Cardiac Magnetic Resonance Imaging Findings in Patients with and without Lyme Carditis: A Case-Control Study

Background: Lyme carditis (LC) is an uncommon but potentially fatal manifestation of early disseminated Lyme Disease, occurring in 1–10% of proven cases [1, 2]. While cardiac magnetic resonance imaging (CMR) is increasingly recognized for its diagnostic and prognostic utility in various etiologies of acute myocarditis, data on CMR findings in LC are limited [3]. Therefore, this case-control study aimed to characterize the CMR findings of patients with LC compared to viral myocarditis.

Methods: Consecutive patients presenting to two academic hospitals in Rhode Island, USA between years 2003–2024 with suspected LC and corresponding CMR studies were retrospectively identified. LC was suspected based on compatible clinical features (e.g., constitutional symptoms, heart block, recent tick exposure, erythema migrans rash), positive Lyme serology, and cardiac MRI findings consistent with myocarditis. Each case was matched 1:1 by age (±2 years) and sex to controls with presumed acute viral myocarditis, without positive Lyme serologies, who underwent CMR at the same institutions. The primary outcome was major adverse cardiovascular events (MACE), defined as a composite of future myocarditis, pericarditis, heart failure admission, atrial or ventricular arrythmia, heart transplantation, or all-cause death. Demographic, clinical and CMR characteristics were compared using the Wilcoxon signed-rank test for continuous variables and McNemar’s chi-squared test for categorical variables. P-values less than 0.05 were considered statistically significant.

Results: The cohort included 12 LC cases and 12 matched controls with presumed viral myocarditis. Chest pain at index presentation was less common among LC patients, though not statistically significant (41.7% vs. 83.3%; P-value=0.06). Regarding CMR characteristics, LC was associated with higher baseline median left ventricular (LV) ejection fraction (60.5% vs. 50.5%; P-value=0.02), as well as higher degrees of LV global longitudinal (-14.8% vs. -11.7%; P=0.03), circumferential (-15.5% vs. -12.6%; P=0.03), and radial (24.4% vs. 18.2%; P-value=0.03) strains. Notably, the degrees of right ventricular strain, as well as patterns and locations of late gadolinium enhancement were similar between groups. Over a mean follow-up of 2.6 years, there was no significant difference in MACE incidence between groups.

Conclusion: To our knowledge, this is the first study to characterize CMR findings in LC compared to viral myocarditis. Patients with LC presented with higher LVEF and less impaired LV strain measures. Given prior associations of these parameters with adverse cardiovascular events, LC may represent a relatively benign myocarditis phenotype, compared to other etiologies. Ongoing research will further clarify the unique CMR profile of LC, and its long-term prognostic implications.

Demographic, clinical and CMR characteristics among Lyme carditis patients compared with age- and sex-matched viral myocarditis patients

	Lyme carditis (n=12)	Non-Lyme viral myocarditis  (n=12)	P-value
Demographics
Age at diagnosis, median (Q1-Q3)	62 (28-65)	63 (28-66)	0.021
Male sex	11 (91.7)	11 (91.7)	--
White race	10 (83.3)	11 (91.7)	0.322
Active smoker	7 (58.3)	2 (16.7)	0.0592
Active alcohol use	10 (83.3)	6 (50.0)	0.0462
Active marijuana use	0 (--)	1 (8.3)	--
Past medical history
Hypertension	5 (41.7)	4 (33.3)	0.562
Hyperlipidemia	2 (16.7)	3 (25.0)	0.562
Diabetes	1 (8.3)	1 (8.3)	1.002
Prior myocardial infarction	0 (--)	1 (8.3)	--
Atrial fibrillation or flutter	1 (8.3)	2 (16.7)	0.562
Ventricular arrhythmia	0 (--)	1 (8.3)	--
Chronic Kidney Disease	0 (--)	1 (8.3)	--
HF with preserved ejection fraction ( >50%)	0 (--)	1 (8.3)	--
HF with reduced ejection fraction (< 40%)	0 (--)	1 (8.3)	--
Obstructive Sleep Apnea	2 (16.7)	1 (8.3)	0.562
Family history of cardiomyopathy or sudden cardiac death	0 (--)	2 (16.7)	--
Percutaneous coronary intervention at presentation	3 (25.0)	5 (41.7)	0.412
Active non-skin cancer	0 (--)	1 (8.3)	--
On immunosuppressive agent	0 (--)	1 (8.3)	--
Symptoms at presentation
Dyspnea	4 (33.3)	7 (58.3)	0.322
Chest Pain	5 (41.7)	10 (83.3)	0.0592
Atrial arrythmia	0 (--)	2 (16.7)	--
Ventricular arrythmia	0 (--)	1 (8.3)	--
Constitutional symptoms (fevers, chills, illness)	4 (33.3)	6 (50.0)	0.322
Hospitalization characteristics
Hospital length of stay, median (Q1-Q3)	4.5 (3.5-7.5)	4 (3-7)	0.271
ICU Admission	5 (41.7)	7 (58.3)	0.411
ICU length of stay, median (Q1-Q3)	(n=5)  7 (4-10)	(n=6)  3 (3-4)	**
Advanced cardiac support during admission	0 (--)	1 (8.3)	--
Cardiac MRI characteristics
LVEDV, median (Q1-Q3)	167.2 (141.5-179.5)	162.5 (127.5-257.5)	0.351
LVESV, median (Q1-Q3)	58.5 (52.5-75.5)	80.5 (50.5-194)	0.141
LVSV, median (Q1-Q3)	98 (78.5-118.2)	78 (59.5-85.5)	0.091
LVEF, median (Q1-Q3)	60.5 (58.5-66.5)	50.5 (32-58)	0.021
LVGLS, median (Q1-Q3)	-14.8 (-16.4 to -13.7)	-11.7 (-14.3 to -7.6)	0.031
LVGCS, median (Q1-Q3)	-15.5 (-17.4 to -14.6)	-12.6 (-14.5 to -8.5)	0.031
LVGRS, median (Q1-Q3)	24.4 (21.6-30.2)	18.2 (9.9-21.3)	0.031
RVS, median (Q1-Q3)	-21.2 (-23.2 to -19.1)	-20.2 (-22.8 to -13.9)	0.121
LGE Location
Lateral LGE	7 (58.3)	10 (83.3)	0.182
Septal LGE	5 (41.7)	5 (41.7)	1.002
LGE Pattern
Transmural LGE	0 (--)	2 (16.7)	--
Subepicardial LGE	6 (50.0)	7 (58.3)	0.742
Midmyocardial LGE	7 (58.3)	6 (50.0)	0.652