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 (Rb) 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 Rb PET MPI.

METHODS

A total of 9878 consecutive patients with LVEF ≥40% undergoing rest/pharmacologic stress Rb 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 Rb PET MPI offers independent prognostic value in patients with both normal and abnormal perfusion independent of other risk factors in patients with LVEF ≥40%.