The main early clinical concern in heart transplant (HTx) recipients is acute rejection, whereas cardiac allograft vasculopathy (CAV) remains a major cause of morbidity and mortality beyond the first year. The gold standard for the diagnosis of HTx rejection is Endomyocardial biopsy (EMB). However, this is an invasive procedure that needs to be performed serially and it is not free of complications. Alternatively, many non-invasive imaging techniques have been proposed for an early diagnosis of cardiac allograft injury. 

Non-invasive diagnostic tools allow continuous surveillance, providing useful diagnostic and prognostic insights. Unfortunately, they have a limited sensitivity and specificity. These include:

  • Electrocardiography

  • Biomarkers (i.e. troponin and natriuretic peptides)

  • Echocardiography (i.e. tissue Doppler, global longitudinal strain, and speckle-tracking)

  • Magnetic resonance imaging

  • Positron emission tomography. 

A large multicentre study was done providing a comprehensive intracoronary physiology assessment early and 1 year after HTx. FFR was used to evaluate epicardial coronary physiology, whereas both coronary flow reserve (CFR) and IMR were used to assess microvascular dysfunction. Concomitantly, IVUS was used to gain anatomical information. FFR, IMR, and CFR were performed in 254 patients early after HTx (median 7.2 weeks) and in 240 patients at 1 year. Patients were classified into three strata [normal physiology, abnormal epicardial physiology (FFR ≤0.80), and microvascular dysfunction (IMR ≥25 or CFR ≤2 with FFR >0.80].

At baseline, 5.5% of patients had abnormal epicardial physiology and 36.6% had microvascular dysfunction; at 1 year, 5% had abnormal epicardial physiology whereas 23.8% showed microvascular dysfunction. Abnormal epicardial or microvascular physiology at baseline was not related to long-term clinical outcomes. However, both abnormal epicardial physiology [adjusted hazard ratio (HR) 3.7] and microvascular dysfunction (adjusted HR 2.35) at 1 year were independent predictors of death and repeat HTx at 10 years (primary outcome measure).

This was mostly a result of newly developed microvascular dysfunction. Importantly, intracoronary physiology data were able to improve the prognostic performance of classic clinical variables. However, IVUS-derived changes in intimal thickness were not predictive of adverse events. These investigators suggested that invasively assessing coronary physiology in HTx recipients may identify those potentially benefiting from a close follow-up and early therapeutic interventions.



Investigation Modality,Investigation and Imaging,Electrophysiology,Nuclear Cardiology,Electrocardiography,Echocardiography,MRI,CT scan,Electrophysiologic Testing