Characteristics and outcomes of patients with possible versus definite infective endocarditis: A nationwide cohort...

Distinguishing possible from definite infective endocarditis (IE) is challenging and may affect clinical decisions. A better understanding of how possible and definite IE differ, according to the ESC Duke criteria, may clarify the clinical relevance of this distinction.

To compare clinical characteristics and outcomes in patients with possible and definite IE.

We included all patients with a first episode of possible or definite left-sided IE from the NatIonal Danish endocarditis stUdieS (NIDUS) registry (2016-2021), classified according to the 2015 ESC modified Duke criteria. We assessed baseline characteristics and management, as well as six-month rates of IE-related outcomes and all-cause mortality.

Among 3,017 patients, 587 (19.5%) had possible IE and 2,430 (80.5%) definite IE. Patients with possible IE were older and more often had left-sided prosthetic valves (35.4% vs. 25.8%) and culture-negative IE (30.0% vs. 2.2%), but less often vegetations >10 mm (13.6% vs. 32.8%) (all p < 0.001). Complications and cardiac surgery (10.9% vs. 24.6%) were less frequent in the possible IE group. Antibiotic treatment was shorter in possible IE (median days 37 vs. 40; p = 0.01). Six-month all-cause mortality was similar: 27.4% [95% CI: 23.8-31.1] vs. 28.1% [95% CI: 26.3-29.9], as were IE-related outcomes.

Patients with possible IE more often had left-sided prosthetic valves and culture-negative IE, but less often vegetations >10 mm, complications or cardiac surgery, and received shorter antibiotic treatment. Clinical outcomes were similar. These findings highlight diagnostic challenges and the need for tailored diagnostic and treatment strategies.