Prognostic value of transient ischemic dilation on Rubidium-82 positron emission tomography myocardial perfusion imaging

Background: Transient ischemic dilation (TID) of the left ventricular (LV) cavity is considered a high-risk marker in patients with abnormal single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). Stress image acquisition with rubidium-82 (⁸²Rb) PET occurs at peak stress compared to 30-60 minutes post-stress with SPECT. We aimed to evaluate the prognostic value of TID in patients undergoing ⁸²Rb PET MPI.

Methods: A total of 9878 consecutive patients with LVEF ≥40% undergoing rest/pharmacologic stress ⁸²Rb PET MPI from 2010 to 2016 were followed for a median of 3.2 years. The primary clinical outcome of cardiac death was assessed after adjusting for pre-test risk, known coronary artery disease (CAD), resting left ventricular ejection fraction (LVEF), summed stress score (SSS), LVEF reserve (LVEF-R), myocardial blood flow reserve (MBFR), and early (90-day) revascularization. Pre-specified interactions between TID and SSS were included to assess potential differences in the prognostic value of TID in patients based on perfusion.

Results: The mean age of the cohort was 69.0 (11.7) years with 56.1% being female, 49.8% having known CAD, and 27.9% having abnormal perfusion (SSS>0). There were 451 cardiac deaths. Higher TID ratios were associated with higher risk of cardiac death, even after accounting for LVEF-R and MBFR (HR per .1 unit increase = 1.25 (1.11, 1.41), P < .001). This was seen in patients with both normal (HR for TID per .1 unit increase = 1.24 (95% CI: 1.01, 1.52), P = .04) and abnormal perfusion (HR for TID per .1 unit increase = 1.14 (95% CI: 1.02, 1.28), P = .03).

Conclusions: TID on rest/stress ⁸²Rb PET MPI offers independent prognostic value in patients with both normal and abnormal perfusion independent of other risk factors in patients with LVEF ≥40%.