Shorter antibiotic regimens for clinically stabilized left-sided infective endocarditis patients improve days alive without therapy and reduce overall drug exposure without increasing major clinical complications, according to the open-label randomized POET II trial presented at the European Society of Cardiology Congress.
POET II Trial Design and Clinical Stability Criteria
Infective endocarditis is a severe, life-threatening infection of the heart valves or implanted cardiac devices, traditionally managed with prolonged courses of high-dose intravenous or oral antibiotics lasting four to six weeks. This extended approach relies largely on expert consensus because clinicians have lacked a definitive biomarker to confirm bacterial clearance. To challenge this medical dogma, investigators in the open-label randomized POET II trial evaluated a tailored, response-driven antibiotic strategy for adult patients with infective endocarditis affecting native or prosthetic valves on the left side of the heart. The study cohort comprised 508 randomized participants across centers in Denmark, Sweden, and the United States, with a mean age of 70 years, and three-quarters identifying as men.
Before any randomization took place, patients achieved clinical stability following a minimum of two to four weeks of initial antibiotic therapy. Investigators determined this stabilization point by applying a combination of clinical, biochemical, and imaging criteria established in the earlier POET trial. Once stabilized, participants were randomized in a 1:1 ratio either to stop antibiotic treatment entirely under a tailored approach or to continue standard-of-care therapy for a full cumulative duration of four to six weeks. The primary objective was to evaluate whether a shortened, personalized course could safely reduce total antibiotic exposure without compromising patient outcomes.
Comparing Outcomes: Patient-Days Without Therapy and Safety Endpoints
The tailored antibiotic strategy delivered measurable advantages in overall recovery time and reduced drug exposure. Overall, patients in the tailored group took antibiotics for a median of 26 days, representing a reduction of 15 days compared with the standard median of 41 days.
Regarding the primary safety endpoint, the tailored regimen met noninferiority criteria. It was associated with no excess all-cause mortality, unplanned cardiac surgery, or symptomatic embolic events within six months, occurring in 8.2% of the tailored-therapy group versus 10.7% of the standard-therapy group. Henning Bundgaard, MD, of the University of Copenhagen in Denmark, highlighted the broader implications of these findings during a press briefing at the European Society of Cardiology Congress in Munich.
Pathogen-Specific Risks and the Challenge of Enterococcus faecalis
While the overall safety endpoint favored the tailored approach, secondary analyses revealed important nuances linked to the specific bacterial pathogens involved. Approximately 70% of all infective endocarditis cases are driven by three primary Gram-positive pathogens: Streptococcus species, Staphylococcus aureus, and Enterococcus faecalis. In the POET II trial, Streptococcus species were the most common pathogen, appearing in 57.3% of patients, followed by S. aureus in 24.2%, and E. faecalis in 18.5%. Background data indicate that E. faecalis is particularly prevalent among patients over 70 years of age according to quality reports examined in cell and developmental biology literature.
When examining composite safety endpoints by organism, tailored therapy held a clear advantage when streptococcal and S. aureus infections were the causes, showing safety endpoint incidence rates 3.6 percentage points lower with streptococcus species and 6.4 percentage points lower with S. aureus. However, E. faecalis infections told a different story. Composite safety endpoint incidence rates were 6.8 percentage points lower among standard-therapy patients than tailored-therapy patients when E. faecalis was the causative pathogen.
Relapse rates also varied significantly across pathogens. A return of bacteremia or infective endocarditis during the six-month follow-up occurred more frequently in the tailored-therapy group overall (5.1%) than in the standard-therapy group (1.6%). Relapse was particularly notable among E. faecalis patients at 6.4%, compared with 3.3% for S. aureus and 2.4% for streptococcal patients. Investigators cautioned that firm conclusions regarding E. faecalis remain limited because the study did not recruit its planned number of patients with that specific infection.
Evaluating the Trade-off Between Relapse Risk and Antimicrobial Exposure
Shorter antibiotic courses are attractive to clinicians and researchers seeking to minimize drug side effects, curb the rising threat of antimicrobial resistance, improve patient recovery, and lower healthcare costs. Yet the higher incidence of infection relapse associated with shortened therapy requires careful clinical evaluation. Study authors emphasized that while standard therapy was linked with a significantly lower risk of relapse, the broader clinical context matters greatly for patient management.
Summarizing the rationale for accepting a managed trade-off, study authors argued that considering the potential benefits of a reduction in antibiotic exposure, an increase in the risk of relapse could be deemed acceptable if it is not associated with major clinical complications
. Sensitivity analyses incorporating relapse into the primary safety endpoint remained reassuring for patients with infective endocarditis caused by streptococcus species or S. aureus, even though more events emerged among the E. faecalis subgroup in the tailored-therapy arm.
