Infective endocarditis is a silent epidemic. Its incidence has doubled in developed countries over the past two decades. Key contributing factors likely include population aging, increasingly aggressive medical interventions (both cardiac and non-cardiac), a criticized relaxation in infectious prophylaxis recommendations (highlighted in previous blog entries), and misuse of antibiotic therapy, leading to the emergence of multi-resistant organisms. In this context, our country is not an exception to this trend. As surgeons, we are—or should be—part of the so-called Endocarditis Team, responsible for decision-making in highly complex patients, where the possibility of performing surgery remains a differentiating factor in prognosis for these patients.

The study, published from the perspective of cardiologists and public health experts, provides a snapshot of the current situation in Spain, as reported in Revista Española de Cardiología. For data collection, they relied on the Spanish Minimum Basic Data Set (MBDS), identifying cases treated from 2016 to 2019 across institutions affiliated with the Spanish National Health System, which covers 98.4% of healthcare services. The MBDS enabled demographic data collection alongside secondary diagnoses coded according to ICD-10 criteria.

While the authors’ effort is commendable, it is essential to note that such methodologies typically introduce significant biases that may distort final results. Episodes lacking identification of a causative pathogen were excluded, potentially omitting cases with reporting errors or those with negative cultures. This is crucial since some of the most aggressive forms of endocarditis caused by pathogens like Coxiella, Mycobacterium (e.g., M. chimaera), fungi, or T. whipplei, among others, often present with negative cultures. Additionally, cases where patients did not declare their status at discharge (due to administrative errors) and those under 18 years (though rare) were not considered. Given these limitations, it is anticipated that some degree of misclassification may exist for comorbidities captured in variables such as renal insufficiency, diabetes, cancer, malnutrition, parenteral drug use, pre-existing valvular disease, prior valve prosthesis, or implanted cardiac electronic devices; the Charlson index score; and in-hospital morbidity and mortality, including heart failure, cardiogenic shock, systemic embolism, stroke, septic shock, acute renal failure, and the need for cardiac surgery. Furthermore, statistical inference to compare groups (surgery vs. no surgery, inter-regional differences) was limited to age and sex adjustments.

The study ultimately identified 9,008 episodes of infective endocarditis over the four years. Based on the population receiving healthcare, an incidence rate of 5.7 cases per 100,000 inhabitants was estimated, being twice as high in men (8.7 cases/100,000) as in women (3.7 cases/100,000). This figure represents an upward trend, aligning with reports from other countries, with previous incidence set at 3.49 cases/100,000 inhabitants in a similar study from 2014. The mean age was 69.5 years, with a comorbidity rate commonly encountered in our practice, and a median Charlson index of 2. Prevalence of pre-existing conditions included 36.8% with prior valvular disease, 26.8% with a prosthetic valve, and 10.6% with an implanted cardiac electronic device. The most frequently isolated pathogens were Staphylococcus (33.3%, with 19% being S. aureus and 14.3% coagulase-negative staphylococci), followed by Streptococcus (20.8%) and Enterococcus(15.3%). Episodes of culture-negative endocarditis comprised over 20% of cases. During hospitalization, the most common complication was heart failure (38.6%), followed by acute renal failure (27.5%) and stroke (11.1%). The average hospital stay was 26 days, a relatively short period, likely due to a low rate of surgical treatment (less than 20% across the series) and probable outpatient management of antibiotic therapy in many cases (length of stay ranging from 13 to 43 days). Overall in-hospital mortality reached 27.2%, contextualized by a low rate of operability and the severity of the disease.

As noted earlier, the multivariate models developed from the collected data lack full reliability. However, they reinforced established knowledge: patients with the worst prognosis presented with cardiogenic shock, septic shock, and/or cerebral embolism, while patients selected for surgery had a better prognosis than those who did not undergo surgery. This study’s true value lies in exposing the considerable differences in cardiovascular health service quantity and quality across the various autonomous communities, each with its health service framework. The disparities affected multiple aspects highlighted below:

• Incidence: Lower in the central plateau (except Madrid) and the Levante region (except Catalonia), paradoxically, areas with a predominantly older population.

• In-hospital mortality: Adjusted by incidence, it was lowest in Galicia, Catalonia, Madrid, and the Balearic Islands, followed by Castile and Leon and the Basque Country.

• Cardiac surgery rates: Most communities had rates below 20%, with only Andalusia, Asturias, the Canary Islands, Cantabria, Extremadura, Madrid, Murcia, and the Basque Country surpassing this threshold.

• Referral to specialized centers: Only less than one-third of declared cases in each community were referred, with Andalusia, Aragon, Asturias, the Canary Islands, Cantabria, Valencia, Extremadura, Madrid, Murcia, and the Basque Country exceeding this threshold. The authors emphasize and corroborate with their analysis the benefits of being treated in hospitals that include cardiac surgery in their service portfolio, which allows for higher rates of pathogen identification (intraoperative culture samples).

• Microbiological profile: The different regions showed variations in the frequency with which agents caused episodes of endocarditis, with no clinically or ecologically relevant differences, other than some statistically significant but difficult-to-explain findings. Particularly notable were the following aspects:

• Failure rates in identifying the causative pathogen in blood cultures: Especially high in Andalusia, the Canary Islands, Castile-La Mancha, Castile and Leon, and Extremadura. These regions tend to have high rurality rates, smaller hospitals, and likely difficulties in sending viable samples to reference laboratories or limited access to centers with cardiac surgery.

• Prosthetic endocarditis rates: Showed a north-south gradient, being higher in northern communities (Castile and Leon, Galicia, the Basque Country, or Asturias, each exceeding 30% of cases).

• Endocarditis associated with intravenous drug use: Although not comparable to the epidemic levels in countries like the USA, it was concentrated in regions such as Catalonia, Valencia, Murcia, and Madrid, where it accounted for over 2% of cases.

COMMENTARY:
This work is very much appreciated and, despite potential inaccuracies, serves as an indictment of the social injustice represented by the disparity in healthcare across 17 different health systems within the same country. Some intriguing data relate to the demographic, economic, or geographic characteristics that we all recognize and that influence microbial etiolo0808gy, referral possibilities to tertiary centers, and, most concerning, survival or surgical treatment rates. Sometimes, we feel inadequate comparing ourselves to other countries (especially in Europe) when working in or receiving care from our so-called “best healthcare system in the world.” Yet what I find intolerable is that two people receiving care in the same country have different outcomes simply because they are in neighboring communities. No healthcare system is perfect, but decades of reassurance about having the best have led to a complacent acceptance of a situation that is increasingly unacceptable. Our healthcare system may indeed excel in some areas, like organ transplants, be among the most compassionate, and efficient (at the expense of healthcare professionals’ salaries). However, in terms of quality and uniformity, we cannot settle for less, especially in the 21st century, when, against a probabilistic disease like endocarditis, some Spaniards still lack equal chances of overcoming it. 

REFERENCE:

Zulet P, Olmos C, Fernández-Pérez C, Del Prado N, Rosillo N, Bernal JL, et al. Regional differences in infective endocarditis epidemiology and outcomes in Spain. A contemporary population-based study. Rev Esp Cardiol (Engl Ed). 2024 Sep;77(9):737-746.