily burden (10³)

1.2 (0.4–3.1)

1.0 (0.3–3.6)

0.695

1.1 (0.3–3.4)

1.3 (0.4–3.8)

0.761

Baseline ECG and other arrhythmias

PQ (ms)

173 ± 40

179 ± 38

0.513

175 ± 39

179 ± 41

0.544

QRS duration (ms)

102 ± 22

104 ± 21

0.913

103 ± 21

105 ± 23

0.582

QTc (ms)

416 ± 34

409 ± 32

0.425

411 ± 32

409 ± 33

0.709

LBBB

2 (6)

3 (7)

1.000

5 (7)

6 (8)

1.000

1 (3)

2 (5)

1.000

3 (4)

4 (5)

1.000

Blood exams

T-troponin (ng/L)

46 (16–314)

38 (9–255)

0.734

41 (13–286)

35 (10–268)

0.813

NT-proBNP (pg/mL)

429 (123–1812)

348 (100–1399)

0.624

399 (106–1545)

313 (101–1499)

0.792

C-reactive protein (mg/L)

12 (6–23)

5 (3–16)

0.026

7 (4–19)

5 (3–17)

0.566

ESR (mm/h)

13 (6–26)

11 (5–24)

0.711

12 (5–26)

10 (5–24)

0.723

Echocardiogram

LVEDVi (mL/m²)

64 ± 22

67 ± 20

0.542

66 ± 21

68 ± 22

0.573

LVEF (%)

46 ± 14

55 ± 12

0.004

51 ± 13

1.000

LVEF < 50%

12 (38)

10 (24)

0.305

22 (30)

1.000

E/E′

9 ± 4

8 ± 4

0.290

8 ± 4

8 ± 3

1.000

TAPSE (mm)

21 ± 4

22 ± 3

0.223

22 ± 4

1.000

Pericardial effusion

3 (9)

6 (14)

0.723

9 (12)

11 (15)

0.811

Cardiac magnetic resonance

Updated LLC+

31 (97)

34 (81)

0.069

65 (88)

59 (79)

0.265

T₂-STIR+

23 (72)

23 (55)

0.154

46 (62)

40 (54)

0.405

LGE+

31 (97)

42 (100)

1.000

73 (99)

74 (100)

1.000

Septal LGE

13 (41)

19 (45)

0.814

32 (43)

34 (46)

0.869

T₂ > 50 ms

18/20 (90)

20/24 (83)

0.673

38/44 (86)

33/41 (80)

0.564

Native T₁ > 1045 ms

19/20 (95)

21/24 (88)

0.614

40/44 (91)

37/41 (90)

1.000

ECV > 27%

16/20 (80)

20/24 (83)

1.000

36/44 (82)

35/41 (85)

0.386

Endomyocardial biopsy

Lymphocytic histotype

32 (100)

42 (100)

1.000

74 (100)

1.000

CD3⁺ > 7/mm²

32 (100)

42 (100)

1.000

74 (100)

1.000

Necrosis

24 (75)

22 (52)

0.056

46 (62)

38 (51)

0.245

Replacement fibrosis

8 (25)

30 (71)

<0.001

38 (51)

56 (72)

0.004

Myocyte hypertrophy

5 (16)

15 (36)

0.067

20 (27)

28 (38)

0.219

Viral genomes

32 (100)

42 (100)

1.000

74 (100)

0 (0)

<0.001

	P-VA (n = 32)	M-VA (n = 42)	P	Total VM (n = 74)	Comparator VNM (n = 74)	P
Clinical profile
Age (years)	46 ± 16	47 ± 15	0.783	47 ± 16	47 ± 15	1.000
Male sex	19 (59)	30 (71)	0.326	49 (66)	48 (65)	1.000
Caucasian	27 (84)	39 (93)	0.280	66 (89)	68 (92)	0.780
Associated SR/HDs	4 (13)	5 (12)	1.000	9 (12)	11 (15)	0.811
History of SCD/CMP	1 (3)	3 (7)	1.000	4 (5)	3 (4)	1.000
Presentation
Chest pain	12 (38)	15 (36)	1.000	27 (36)	26 (35)	1.000
Dyspnoea	12 (38)	9 (21)	0.193	21 (28)	21 (28)	1.000
Syncope/palpitation	8 (25)	18 (43)	0.143	26 (35)	27 (36)	1.000
Complicated^a	16 (50)	17 (40)	0.483	33 (45)	33 (45)	1.000
Fever in the last 30 days	16 (50)	6 (14)	0.002	22 (30)	4 (5)	<0.001
VA documented by 24 h of admission
VF	6 (19)	0 (0)	0.005	6 (8)	1 (1)	0.116
Sustained VT	5 (16)	9 (21)	0.566	14 (19)	20 (27)	0.329
NSVT	10 (31)	19 (45)	0.241	29 (39)	31 (42)	0.867
Lown’s grade ≥ 2^a VEBs	11 (43)	14 (33)	1.000	25 (34)	27 (36)	0.863
VEB daily burden (10³)	1.2 (0.4–3.1)	1.0 (0.3–3.6)	0.695	1.1 (0.3–3.4)	1.3 (0.4–3.8)	0.761
Baseline ECG and other arrhythmias
PQ (ms)	173 ± 40	179 ± 38	0.513	175 ± 39	179 ± 41	0.544
QRS duration (ms)	102 ± 22	104 ± 21	0.913	103 ± 21	105 ± 23	0.582
QTc (ms)	416 ± 34	409 ± 32	0.425	411 ± 32	409 ± 33	0.709
LBBB	2 (6)	3 (7)	1.000	5 (7)	6 (8)	1.000
AF	1 (3)	2 (5)	1.000	3 (4)	4 (5)	1.000
Blood exams
T-troponin (ng/L)	46 (16–314)	38 (9–255)	0.734	41 (13–286)	35 (10–268)	0.813
NT-proBNP (pg/mL)	429 (123–1812)	348 (100–1399)	0.624	399 (106–1545)	313 (101–1499)	0.792
C-reactive protein (mg/L)	12 (6–23)	5 (3–16)	0.026	7 (4–19)	5 (3–17)	0.566
ESR (mm/h)	13 (6–26)	11 (5–24)	0.711	12 (5–26)	10 (5–24)	0.723
Echocardiogram
LVEDVi (mL/m²)	64 ± 22	67 ± 20	0.542	66 ± 21	68 ± 22	0.573
LVEF (%)	46 ± 14	55 ± 12	0.004	51 ± 13	51 ± 13	1.000
LVEF < 50%	12 (38)	10 (24)	0.305	22 (30)	22 (30)	1.000
E/E′	9 ± 4	8 ± 4	0.290	8 ± 4	8 ± 3	1.000
TAPSE (mm)	21 ± 4	22 ± 3	0.223	22 ± 4	22 ± 4	1.000
Pericardial effusion	3 (9)	6 (14)	0.723	9 (12)	11 (15)	0.811
Cardiac magnetic resonance
Updated LLC+	31 (97)	34 (81)	0.069	65 (88)	59 (79)	0.265
T₂-STIR+	23 (72)	23 (55)	0.154	46 (62)	40 (54)	0.405
LGE+	31 (97)	42 (100)	1.000	73 (99)	74 (100)	1.000
Septal LGE	13 (41)	19 (45)	0.814	32 (43)	34 (46)	0.869
T₂ > 50 ms	18/20 (90)	20/24 (83)	0.673	38/44 (86)	33/41 (80)	0.564
Native T₁ > 1045 ms	19/20 (95)	21/24 (88)	0.614	40/44 (91)	37/41 (90)	1.000
ECV > 27%	16/20 (80)	20/24 (83)	1.000	36/44 (82)	35/41 (85)	0.386
Endomyocardial biopsy
Lymphocytic histotype	32 (100)	42 (100)	1.000	74 (100)	74 (100)	1.000
CD3⁺ > 7/mm²	32 (100)	42 (100)	1.000	74 (100)	74 (100)	1.000
Necrosis	24 (75)	22 (52)	0.056	46 (62)	38 (51)	0.245
Replacement fibrosis	8 (25)	30 (71)	<0.001	38 (51)	56 (72)	0.004
Myocyte hypertrophy	5 (16)	15 (36)	0.067	20 (27)	28 (38)	0.219
Viral genomes	32 (100)	42 (100)	1.000	74 (100)	0 (0)	<0.001

P-VA (n = 32)

M-VA (n = 42)

Total VM (n = 74)

Comparator VNM (n = 74)

Clinical profile

Age (years)

46 ± 16

47 ± 15

0.783

47 ± 16

47 ± 15

1.000

Male sex

19 (59)

30 (71)

0.326

49 (66)

48 (65)

1.000

Caucasian

27 (84)

39 (93)

0.280

66 (89)

68 (92)

0.780

Associated SR/HDs

4 (13)

5 (12)

1.000

9 (12)

11 (15)

0.811

History of SCD/CMP

1 (3)

3 (7)

1.000

4 (5)

3 (4)

1.000

Presentation

Chest pain

12 (38)

15 (36)

1.000

27 (36)

26 (35)

1.000

Dyspnoea

12 (38)

9 (21)

0.193

21 (28)

1.000

Syncope/palpitation

8 (25)

18 (43)

0.143

26 (35)

27 (36)

1.000

Complicated^a

16 (50)

17 (40)

0.483

33 (45)

1.000

Fever in the last 30 days

16 (50)

6 (14)

0.002

22 (30)

4 (5)

<0.001

VA documented by 24 h of admission

6 (19)

0 (0)

0.005

6 (8)

1 (1)

0.116

Sustained VT

5 (16)

9 (21)

0.566

14 (19)

20 (27)

0.329

NSVT

10 (31)

19 (45)

0.241

29 (39)

31 (42)

0.867

Lown’s grade ≥ 2^a VEBs

11 (43)

14 (33)

1.000

25 (34)

27 (36)

0.863

VEB daily burden (10³)

1.2 (0.4–3.1)

1.0 (0.3–3.6)

0.695

1.1 (0.3–3.4)

1.3 (0.4–3.8)

0.761

Baseline ECG and other arrhythmias

PQ (ms)

173 ± 40

179 ± 38

0.513

175 ± 39

179 ± 41

0.544

QRS duration (ms)

102 ± 22

104 ± 21

0.913

103 ± 21

105 ± 23

0.582

QTc (ms)

416 ± 34

409 ± 32

0.425

411 ± 32

409 ± 33

0.709

LBBB

2 (6)

3 (7)

1.000

5 (7)

6 (8)

1.000

1 (3)

2 (5)

1.000

3 (4)

4 (5)

1.000

Blood exams

T-troponin (ng/L)

46 (16–314)

38 (9–255)

0.734

41 (13–286)

35 (10–268)

0.813

NT-proBNP (pg/mL)

429 (123–1812)

348 (100–1399)

0.624

399 (106–1545)

313 (101–1499)

0.792

C-reactive protein (mg/L)

12 (6–23)

5 (3–16)

0.026

7 (4–19)

5 (3–17)

0.566

ESR (mm/h)

13 (6–26)

11 (5–24)

0.711

12 (5–26)

10 (5–24)

0.723

Echocardiogram

LVEDVi (mL/m²)

64 ± 22

67 ± 20

0.542

66 ± 21

68 ± 22

0.573

LVEF (%)

46 ± 14

55 ± 12

0.004

51 ± 13

1.000

LVEF < 50%

12 (38)

10 (24)

0.305

22 (30)

1.000

E/E′

9 ± 4

8 ± 4

0.290

8 ± 4

8 ± 3

1.000

TAPSE (mm)

21 ± 4

22 ± 3

0.223

22 ± 4

1.000

Pericardial effusion

3 (9)

6 (14)

0.723

9 (12)

11 (15)

0.811

Cardiac magnetic resonance

Updated LLC+

31 (97)

34 (81)

0.069

65 (88)

59 (79)

0.265

T₂-STIR+

23 (72)

23 (55)

0.154

46 (62)

40 (54)

0.405

LGE+

31 (97)

42 (100)

1.000

73 (99)

74 (100)

1.000

Septal LGE

13 (41)

19 (45)

0.814

32 (43)

34 (46)

0.869

T₂ > 50 ms

18/20 (90)

20/24 (83)

0.673

38/44 (86)

33/41 (80)

0.564

Native T₁ > 1045 ms

19/20 (95)

21/24 (88)

0.614

40/44 (91)

37/41 (90)

1.000

ECV > 27%

16/20 (80)

20/24 (83)

1.000

36/44 (82)

35/41 (85)

0.386

Endomyocardial biopsy

Lymphocytic histotype

32 (100)

42 (100)

1.000

74 (100)

1.000

CD3⁺ > 7/mm²

32 (100)

42 (100)

1.000

74 (100)

1.000

Necrosis

24 (75)

22 (52)

0.056

46 (62)

38 (51)

0.245

Replacement fibrosis

8 (25)

30 (71)

<0.001

38 (51)

56 (72)

0.004

Myocyte hypertrophy

5 (16)

15 (36)

0.067

20 (27)

28 (38)

0.219

Viral genomes

32 (100)

42 (100)

1.000

74 (100)

0 (0)

<0.001

Table 1

Open in new tab

Baseline features of patients with viral myocarditis and polymorphic vs. monomorphic ventricular arrhythmias

	P-VA (n = 32)	M-VA (n = 42)	P	Total VM (n = 74)	Comparator VNM (n = 74)	P
Clinical profile
Age (years)	46 ± 16	47 ± 15	0.783	47 ± 16	47 ± 15	1.000
Male sex	19 (59)	30 (71)	0.326	49 (66)	48 (65)	1.000
Caucasian	27 (84)	39 (93)	0.280	66 (89)	68 (92)	0.780
Associated SR/HDs	4 (13)	5 (12)	1.000	9 (12)	11 (15)	0.811
History of SCD/CMP	1 (3)	3 (7)	1.000	4 (5)	3 (4)	1.000
Presentation
Chest pain	12 (38)	15 (36)	1.000	27 (36)	26 (35)	1.000
Dyspnoea	12 (38)	9 (21)	0.193	21 (28)	21 (28)	1.000
Syncope/palpitation	8 (25)	18 (43)	0.143	26 (35)	27 (36)	1.000
Complicated^a	16 (50)	17 (40)	0.483	33 (45)	33 (45)	1.000
Fever in the last 30 days	16 (50)	6 (14)	0.002	22 (30)	4 (5)	<0.001
VA documented by 24 h of admission
VF	6 (19)	0 (0)	0.005	6 (8)	1 (1)	0.116
Sustained VT	5 (16)	9 (21)	0.566	14 (19)	20 (27)	0.329
NSVT	10 (31)	19 (45)	0.241	29 (39)	31 (42)	0.867
Lown’s grade ≥ 2^a VEBs	11 (43)	14 (33)	1.000	25 (34)	27 (36)	0.863
VEB daily burden (10³)	1.2 (0.4–3.1)	1.0 (0.3–3.6)	0.695	1.1 (0.3–3.4)	1.3 (0.4–3.8)	0.761
Baseline ECG and other arrhythmias
PQ (ms)	173 ± 40	179 ± 38	0.513	175 ± 39	179 ± 41	0.544
QRS duration (ms)	102 ± 22	104 ± 21	0.913	103 ± 21	105 ± 23	0.582
QTc (ms)	416 ± 34	409 ± 32	0.425	411 ± 32	409 ± 33	0.709
LBBB	2 (6)	3 (7)	1.000	5 (7)	6 (8)	1.000
AF	1 (3)	2 (5)	1.000	3 (4)	4 (5)	1.000
Blood exams
T-troponin (ng/L)	46 (16–314)	38 (9–255)	0.734	41 (13–286)	35 (10–268)	0.813
NT-proBNP (pg/mL)	429 (123–1812)	348 (100–1399)	0.624	399 (106–1545)	313 (101–1499)	0.792
C-reactive protein (mg/L)	12 (6–23)	5 (3–16)	0.026	7 (4–19)	5 (3–17)	0.566
ESR (mm/h)	13 (6–26)	11 (5–24)	0.711	12 (5–26)	10 (5–24)	0.723
Echocardiogram
LVEDVi (mL/m²)	64 ± 22	67 ± 20	0.542	66 ± 21	68 ± 22	0.573
LVEF (%)	46 ± 14	55 ± 12	0.004	51 ± 13	51 ± 13	1.000
LVEF < 50%	12 (38)	10 (24)	0.305	22 (30)	22 (30)	1.000
E/E′	9 ± 4	8 ± 4	0.290	8 ± 4	8 ± 3	1.000
TAPSE (mm)	21 ± 4	22 ± 3	0.223	22 ± 4	22 ± 4	1.000
Pericardial effusion	3 (9)	6 (14)	0.723	9 (12)	11 (15)	0.811
Cardiac magnetic resonance
Updated LLC+	31 (97)	34 (81)	0.069	65 (88)	59 (79)	0.265
T₂-STIR+	23 (72)	23 (55)	0.154	46 (62)	40 (54)	0.405
LGE+	31 (97)	42 (100)	1.000	73 (99)	74 (100)	1.000
Septal LGE	13 (41)	19 (45)	0.814	32 (43)	34 (46)	0.869
T₂ > 50 ms	18/20 (90)	20/24 (83)	0.673	38/44 (86)	33/41 (80)	0.564
Native T₁ > 1045 ms	19/20 (95)	21/24 (88)	0.614	40/44 (91)	37/41 (90)	1.000
ECV > 27%	16/20 (80)	20/24 (83)	1.000	36/44 (82)	35/41 (85)	0.386
Endomyocardial biopsy
Lymphocytic histotype	32 (100)	42 (100)	1.000	74 (100)	74 (100)	1.000
CD3⁺ > 7/mm²	32 (100)	42 (100)	1.000	74 (100)	74 (100)	1.000
Necrosis	24 (75)	22 (52)	0.056	46 (62)	38 (51)	0.245
Replacement fibrosis	8 (25)	30 (71)	<0.001	38 (51)	56 (72)	0.004
Myocyte hypertrophy	5 (16)	15 (36)	0.067	20 (27)	28 (38)	0.219
Viral genomes	32 (100)	42 (100)	1.000	74 (100)	0 (0)	<0.001

	P-VA (n = 32)	M-VA (n = 42)	P	Total VM (n = 74)	Comparator VNM (n = 74)	P
Clinical profile
Age (years)	46 ± 16	47 ± 15	0.783	47 ± 16	47 ± 15	1.000
Male sex	19 (59)	30 (71)	0.326	49 (66)	48 (65)	1.000
Caucasian	27 (84)	39 (93)	0.280	66 (89)	68 (92)	0.780
Associated SR/HDs	4 (13)	5 (12)	1.000	9 (12)	11 (15)	0.811
History of SCD/CMP	1 (3)	3 (7)	1.000	4 (5)	3 (4)	1.000
Presentation
Chest pain	12 (38)	15 (36)	1.000	27 (36)	26 (35)	1.000
Dyspnoea	12 (38)	9 (21)	0.193	21 (28)	21 (28)	1.000
Syncope/palpitation	8 (25)	18 (43)	0.143	26 (35)	27 (36)	1.000
Complicated^a	16 (50)	17 (40)	0.483	33 (45)	33 (45)	1.000
Fever in the last 30 days	16 (50)	6 (14)	0.002	22 (30)	4 (5)	<0.001
VA documented by 24 h of admission
VF	6 (19)	0 (0)	0.005	6 (8)	1 (1)	0.116
Sustained VT	5 (16)	9 (21)	0.566	14 (19)	20 (27)	0.329
NSVT	10 (31)	19 (45)	0.241	29 (39)	31 (42)	0.867
Lown’s grade ≥ 2^a VEBs	11 (43)	14 (33)	1.000	25 (34)	27 (36)	0.863
VEB daily burden (10³)	1.2 (0.4–3.1)	1.0 (0.3–3.6)	0.695	1.1 (0.3–3.4)	1.3 (0.4–3.8)	0.761
Baseline ECG and other arrhythmias
PQ (ms)	173 ± 40	179 ± 38	0.513	175 ± 39	179 ± 41	0.544
QRS duration (ms)	102 ± 22	104 ± 21	0.913	103 ± 21	105 ± 23	0.582
QTc (ms)	416 ± 34	409 ± 32	0.425	411 ± 32	409 ± 33	0.709
LBBB	2 (6)	3 (7)	1.000	5 (7)	6 (8)	1.000
AF	1 (3)	2 (5)	1.000	3 (4)	4 (5)	1.000
Blood exams
T-troponin (ng/L)	46 (16–314)	38 (9–255)	0.734	41 (13–286)	35 (10–268)	0.813
NT-proBNP (pg/mL)	429 (123–1812)	348 (100–1399)	0.624	399 (106–1545)	313 (101–1499)	0.792
C-reactive protein (mg/L)	12 (6–23)	5 (3–16)	0.026	7 (4–19)	5 (3–17)	0.566
ESR (mm/h)	13 (6–26)	11 (5–24)	0.711	12 (5–26)	10 (5–24)	0.723
Echocardiogram
LVEDVi (mL/m²)	64 ± 22	67 ± 20	0.542	66 ± 21	68 ± 22	0.573
LVEF (%)	46 ± 14	55 ± 12	0.004	51 ± 13	51 ± 13	1.000
LVEF < 50%	12 (38)	10 (24)	0.305	22 (30)	22 (30)	1.000
E/E′	9 ± 4	8 ± 4	0.290	8 ± 4	8 ± 3	1.000
TAPSE (mm)	21 ± 4	22 ± 3	0.223	22 ± 4	22 ± 4	1.000
Pericardial effusion	3 (9)	6 (14)	0.723	9 (12)	11 (15)	0.811
Cardiac magnetic resonance
Updated LLC+	31 (97)	34 (81)	0.069	65 (88)	59 (79)	0.265
T₂-STIR+	23 (72)	23 (55)	0.154	46 (62)	40 (54)	0.405
LGE+	31 (97)	42 (100)	1.000	73 (99)	74 (100)	1.000
Septal LGE	13 (41)	19 (45)	0.814	32 (43)	34 (46)	0.869
T₂ > 50 ms	18/20 (90)	20/24 (83)	0.673	38/44 (86)	33/41 (80)	0.564
Native T₁ > 1045 ms	19/20 (95)	21/24 (88)	0.614	40/44 (91)	37/41 (90)	1.000
ECV > 27%	16/20 (80)	20/24 (83)	1.000	36/44 (82)	35/41 (85)	0.386
Endomyocardial biopsy
Lymphocytic histotype	32 (100)	42 (100)	1.000	74 (100)	74 (100)	1.000
CD3⁺ > 7/mm²	32 (100)	42 (100)	1.000	74 (100)	74 (100)	1.000
Necrosis	24 (75)	22 (52)	0.056	46 (62)	38 (51)	0.245
Replacement fibrosis	8 (25)	30 (71)	<0.001	38 (51)	56 (72)	0.004
Myocyte hypertrophy	5 (16)	15 (36)	0.067	20 (27)	28 (38)	0.219
Viral genomes	32 (100)	42 (100)	1.000	74 (100)	0 (0)	<0.001

Comparison is shown between VM with P-VA vs. M-VA, as well as between VM and comparator group of VNM. Measures are mean ± standard deviation, median (quartile 1–quartile 3), or count (%). Significant differences are enhanced in bold font.

AF, atrial fibrillation; CD, cluster of differentiation; ECV, extracellular volume; ESR, erythrocyte sedimentation rate; LBBB, left bundle branch abnormality; LGE, late gadolinium enhancement; LLC, Lake Louise criteria; LVEDVi, left ventricular end-diastolic volume indexed; LVEF, left ventricular ejection fraction; M-VA, monomorphic ventricular arrhythmias; NSVT, non-sustained ventricular tachycardia; P-VA, polymorphic ventricular arrhythmias; SCD/CMP, sudden cardiac death/cardiomyopathy; SR/HDs, systemic rheumatologic/hematologic diseases; STIR, short-tau inversion recovery; TAPSE, tricuspid annular plane systolic excursion; VEBs, ventricular ectopic beats; VF, ventricular fibrillation; VM, viral myocarditis; VNM, virus-negative myocarditis; VT, ventricular tachycardia.

^aComplicated presentation included either acute heart failure, LVEF < 50%, or sustained VT/VF.⁸

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