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Cardiac Graft Assessment in the Era of Machine Perfusion: Current and Future Biomarkers

Heart transplantation remains the treatment of reference for patients experiencing end‐stage heart failure; unfortunately, graft availability through conventional donation after brain death is insufficient to meet the demand. Use of extended‐criteria donors or donation after circulatory death has emerged to increase organ availability; however, clinical protocols require optimization to limit or prevent damage in hearts possessing greater susceptibility to injury than conventional grafts. The emergence of cardiac ex situ machine perfusion not only facilitates the use of extended‐criteria donor and donation after circulatory death hearts through the avoidance of potentially damaging ischemia during graft storage and transport, it also opens the door to multiple opportunities for more sensitive monitoring of graft quality. With this review, we aim to bring together the current knowledge of biomarkers that hold particular promise for cardiac graft evaluation to improve precision and reliability in the identification of hearts for transplantation, thereby facilitating the safe increase in graft availability. Information about the utility of potential biomarkers was categorized into 5 themes: (1) functional, (2) metabolic, (3) hormone/prohormone, (4) cellular damage/death, and (5) inflammatory markers. Several promising biomarkers are identified, and recommendations for potential improvements to current clinical protocols are provided.

Optimizing the Assessment of Patient Clinical Risk at the Time of Cardiac Stress Testing

Due to a marked temporal decline in inducible myocardial ischemia over recent decades, most diagnostic patients now referred for cardiac stress testing have nonischemic studies. Among nonischemic patients, however, long-term risk is heterogeneous and highly influenced by a variety of clinical parameters. Herein, we review 8 factors that can govern long-term clinical risk: coronary risk factor burden; patient symptoms; exercise capacity and exercise test responses; the need for pharmacologic stress testing; autonomic function; musculoskeletal status; subclinical atherosclerosis; and psychosocial risk. To capture the clinical benefit provided by both assessing myocardial ischemia and these additional parameters, the authors propose that a cardiac stress tests report have an additional component beyond statements as to the likelihood of obstructive coronary artery disease and/or magnitude of ischemia. This added component could be a comment section designed to make referring physicians aware of aspects of long-term risk that may influence clinical management and potentially lead to changes in the intensity of risk factor management, frequency of follow-up, need for further testing, or other management decisions. In this manner, the increasingly frequent normal stress test result might more commonly influence treatment recommendations and even patient behavior, thus leading to improvement in patient outcomes even in the setting of normal stress test results.