Rapid Fire Session

Session: Rapid Fire Session 3: Tissue Characterization, Strain, Machine Learning, Pediatric and Congenital Heart Disease (Monitor 5)

Comparison of COVID-19 Vaccine Associated Myocarditis and Non-COVID Viral Myocarditis – Preliminary Findings from the MYCOVACC Cardiac MRI Substudy

Friday, February 6, 2026

10:43 AM - 10:50 AM

Location: Galapagos / Aruba / Ilhabela (2nd Lower Level)

Presenting Author(s)

LS

Lorena Squassante Capeline, MD, PhD

Postdoctoral Fellow
University of Calgary
Calgary, Alberta, Canada

Primary Author(s)

LS

Lorena Squassante Capeline, MD, PhD

Postdoctoral Fellow
University of Calgary
Calgary, Alberta, Canada

Co-Author(s)

RM

Rylan Marianchuk, BSc

Masters Student
University of Calgary
Calgary, Alberta, Canada
Dina Labib, MD, PhD, FSCMR

Associate Scientific Director, Personalized Diagnostics Program; Adjunct Assistant Professor
University of Calgary
Calgary, Alberta, Canada
Justin J. Tse, PhD, MSc, BSc

Research Associate
University of Calgary
Calgary, Alberta, Canada
TB

Talia A. Beckie, BEng

Cardiac Imaging Systems Engineer
Libin cardiovascular Institute, University of Calgary
Calgary, Alberta, Canada
KH

Kinnon Haufe, BSc

Core Lab Analyst
University of Calgary, Canada
CJ

Cory R. Jensen, BSc

Cardiac Machine Learning Developer
Libin Cardiovascular Institute, University of Calgary, Canada
OE

Omar El Ferri

MD Student
University of Calgary, Canada
SR

Sandra Rivest, RN

Research Coordinator
Libin Cardiovascular Institute; University of Calgary
Calgary, Alberta, Canada
JF

Jacqueline Flewitt, MSc

Manager of Strategic Partnerships
Libin Cardiovascular Institute; University of Calgary
Calgary, Alberta, Canada
YF

Yuanchao Feng, PhD

Senior AHS analyst
Libin Cardiovascular Institute; University of Calgary
Calgary, Alberta, Canada
MM

Michael McDonald, MD

Associate Professor
University of Toronto, Canada
MK

Melanie King, PhD

Director, Program Development and Implementation
Libin Cardiovascular Institute, University of Calgary, Canada
MW

Meredith Wright, PhD

Member of the MYCOVACC Study Team / Senior Project Advisor
Canadian Cardiovascular Society, Canada
NH

Nathaniel Hawkins, MD

Professor
University of British Columbia, British Columbia, Canada
KH

Kate Hanneman, MD, MPH

Radiologist
Toronto General Hospital
Toronto, Ontario, Canada
James A. White, MD

Professor
Libin Cardiovascular Institute; University of Calgary
Calgary, Alberta, Canada

Background: COVID-19 mRNA vaccination associated (VAM) is a rare adverse event that has raised global interests in establishing a deep characterization of its phenotype and natural history relative to the more commonly encountered community-acquired (non-COVID) myocarditis (CAM). The MYCOVACC CMR substudy is a pan-Canadian study investigating baseline and convalescent CMR phenotyping of VAM with comparison to historical non-COVID CAM cohorts pre-dating vaccination programs.

Methods: The currently analyzed cohort included 43 patients with VAM and 286 with CAM confirmed by Modified Lake Louise Criteria on CMR imaging performed within 60 days of symptom onset. 100 healthy volunteers (HV) were recruited to establish healthy reference values for all investigated markers. CMR imaging was inclusive of routine cine and LGE imaging, T1 (MOLLI) and T2 mapping. Core laboratory analysis was performed using commercial software (cvi42) in addition to 4Deep phenomics analysis, an automated 4D mesh modelling tool, to assess LV 3D principal strain and regional wall thickness markers. Patient groups were compared using Kruskal-Wallis test. Associations of VAM vs CAM group membership with CMR markers were assessed in multivariable models, adjusting for age, sex, and duration of symptom onset. Patients were followed for a composite outcome of all-cause mortality, heart failure admission, sustained ventricular arrhythmia, or complete heart block.

Results: Overall, the combined study cohort was predominantly male (n = 284; 66.2%) with the VAM group having higher male prominence and being significantly younger (median age 25 years, p < 0.001). Versus HV, both patient groups showed reductions in left ventricular ejection fraction (LVEF), increased LV mass, and reduced 3D maximum principal strain (3D maxPS; Table 1). Adjusting for age, sex, and duration from symptom onset, no significant differences in global function (LVEF or 3D maxPS), LV mass, or LGE fibrosis burden was observed between VAM and CAM. Using segmental analysis, worse 3D maxPS was observed in the mid inferolateral segment (mean difference 13.9%, p = 0.01) with greater LGE burden in the basal to mid inferolateral segments (p < 0.001 and p = 0.007) in VAM vs CAM (Figure 1). End-diastolic 4Deep models for representative patients from each group are shown in Figure 2. Over a median follow-up of 3.3 years and 6.8 years, respectively, clinical outcomes did not differ between the VAM and CAM groups (2% vs. 9%, p = 0.22).

Conclusion: VAM and CAM share similar baseline phenotypic characteristics with respect to global myocardial injury markers with clinical outcomes being exceptionally rare in the VAM group. Our preliminary findings suggest the potential for regionally increased inflammatory injury using regional analysis with greater LGE burden and reduced 3D maxPS in the inferolateral segments. Ongoing analyses of a larger, pan-Canadian cohort inclusive of tissue mapping and repeat convalescent CMR is planned.

Baseline characteristics of the study cohort, stratified by health volunteers, vaccine-associate myocarditis and non-COVID viral myocarditis.

Characteristics	HV N = 100 (23%)¹	VAM N = 43 (10%)¹	NCM N = 286 (67%)¹	p-value²	β coefficient³ (95%CI)	β p-value
Age, yrs	46.0 (30.0, 54.0)	25.0 (21.0, 35.0)	41.5 (30.0, 57.0)	< 0.001
Male sex	46 (46%)	36 (84%)	202 (71%)	< 0.001
Hypertension	-	6 (14%)	80 (28%)	0.062
Diabetes	-	6 (14%)	40 (14%)	>0.99
Hyperlipidemia	-	14 (33%)	158 (56%)	0.005
Atrial fibrillation/flutter	-	1 (2%)	8 (3%)	>0.99
eGFR	-	136.9 (116.2, 143.4)	127.5 (109.2, 143.3)	0.20
CKD	-	1 (2%)	1 (0%)	0.25
Outcome	-	1 (2%)	25 (9%)	0.22
Follow-up, yrs	-	3.3 (3.0, 3.4)	6.8 (5.5, 8.0)	< 0.001

CMR characteristics
LVEDVI, mL/m²	81.0 (71.5, 90.0)	85.3 (73.6, 90.6)	80.3 (68.7, 90.7)	0.38	3.381 (-3.26, 10.02)	0.32
LVESVI, mL/m²	29.0 (25.0, 35.5)	34.9 (30.9, 42.9)	34.0 (27.6, 43.8)	< 0.001	4.522 (-1.394, 10.44)	0.13
LVEF, %	63.0 (61.0, 67.0)	57.6 (51.7, 61.0)	57.1 (49.5, 61.6)	< 0.001	-1.442 (-4.798, 1.915)	0.40
LVMI, g/m²	46.4 (41.0, 55.6)	53.8 (48.3, 62.3)	57.9 (49.9, 66.4)	< 0.001	-4.132 (-8.457, 0.1922)	0.061
RVEDVI, mL/m²	89.5 (77.8, 99.6)	85.5 (77.4, 97.9)	82.4 (68.9, 96.2)	0.008	0.7803 (-4.779, 6.34)	0.78
RVESVI, mL/m²	37.5 (32.4, 45.1)	42.9 (33.3, 45.5)	37.4 (29.8, 46.1)	0.25	2.805 (-1.522, 7.132)	0.20
RVEF, %	57.0 (53.5, 62.0)	53.4 (49.9, 56.1)	54.7 (49.6, 58.9)	< 0.001	-1.665 (-4.304, 0.9746)	0.22
LAVI, mL/m²	35.0 (31.1, 42.5)	30.9 (27.8, 38.7)	31.4 (25.1, 38.9)	< 0.001	2.71 (-1.224, 6.643)	0.18
LGE, % fibrosis/scar	-	10.3 (5.9, 19.1)	5.9 (2.9, 10.3)	0.002	2.717 (-0.2207, 5.654)	0.070

4Deep global markers
4D LVEDVI, mL/m²	100.3 (87.3, 112.9)	109.0 (93.5, 122.3)	102.6 (84.2, 122.5)	0.26	3.41 (-6.899, 13.72)	0.52
4D LVESVI, mL/m²	41.1 (34.5, 48.6)	50.7 (40.4, 56.9)	49.1 (38.2, 65.5)	< 0.001	2.963 (-7.095, 13.02)	0.56
4D LVEF, %	59.6 (55.9, 62.6)	53.5 (45.6, 59.3)	52.3 (44.1, 58.7)	< 0.001	0.9896 (-4.384, 6.363)	0.72
4D max PS, %	67.2 (59.2, 78.4)	51.8 (48.3, 66.7)	55.5 (43.7, 72.3)	< 0.001	1.085 (-7.876, 10.05)	0.81
4D min PS, %	-22.8 (-24.6, -20.6)	-20.8 (-23.1, -18.8)	-20.4 (-22.5, -17.6)	< 0.001	-0.7558 (-2.404, 0.8928)	0.37
4D LVMI, g/m²	47.0 (41.2, 54.8)	55.7 (50.5, 61.0)	56.5 (48.2, 63.7)	< 0.001	-1.672 (-5.693, 2.349)	0.41
4D WT LVED, mm	11.0 (9.8, 13.1)	12.5 (11.4, 13.5)	12.8 (11.3, 14.6)	< 0.001	-0.2252 (-1.079, 0.6285)	0.60

¹ Values are median (Q1, Q3), or counts (%)

² Kruskal-Wallis rank sum test; Pearson’s Chi-squared test; Fisher’s exact test

³ Beta coefficient for vaccine-associate myocarditis vs non-COVID viral myocarditis, adjusting for age, sex and inpatient/outpatient status

CMR indicates cardiac magnetic resonance; CKD, chronic kidney disease; eGFR, estimated glomerular filtration rate; LAVI, left atrium volume indexed to body surface area; LGE, late gadolinium enhancement; LVEDVI, left ventricular end-diastolic volume indexed to body surface area; LVEF, left ventricular ejection fraction; LVESVI, left ventricular end-systolic volume indexed to body surface area; LVMI, left ventricular mass index; max PS, maximum principal strain; min PS, minimum principal strain; RVEDVI, right ventricular end-diastolic volume indexed to body surface area; RVEF, right ventricular ejection fraction; RVESVI, right ventricular end-systolic volume indexed to body surface area; WT, wall thickness.

Baseline characteristics of the study cohort

Characteristics	HV N = 100	CAM N = 286	VAM N = 43	p-value¹	β coefficient² (95%CI)	β p-value
Age, yrs	46.0 (30.0, 54.0)	41.5 (30.0, 57.0)	25.0 (21.0, 35.0)	< 0.001
Male sex	46 (46%)	202 (71%)	36 (84%)	< 0.001
Hypertension	-	80 (28%)	6 (14%)	0.062
Diabetes	-	40 (14%)	6 (14%)	>0.99
Hyperlipidemia	-	158 (56%)	14 (33%)	0.005
Atrial fibrillation/flutter	-	8 (3%)	1 (2%)	>0.99
eGFR	-	127.5 (109.2, 143.3)	136.9 (116.2, 143.4)	0.20
CKD	-	1 (0%)	1 (2%)	0.25
Composite outcome	-	25 (9%)	1 (2%)	0.22

Conventional CMR characteristics
LVEDVI, mL/m²	81.0 (71.5, 90.0)	80.3 (68.7, 90.7)	85.3 (73.6, 90.6)	0.38	3.381 (-3.26, 10.02)	0.32
LVESVI, mL/m²	29.0 (25.0, 35.5)	34.0 (27.6, 43.8)	34.9 (30.9, 42.9)	< 0.001	4.522 (-1.394, 10.44)	0.13
LVEF, %	63.0 (61.0, 67.0)	57.1 (49.5, 61.6)	57.6 (51.7, 61.0)	< 0.001	-1.442 (-4.798, 1.915)	0.40
LVMI, g/m²	46.4 (41.0, 55.6)	57.9 (49.9, 66.4)	53.8 (48.3, 62.3)	< 0.001	-4.132 (-8.457, 0.1922)	0.061
RVEDVI, mL/m²	89.5 (77.8, 99.6)	82.4 (68.9, 96.2)	85.5 (77.4, 97.9)	0.008	0.7803 (-4.779, 6.34)	0.78
RVESVI, mL/m²	37.5 (32.4, 45.1)	37.4 (29.8, 46.1)	42.9 (33.3, 45.5)	0.25	2.805 (-1.522, 7.132)	0.20
RVEF, %	57.0 (53.5, 62.0)	54.7 (49.6, 58.9)	53.4 (49.9, 56.1)	< 0.001	-1.665 (-4.304, 0.9746)	0.22
LAVI, mL/m²	35.0 (31.1, 42.5)	31.4 (25.1, 38.9)	30.9 (27.8, 38.7)	< 0.001	2.71 (-1.224, 6.643)	0.18
LGE, % fibrosis/scar	-	5.9 (2.9, 10.3)	10.3 (5.9, 19.1)	0.002	2.717 (-0.2207, 5.654)	0.070

4Deep global markers
LVEDVI, mL/m²	100.3 (87.3, 112.9)	102.6 (84.2, 122.5)	109.0 (93.5, 122.3)	0.26	3.41 (-6.899, 13.72)	0.52
LVESVI, mL/m²	41.1 (34.5, 48.6)	49.1 (38.2, 65.5)	50.7 (40.4, 56.9)	< 0.001	2.963 (-7.095, 13.02)	0.56
LVEF, %	59.6 (55.9, 62.6)	52.3 (44.1, 58.7)	53.5 (45.6, 59.3)	< 0.001	0.9896 (-4.384, 6.363)	0.72
3D max PS, %	67.2 (59.2, 78.4)	55.5 (43.7, 72.3)	51.8 (48.3, 66.7)	< 0.001	1.085 (-7.876, 10.05)	0.81
3D min PS, %	-22.8 (-24.6, -20.6)	-20.4 (-22.5, -17.6)	-20.8 (-23.1, -18.8)	< 0.001	-0.7558 (-2.404, 0.8928)	0.37
3D LVMI, g/m²	47.0 (41.2, 54.8)	56.5 (48.2, 63.7)	55.7 (50.5, 61.0)	< 0.001	-1.672 (-5.693, 2.349)	0.41
3D max wall thick, mm	11.0 (9.8, 13.1)	12.8 (11.3, 14.6)	12.5 (11.4, 13.5)	< 0.001	-0.2252 (-1.079, 0.6285)	0.60

Values are median (Q1, Q3), or counts (%)

¹ Kruskal-Wallis rank sum test; Pearson’s Chi-squared test; Fisher’s exact test

² Beta coefficient for association of vaccine-associate myocarditis vs non-COVID viral myocarditis with each CMR marker, adjusting for age, sex and duration from symptom onset

CMR indicates cardiac magnetic resonance; CKD, chronic kidney disease; eGFR, estimated glomerular filtration rate; LAVI, left atrium volume indexed to body surface area; LGE, late gadolinium enhancement; LVEDVI, left ventricular end-diastolic volume indexed to body surface area; LVEF, left ventricular ejection fraction; LVESVI, left ventricular end-systolic volume indexed to body surface area; LVMI, left ventricular mass index; max PS, maximum principal strain; min PS, minimum principal strain; RVEDVI, right ventricular end-diastolic volume indexed to body surface area; RVEF, right ventricular ejection fraction; RVESVI, right ventricular end-systolic volume indexed to body surface area.

AHA segmental distribution of median values for LV mass, LGE fibrosis burden, and principal strain.
End-diastolic 3D meshes for a representative participant from each of the healthy volunteer, Covid-19 vaccine myocarditis, and non-Covid-19 viral myocarditis.