Index microvascular resistance (IMR) in heart transplant patients (IMR-HT study): Study protocol

Area of Science:

• Cardiology
• Transplant Surgery
• Vascular Physiology

Background:

• Acute allograft rejection (AAR) is a significant cause of mortality in heart transplant (HT) patients within the first year.
• Endomyocardial biopsy (EMB) is the standard for guiding post-transplant treatment but carries risks.
• Index of microvascular resistance (IMR) assesses microvascular function and may identify patients at high risk for adverse events.

Purpose of the Study:

• To evaluate IMR in heart transplant patients within the first year post-transplant.
• To assess changes in clinical management based on IMR values.
• To determine the long-term prognostic implications of IMR.

Main Methods:

• The IMR-HT study is a multicenter, prospective study of stable post-HT patients.
• Coronary physiological assessment including IMR will be performed at three months and one year.
• Cardiac adverse events will be monitored for up to five years.

Main Results:

• Early elevated IMR is linked to AAR, increased mortality, and adverse cardiac events.
• Low IMR values may support a reduction in the number of EMBs.
• IMR assessment can guide risk stratification and inform treatment adjustments.

Conclusions:

• IMR values can fluctuate within the first year after heart transplantation.
• IMR assessment is valuable for identifying high-risk heart transplant recipients.
• Utilizing IMR may lead to modified management strategies and improved prognosis.