Index microvascular resistance (IMR)-guided management of heart transplantation (IMR-HT study): Study Protocol

ABSTRACT Background Acute allograft rejection (AAR) is an important cause of morbi-mortality in heart transplant (HT) patients, particularly during the first year. Endomyocardial biopsy (EMB) is the “gold standard” to guide post-heart transplantation treatment. However, it is associated with complications that can be potentially serious. Index of microvascular resistance (IMR) is a specific physiological parameter to measure microvascular function. An increased IMR measured early after HT has been associated with acute cellular rejection (ACR), higher all-cause mortality and adverse cardiac events. As far as we know, no study has evaluated IMR impact on post-HT management (number of EMB performed). Our aim will be to assess if post-HT patient management may be modified based on IMR value. Study design The IMR-HT study (NCT 06656065) is a multicenter, prospective study that will include post-HT consecutive stable patients undergoing coronary physiological assessment in the first three months and one year. Depending on IMR values the physician will be able to reduce the number of biopsies established in each center protocol. Conclusions Management after heart transplant (number of biopsies) could be modified depending on IMR values.