Acute Heart Failure Exacerbation and Influenza Infection

Background: Influenza infection causes 3-5 million cases of severe illness annually and has been linked to exacerbations of congestive heart failure (CHF) as well as myocarditis. Patients with diagnosed CHF appear to have an increased risk of hospitalization during influenza season, but a relationship between serologically diagnosed influenza infection and acute heart failure (AHF) exacerbations has not been studied. Methods: This was a retrospective chart review studying patients with a diagnosis of CHF between April and October 2016 with specific focus on those presenting with AHF exacerbations until 2018. Descriptive data was collected regarding patient demographics, total number and dates of encounters, length of stay, presenting laboratory values, influenza testing Results, intensive care admission, and outcomes including mortality. This data was divided based on influenza testing status and univariate analysis was applied to capture any association of peak influenza infection with peak AHF encounters, correlation of influenza infection with length of stay, and correlation of influenza infection with patient demographics. Descriptive statistics were gathered on all variables of interest. Statistical significance was set at p-value \u3c 0.05. All analyses were performed using SAS 9.4. Results: Out of 1880 patients with a diagnosis of AHF exacerbation, there were two defined groups: influenza positive (n=28), and influenza negative/not tested (n=1852). There was no significance noted amongst the rate of heart failure exacerbations between these two groups (Table 1, p-value 0.134). Out of all variables analyzed, only two demonstrated statistical significance between influenza positive and influenza negative/not tested groups. Diagnosis of pulmonary hypertension (p-value 0.013) and coronary artery disease (p = 0.031) was more likely in influenza positive patients. No statistically significant correlation was found for the primary endpoint of influenza positivity with acute heart failure exacerbation. Conclusions: This data comprised a significant portion of patients with AHF exacerbations with negative influenza tests or those that were not tested. This allows us to deduce that perhaps a larger cohort of patients may be required to determine if there is true statistical significance of additional variables and endpoints. These Results also indicate a need for higher clinical suspicion of influenza infection in patients with heart disease, particularly coronary artery disease and pulmonary hypertension. Future studies may also focus on the effect of influenza treatment on hospital outcomes for cardiac patients