Influenza worsens AMI outcomes

Patients with acute myocardial infarction (AMI) are likely to suffer from worse clinical outcomes in the presence of influenza and other viral infections, a recent study has shown.

Drawing from the National Inpatient Sample, researchers identified 1,884,985 AMI admission, 1.1 percent of whom were positive for infections. There were 9,885 AMI patients with influenza (mean age, 72.3±14.0 years; 47.8 percent female) and 11,485 with other viral respiratory infections (mean age, 71.9±14.2 years; 48.4 percent female).

Clinical outcomes were worst in patients who had concomitant influenza. In-hospital case fatality rate, for example, was highest in these patients as opposed to those with other viral respiratory infections and without any viral infections (13.5 percent vs 7.5 percent and 8.6 percent; p<0.001).

The same was true for acute respiratory failure (19.2 percent vs 10.1 percent and 10.2 percent; p<0.001), acute kidney injury (40.3 percent vs 31.0 percent and 24.2 percent; p<0.001) and length of stay (9.3±10.3 vs 7.5±8.6 and 5.8±7.3 days; p<0.001), among other important outcome measures.

These differences remained significant even after propensity-score adjustment.

Relative to those without concomitant influenza, AMI patients with the infection were more likely to die while admitted (13.2 percent vs 9.6 percent; p<0.001) and to develop acute respiratory failure (53.0 percent vs 28.8 percent; p<0.001) and acute kidney injury (40.2 percent vs 28.6 percent; p<0.001).

These findings were generally untrue in AMI patients who had other viral respiratory infections, except for acute respiratory failure, which occurred at a much higher frequency than in the no-infection comparators.