Cardiovascular Manifestations and Outcomes in Patients with Scrub Typhus Admitted to a Tertiary Care Center in the Coastal Karnataka Region in India

<b>Introduction</b>: Scrub typhus is a mite-borne infectious disease caused by "<i>Orientia tsutsugamushi</i>", a bacterium that was formerly classified under the genus Rickettsia. It is transmitted to humans through the bites of infected chigger mites (larval trombiculid mites). However, clinical data on the cardiac manifestations of scrub typhus and their outcomes remain limited. <b>Methods</b>: This research was retrospectively conducted at a tertiary care hospital in South India. The study included all patients admitted from January 2016 to September 2021 who fulfilled the clinical criteria for a diagnosis of scrub typhus. Data were collected for 426 patients. Patients with previously diagnosed heart disease and mixed infections (leptospirosis, dengue fever, blood culture positivity, and COVID-19 positivity) were excluded. Comprehensive assessments of clinical presentation, electrocardiography (ECG), 2D echocardiography, and outcomes, including all-cause mortality and probable myocarditis, were performed. Multivariate regression analysis was performed to identify independent predictors of all-cause mortality and probable myocarditis. <b>Results</b>: Out of 426 patients, 200 (46.9%) were male and 226 (53.1%) were female. The mean age at presentation was 49.29 ± 14.43 years. A total of 108 (25.4%) patients had diabetes and 82 (19.25%) had hypertension. Sinus tachycardia (29.3%) was the most frequent ECG finding. Echocardiographic evidence of probable myocarditis was observed in 20 (4.7%) patients, while 6 (1.4%) patients had isolated RV dysfunction, 4 (0.9%) had biventricular dysfunction, 7 (1.6%) had significant pulmonary hypertension, and 40 (9.4%) had trivial pericardial effusion. A total of 78 (18.3%) patients had acute respiratory distress syndrome. All-cause mortality was observed in 12 (2.8%) patients. A total of 56 (13.1%) patients developed multiorgan dysfunction syndrome (MODS) during their hospitalization. A total of 78 (18.3%) patients were documented to have acute kidney injury (AKI), and 22 (5.2%) patients underwent hemodialysis. Multivariable binary logistic regression analysis revealed that probable myocarditis and MODS were independent predictors of mortality among patients with scrub typhus, and age, female gender, and LV systolic dysfunction were identified as predictors of overall complications, including mortality, probable myocarditis, congestive heart failure, MODS, AKI, and the need for hemodialysis. <b>Conclusions</b>: Probable myocarditis was the most frequent cardiac manifestation noted in patients with scrub typhus, and in addition to MODS, probable myocarditis was an independent predictor of mortality in this cohort. Thus, it is crucial to maintain clinical vigilance regarding the cardiac status of such patients.