Clinical Features and Outcomes of Acute Myocarditis in Patients with Swab-Confirmed Respiratory Viral Pathogens.

BACKGROUND

Acute myocarditis (AM) is an inflammatory cardiac condition with heterogeneous clinical manifestations that often overlap with other acute cardiac syndromes, making diagnosis challenging.

OBJECTIVES

To characterize the prevalence, clinical profile, and outcomes of AM patients with respiratory viral pathogen detection on nasopharyngeal swabs at admission.

METHODS

We retrospectively analyzed all patients admitted to the Sheba Medical Center with confirmed AM between January 2005 and December 2020. Diagnosis was based on compatible presentation, elevated cardiac biomarkers, and supportive imaging findings. Nasopharyngeal swab results, when performed, were reviewed for respiratory viral detection.

RESULTS

Among 425 identified AM cases, 146 (34%) underwent swab testing; 11 (8%) tested positive for respiratory viral pathogens, most commonly influenza A (n=5) and adenovirus (n=3). With one exception, all positive cases occurred during winter or early spring (10/77, 13%). Compared with swab-negative patients, swab-positive individuals were older (47 ± 22 vs. 35 ± 14 years, P = 0.03), more frequently female (45% vs. 14%, P = 0.007), and more often presented with dyspnea (55% vs. 25%, P = 0.036) but less commonly with ST-segment elevation (27% vs. 70%, P = 0.003). No differences were observed in inflammatory markers, imaging findings, or hospital stay.

CONCLUSIONS

Respiratory viral detection in AM is uncommon and predominantly seasonal. Nasopharyngeal swabbing is a simple, non-invasive tool that may help identify treatable viral pathogens and guide patient management. These data provide a pre-COVID-19 reference for future studies investigating the impact of viral infection on myocardial injury.