Spectrum of Cardiac Manifestations and its Relationship to Outcomes in Patients Admitted With Scrub Typhus Infection: A Prospective Observational Cohort Study From South India

Abstract

Background. Scrub typhus, a rickettsial illness caused by Orientia tsutsugamushi is endemic in the "tsutsugamushi triangle". It accounts for nearly 50% of cases of acute undifferentiated febrile illness in South India, and is associated with significant morbidity. Although the overall case fatality rate of patients admitted to hospital with scrub typhus infection is 9%, in those admitted with severe illness to the intensive care unit (ICU), mortality may be as high as 24%. It is known that scrub typhus can cause myocarditis and myocardial dysfunction. However, the magnitude of this problem and its impact on outcome is unclear. We describe the spectrum of cardiac manifestations in scrub typhus infection and assess its relationship to outcomes. Methods. Demographic data, electrocardiographic (ECG) changes, left ventricular (LV) and right ventricular (RV) systolic function, LV diastolic function, myocardial injury (defined as Troponin-T >14 pg/ml) and pericardial effusion were documented. Myocarditis was diagnosed when myocardial injury was associated with global LV systolic dysfunction. Logistic regression analysis was done to assess the impact of myocarditis on ventilatory requirements, length of hospital stay and mortality and expressed as odds ratio (OR) with 95% confidence interval (CI). Results. The cohort (n = 81; 35 male) aged 49.4 +/- 16.1 years (mean +/- SD) presented 8.1 +/- 3.1 days after symptom onset. Forty-eight patients (59%) required ventilation; 46 (56%) required vasoactive agents. The APACHE-II score was 15.7 +/- 7.0; overall mortality was 9.9%. ECG changes were non-specific; sinus tachycardia was the most common finding. Myocardial injury was evident in 61.7% and LV systolic dysfunction in 30.9%. A diagnosis of myocarditis was made in 21% (n = 17). Mild diastolic dysfunction was observed in 18%. Mild to moderate pericardial effusion was seen in 51%. Patients with myocarditis had increased ventilatory requirement (OR 4.24, 95% CI 1.11- 16.22) and prolonged hospitalization (OR 1.14, 95% CI 1.02-1.27). Myocarditis was not associated with mortality. Conclusion. In scrub typhus infection cardiac manifestations are frequent and associated with increased morbidity but not mortality.