Global and segmental absolute stress myocardial blood flow in prediction of cardiac events: [ 15 O] water positron emission tomography study.

Purpose: We evaluated the value of reduced global and segmental absolute stress myocardial blood flow (sMBF) quantified by [ ¹⁵ O] water positron emission tomography (PET) for predicting cardiac events in patients with suspected obstructive coronary artery disease (CAD).
Methods: Global and segmental sMBF during adenosine stress were retrospectively quantified in 530 symptomatic patients who underwent [ ¹⁵ O] water PET for evaluation of coronary stenosis detected by coronary computed tomography angiography.
Results: Cardiovascular death, myocardial infarction, or unstable angina occurred in 28 (5.3%) patients at a 4-year follow-up. Reduced global sMBF was associated with events (area under the receiver operating characteristic curve 0.622, 95% confidence interval (95% CI) 0.538-0.707, p = 0.006). Reduced global sMBF (< 2.2 ml/g/min) was found in 22.8%, preserved global sMBF despite segmentally reduced sMBF in 35.3%, and normal sMBF in 41.9% of patients. Compared with normal sMBF, reduced global sMBF was associated with the highest risk of events (adjusted hazard ratio (HR) 6.970, 95% CI 2.271-21.396, p = 0.001), whereas segmentally reduced sMBF combined with preserved global MBF predicted an intermediate risk (adjusted HR 3.251, 95% CI 1.030-10.257, p = 0.044). The addition of global or segmental reduction of sMBF to clinical risk factors improved risk prediction (net reclassification index 0.498, 95% CI 0.118-0.879, p = 0.010, and 0.583, 95% CI 0.203-0.963, p = 0.002, respectively).
Conclusion: In symptomatic patients evaluated for suspected obstructive CAD, reduced global sMBF by [ ¹⁵ O] water PET identifies those at the highest risk of adverse cardiac events, whereas segmental reduction of sMBF with preserved global sMBF is associated with an intermediate event risk.