Description

The 2021 ESC guidelines for the prevention and treatment of cardiovascular diseases in clinical practice emphasize the importance of proper screening and management of sarcopenia. Sarcopenia is defined as a progressive and generalized skeletal muscle disorder characterized by accelerated loss of muscle mass and function, which is associated with various adverse outcomes including falls, fractures, functional decline, and increased mortality. Although sarcopenia has traditionally been regarded as an age-related syndrome (primary sarcopenia), the condition is not exclusive to older populations. Increasingly, sarcopenia is being identified in younger individuals suffering from specific or multiple chronic diseases (secondary sarcopenia).

Secondary sarcopenia is particularly relevant in patients with cardiovascular disease. For example, in a study done in China, 78 (22.6%) out of the 345 enrolled participants who were hospitalized for coronary heart disease were found to have sarcopenia. Even higher prevalence rates were observed in Brazil where 64.6% and 35.4% of the 99 elderly patients with myocardial infarction presented with sarcopenia and sarcopenic obesity, respectively. Unlike the slow progression observed in primary sarcopenia, secondary sarcopenia can develop acutely, for instance within days following an acute hospital admission, leading to rapid deterioration of muscle mass and function. Acute sarcopenia, lasting \<6 months, is typically related to acute illness, injury or hospitalization, and is reversible if appropriate treatment (e.g., exercise, nutrition) is initiated in a timely manner.

Nevertheless, sarcopenia remains frequently underrecognized in current clinical practice among patients recovering from cardiac surgery. Traditional cardiovascular risk assessment does not account for sarcopenia or frailty, instead relying on age and comorbidities as indirect measures. Consequently, sarcopenia is often underdiagnosed. This lack of awareness results in many patients with sarcopenia not being identified in a timely manner, thereby missing opportunities for early and effective intervention.

Further, little is known about the trajectory of sarcopenia during the recovery process following cardiac surgery. While sarcopenia is increasingly recognized as a relevant prognostic factor in cardiac surgical patients, most available research focuses on its prevalence and cross-sectional associations at single time points, often preoperatively or in the early postoperative phase. The changes in muscle mass, strength, and function throughout the rehabilitation period remain poorly characterized.

Understanding the determinants and temporal evolution of sarcopenia in this patient population is of clinical importance for several reasons. First, the postoperative period is characterized by multiple interacting factors that can accelerate or mitigate acute muscle loss, including systemic inflammation, immobilization, nutritional status, metabolic changes, and the presence of comorbidities, leading to acute secondary sarcopenia. Second, the recovery trajectory after cardiac surgery varies between individuals, suggesting that the risk and reversibility of sarcopenia may differ over time. Third, there is currently little understanding of the key predictors of sarcopenia progression or recovery over time. Though, this knowledge would enable the development of early, targeted, and personalized interventions aimed at preserving or restoring muscle mass and function, ultimately improving functional outcomes, quality of life, and long-term prognosis.

Finally, at UZ Leuven, approximately 447 patients eligible for cardiac rehabilitation currently enroll in the program on a yearly basis (data from 2023). The percentage of patients with sarcopenia among this group of patients is unknown. This multidisciplinary program has consistently demonstrated substantial benefits in improving exercise capacity, with mean increases in peak oxygen uptake (VO₂peak) of 20%. However, it remains to be investigated whether the current rehabilitation program is sufficient to improve muscle mass and muscle function in patients with sarcopenia, or whether these patients require a more tailored approach. Given that sarcopenia involves both quantitative and qualitative deficits in skeletal muscle, and that improvements in aerobic capacity do not necessarily translate into parallel gains in muscle mass or strength, it is plausible that the current rehabilitation may be suboptimal for this subgroup. Addressing this knowledge gap is essential to ensure that rehabilitation strategies are not only effective in enhancing cardiorespiratory fitness but also in reversing or mitigating sarcopenia, thereby maximizing overall functional recovery and long-term prognosis.