Cardiologia Croatica. 2022;17(1-2)

Branko Lozić, Điđi Delalić, Domagoj Marković, Tomo Svaguša, Ingrid Prkačin

Chronic kidney disease (CKD) is characterized by gradual progressive loss of all kidney functions over a period of time. One-fifth of men and one-quarter of women over the age of 65 suffer from CKD. Given the growing incidence of diabetes and hypertension, which are the main causes of this disease, CKD is becoming one of the major global public health issues. Cardiovascular diseases are the leading cause of death in people with CKD, primarily heart-related conditions such as ischemic heart disease and heart failure. High-sensitivity troponins (hs-cTnT, hs-cTnI) are crucial biomarkers used in the detection of cardiac pathology. They are mostly used in the detection of acute coronary syndrome, but elevated values can be also observed in several other conditions. Studies have shown that serum troponin levels are elevated in more than two-thirds of patients with CKD on dialysis, even in those without any cardiovascular pathology. The aim of this review was to examine the literature and to determine the reason for troponin increase in patients with CKD, and to establish whether there is a connection between their increase and the mortality rate. A literature search revealed that patients with end-stage renal disease (ESRD) are at especially high risk of cardiovascular morbidity and mortality. Studies have also found a strong association of high-sensitivity troponins with cardiovascular and all-cause mortality in those patients. On the other hand, even though the function of troponins is very well-known, little is known about their production and excretion from the body. The theory that troponins are excreted by the kidneys is becoming widely accepted in scientific circles. New studies, some of which are Croatian, have demonstrated the presence of troponins in urine, but further research is needed to determine whether it is possible to use troponins in urine as potential biomarkers for cardiovascular and kidney disease.

Zainab Atiyah Dakhil

The coronavirus disease-2019 (COVID-19) pandemic has significantly disrupted cardiology services (1) and subsequently fellowship training worldwide, due to the decline in volume of cardiac procedures and re-allocating fellows to frontline services and COVID-19 designated hospitals or areas of need (intensive care units). (2-4) Mentorship and networking opportunities declined remarkably, as did research and academic opportunities, aside from the impact of the pandemic on the physical and mental health of fellows. In the context of such challenges, there is a crucial need for cardiology fellowship programs to extend beyond **robustness** (the system can absorb and recover from shocks with no major negative consequence) and **resilience** (the system can function and adapt to the shocks with dynamic changes to cope with needs) (5, 6) by adopting **antifragility** (the system can adapt the shock and stressors and become stronger). (7) This should be our ultimate goal in the COVID-19 era and beyond, in order to maintain cardiology training competency with subsequent positive impacts on cardiac services and procedures. When Taleb used the term “antifragility”, he described the systems that can “benefit from shocks” and “thrive and grow when exposed to volatility, randomness, disorder, and stressors and love adventure, risk, and uncertainty”. (8, 9) Despite the dramatic positive impacts of COVID-19 vaccines, it does not seem that the pandemic crisis will end soon, given that countries are suffering multiple subsequent COVID-19 waves, especially with the new strains keep appearing (with Omicron causing the latest wave). This makes building antifragile healthcare system crucial, so that the systems not only survive but also thrive during the pandemic. Two points should be kept in mind: firstly, the training environment provided by a healthcare facility to its trainees determines the healthcare services it can provide to patients, and secondly, the fellows have a unique position in confronting this pandemic, so we have a commitment to maintaining cardiovascular fellowship training integrity and competency. In this letter, we propose certain measures to achieve the antifragile training program by establishing a specific framework to support FITs competency through the implementation of certain practical steps across professional and academic aspects of FITs careers (**Figure 1**). FIGURE 1. Recommendations to implement the antifragile cardiovascular training program during COVID-19 pandemic and beyond. Despite the fact that crises such as the COVID-19 pandemic create extreme stress on healthcare systems, they can also create opportunities to learn and build new system frameworks that not only resist the crisis but benefit from it. Virtual science, better application of simulation training, learning how important is to prioritize cardiac services, importance of heart teams and flow of cardiac services in crisis, telemedicine implementation, wide use of social media in professional advancement, research collaboration beyond geographical borders despite absence of in-person communication: all these are lessons learned from this pandemic, and, if applied properly, will map a new era in cardiovascular training, research, and care.