Association among myocardial injury and mortality in Influenza: A prospective cohort study

Background: Myocardial injury (MINJ) is a well-recognized prognostic marker in different acute cardio-respiratory illnesses, nonetheless, its relevance in Influenza remains poorly defined. Our aim was to assess incidence, correlates, short and mid-term prognostic role of MINJ in Influenza.

Methods: Hospitalized patients (pts) with laboratory confirmed Influenza A or B underwent highly sensitive cardiac T Troponin (hs-cTnT) measurement at admission in four regional Swiss hospitals during the 2018-2019 epidemic. MINJ was defined as hs-cTnT >14 ng/L. Clinical, laboratory and outcome data were prospectively collected. The primary endpoint was mortality at 28 days while the composite of mortality, admission to intensive care unit (ICU) or need for mechanical ventilation at 28-days and mortality at 30-months were set as secondary endpoints.

Results: The presence of MINJ was assessed within 48 h from admission in 145 consecutive hospitalized pts, being evident in 94 (65.5%) pts and associated with older age, higher C-reactive protein levels, renal impairment or chronic obstructive pulmonary disease. At a 28-days follow-up, 7 deaths (4.8%) occurred, all in patients with MINJ at admission (log-rank p = 0.048). MINJ was strongly associated with occurrence of death, ICU admission or mechanical ventilation (OR 5.74, 95% CI 1.28-53.29; p = 0.015). After a median follow-up of 32.7 months (IQR 32.2-33.4), 15 (10.3%) deaths occurred, all among pts with MINJ at index hospitalization leading to a higher mortality at follow-up among patients with MINJ (log-rank p = 0.003).

Conclusions: MINJ is common in patients hospitalized for Influenza and is able to stratify the risk of short-term adverse events and mid-term mortality.