Correspondence of Rb-82 PET stress regional myocardial asynchrony to stenosed arterial territories

Objectives: Global asynchrony of left ventricular (LV) contraction is most commonly assessed with Rb-82 gated PET by measuring phase bandwidth (BW). However, parameters to assess regional asynchrony, phase polar coordinate maps, are also generated. Our investigation was undertaken to determine if LV regions exhibiting worsening asynchrony with stress correspond to territories supplied by stenosed coronaries.

Methods: Data were retrospectively reviewed for 61 pts undergoing rest/regadenoson-stress Rb-82 gated PET for evaluation of potential coronary artery disease (CAD) who also had x-ray contrast coronary arteriography. LV phase contraction histograms and phase polar maps were examined, depicting the phase of contraction of all pixels. For left anterior descending (LAD), left circumflex (LCX) & and right coronary artery (RCA) territories the magnitude & extent of phase contraction polar maps being out of phase from expected contraction patterns referenced to a data base of normal subjects were scored on a 5-point scale (0 = “normal” to 4 = “markedly asynchronous extensive territory”). Coronary arteriograms were quantified at a core laboratory & arterial territories with 蠅 70% stenosis were considered abnormal.

Results: 13% (8/61) LAD, 23% (14/61) LCX & 23% (14/61) of RCA territories were stenosed by 蠅 70%. For global LV asynchrony, correlation with the number of stenosed vessels was strongest for stress BW (r = 0.52, p<0.0001), rather than for rest phase BW (r = 0.30, p=0.02) or stress-rest change of BW values (r = 0.34, p=0.007). Using regional asynchrony scores for all coronary territories, ROC analysis indicated that accuracy for identifying territories with coronary stenoses was higher for stress regional phase scores than for rest or difference regional phase scores (ROC areas = 79±5%, 70±5%, & 66±5%, respectively). Stress regional phase scores were more accurate at identifying stenosed arteries for LAD than LCX or RCA territories (ROC areas = 92±7%, 75±8%, 75±8%, respectively). Phase regional score differences between stenosed & non-stenosed arteries were greater for LAD territories than for LCX or RCA territories (Table).

Conclusion: Regional rest & stress phase maps should be generated routinely in the evaluation of patients for potential coronary artery disease, as abnormal regional phase indicates a high likelihood of CAD, particularly in LAD territories. Research Support: grant from Astellas, Inc