Inhomogeneous myocardial stress perfusion in SPECT studies predicts future allograft dysfunction in heart transplant recipients

Background: Myocardial perfusion gated single photon emission computed tomography (SPECT) can be used for non-invasive detection of coronary artery stenosis and cardiac allograft vasculopathy (CAV), which is a crucial factor for the long-term survival of heart transplant (HTx) recipients. A frequently observed finding in myocardial perfusion imaging of patients after HTx is inhomogeneous myocardial perfusion. This finding is not associated with epicardial CAV, but its prognostic relevance is unclear so far. We therefore evaluated the prognosis of patients with homogeneous versus inhomogeneous myocardial stress perfusion.

Methods: One hundred four HTx patients (mean 3.6 ± 2.9 years after HTx) without significant stress-induced ischemia (summed stress score ≤3) in gated SPECT and without CAV were included. Myocardial stress perfusion was visually assessed as homogeneous, moderately, or severely inhomogeneous. The mean follow-up period after SPECT was 9.4 ± 3.1 years. End points were the diagnosis of CAV, major cardiac events (MACE) or death, and the development of allograft dysfunction (left ventricular ejection fraction, LVEF <45 %).

Results: Of all HTx patients, 24 % enrolled in this study (n = 25) presented with inhomogeneous myocardial perfusion. Compared to the patients with homogeneous perfusion, these patients were at higher risk for developing allograft dysfunction (multivariate hazard ratio, HR = 5.59). As to the development of CAV, the occurrence of MACE, or death, no statistical differences were observed between patients with homogenous and inhomogeneous perfusion. There was no correlation between myocardial perfusion pattern and prior cardiac allograft rejections.

Conclusions: Inhomogeneous myocardial stress perfusion in SPECT studies predicts a higher risk for future development of allograft dysfunction in HTx patients (LVEF <45 %) but is not associated with future CAV, MACE, or overall survival.