Coinfection with infective endocarditis (IE) and spondylodiscitis (SD) has been inadequately studied, showing considerable variation across studies. It is estimated that up to 30% of patients with SD may have an IE coinfection. These differences arise from the simultaneous need for echocardiograms and spinal MRIs within a brief period, both essential for diagnosis. Access to these diagnostic tools depends on the protocols and department availability where the patient is admitted (Traumatology, Neurosurgery, Cardiology, Internal Medicine, Intensive Care, etc.). 

A recent multicenter study, the largest to date, was published in the European Journal of Cardio-Thoracic Surgery. This study examines IE and concomitant SD cases, focusing on the impact of treatment sequence on mortality and survival outcomes. The authors compared treatment sequences to assess survival rates and identify risk factors for survival and recurrence. This multicenter study in Germany involved 150 patients with IE+SD. Among them, 76.6% received primary surgery for IE, while 23.3% underwent initial treatment for SD. A univariable and multivariable analysis was performed, with inverse probability weighting (IPW) applied to minimize bias. 

Patients receiving initial SD surgery did so due to reasons such as neurological deficits, progressive painful spinal deformity, spinal instability, intraspinal empyema, or failed conservative treatment. In other cases, IE was addressed first, following recognized clinical guidelines. 

The findings revealed that, out of 3,991 patients with IE, only 150 had concurrent SD. Risk factors for this coinfection included an average age of 70 years, male gender, hypertension, diabetes mellitus, and chronic renal failure. Of these, 115 received initial IE surgery, and 35 were first treated for SD. Only 31 patients who underwent primary IE surgery subsequently required SD surgery; the rest received conservative treatment. However, all patients initially treated for SD subsequently required surgical intervention for IE. Compared to primary IE treatment, primary SD surgery resulted in significantly higher 30-day mortality and a trend toward increased 1-year mortality (25.7% vs. 11.4% at 30 days; 34.3% vs. 21.1% at 1 year). However, primary IE treatment showed higher recurrence rates for IE and SD at 30 days and 1 year. Mortality predictors included diabetes mellitus and primary SD treatment, which increased 30-day mortality, preoperative hemodialysis, and a BMI >25 kg/m², both of which elevated 1-year mortality risk. Recurrence predictors included chronic kidney disease, thoracic SD, and primary IE treatment. 

COMMENTARY:

In 25% of concurrent IE and SD cases, Enterococcus was isolated, in contrast to other pathogens commonly found in isolated IE cases. This observation aligns with other published series. The authors suggest spinal MRI for cases with Enterococcus, even with mild symptoms like controlled lumbar pain. 

Another noteworthy aspect is that while 30-day mortality is higher when SD is treated first, 1-year prognosis aligns, as observed in other series. This result, however, depends on early SD diagnosis and proper, complete antibiotic therapy. 

Recurrence rates of IE are significantly higher in patients first treated for IE, likely due to the conservative treatment of SD in most cases, leading to potential local relapse from inadequate infection control. 

Lastly, the study authors acknowledge limitations due to the multicenter nature, differing imaging protocols, diagnosis, and antibiotic therapy. While statistical tools aimed to reduce selection bias, inherent limitations may impact findings (noting, from the outset, that the SD primary treatment group was notably smaller than the IE group, initially limiting comparability). 

Despite the formerly mentioned, personally I thik we shoud focus on three ideas: 

• The coinfection frequency of IE and SD is low (ranging from 5% to 30%, depending on series), yet it significantly elevates mortality. This should prompt reflection on routine clinical practices, especially in cases without a primary focus. Are we potentially underdiagnosing or undertreating? Should we, as the authors suggest, incorporate protocolized MRI in all Enterococcus IE cases? 

• It appears safe to conclude that, in diagnosed cases, cardiac surgery for IE should be prioritized (per 2023 EACTS guidelines), but addressing the primary SD focus aggressively, if necessary, including surgery, remains equally critical. 

• Finally, it is essential to emphasize the value of collecting national data. The authors highlight the difficulties in gathering data due to the scarcity of reported cases, reminding Spanish surgeons of the importance of national registry contributions (e.g., the comprehensive, user-friendly RECC registry). I believe this is not only a need but an obligation to ensure future patients receive evidence-based, optimal treatment options. 

To conclude, my reflection today is (and hence the title used in this post); if we are limiting ourselves or focusing on treating the heart infection (what “kills the patient” in the short term and what we, as cardiovascular surgeons, control) and we are forgetting about the initial problem, in this case spondylodiscitis, which could be a primary focus like any other, even unknown, we would not be carrying out a complete treatment. 

REFERENCE: 

Weber C, Misfeld M, Diab M, Saha S, Elderia A, Marin-Cuartas M, et al. Infective endocarditis and spondylodiscitis-impact of sequence of surgical therapy on survival and recurrence rate. Eur J Cardiothorac Surg. 2024 Jul 1;66(1):ezae246. doi: 10.1093/ejcts/ezae246.