Background
Lyme carditis is a rare and potentially fatal manifestation of Lyme disease. Although Lyme disease is nationally notifiable, data on clinical manifestations are not collected systematically in the US. We sought to use a novel syndromic surveillance query to identify patients with Lyme carditis in New York State (excluding New York City) during 2017-2021.

Methods
Using the US National Syndromic Surveillance Program’s BioSense Platform, we developed a query to identify emergency department visits related to Lyme carditis. We systematically abstracted key information in each identified medical record through New York’s regional health information exchange system. Two physicians independently assigned a clinical case status (confirmed; probable; not a case) to each record; when adjudications differed, an infectious disease physician provided a final adjudication. Positive predictive value for the query was calculated and characteristics of cases and non-cases were described.

Results
The query identified 175 individuals. Records were available for 139 individuals. Among these, 37% (n = 52) were classified as confirmed, 17% (n = 24) as probable, and 45% (n = 63) as not a case. In total, we identified 76 cases of confirmed or probable Lyme carditis for which records were available; the positive predictive value of the query was 45%. Cases occurred in 28 of New York’s 57 counties; most (64%) occurred during May–September. Median age was 60 years for cases (IQR 33 – 73) and 67 years for non-cases (IQR 42 – 78) (p = 0.13); 29% of cases and 38% of non-cases were female (p = 0.23). Among cases, 76% had positive immunoblots and 37% had second- or third-degree atrioventricular block.

Conclusion
Using a syndromic surveillance query, we detected 76 cases of Lyme carditis. This query may be a useful tool to detect changing disease patterns, including temporal or spatial clusters of severe Lyme disease manifestations.