Prognostic utility of quantitative positron emission tomography in patients with prior coronary artery bypass grafting: incremental value of myocardial flow reserve and coronary vascular resistance
Bibliographic record
Abstract
Abstract Background In patients with prior coronary artery bypass grafting (CABG), the utility of quantitative positron emission tomography (PET) perfusion parameters remains unestablished. While quantitative PET overcomes the limitations of relative perfusion imaging in multivessel coronary artery disease by assessing myocardial blood flow (MBF), its prognostic relevance is less well explored. Purpose We sought to evaluate the prognostic value of PET-derived myocardial flow reserve (MFR) to assess epicardial coronary disease and coronary vascular resistance (CVR) for microvascular disease in CABG patients. Methods This retrospective study included consecutive patients undergoing Rubidium-82 PET myocardial perfusion imaging between May 2017 and November 2023. MFR was defined as stress/rest MBF, with a cut-off of 2.0 for impaired MFR. CVR was calculated as mean arterial pressure divided by stress MBF, with an optimal cut-off of 60 mmHg·min·g/mL determined by area under the curve analysis. The primary outcome was major adverse cardiovascular events (MACE), defined as a composite of all-cause mortality and nonfatal myocardial infarction. Associations were assessed using multivariable Cox proportional hazards models after adjusting for clinical variables and PET parameters. Results A total of 556 patients (median age 72 years, 79% male) were included. Over a median follow-up of 676 (482–1077) days, 71 patients (12.8%) experienced MACE. Patients with impaired MFR or CVR had significantly higher MACE rates (both p<0.001) (Figure 1). Stratifying by preserved or impaired MFR and CVR revealed significant differences in MACE incidence across the four combination groups (p<0.001) (Figure 2). Both MFR (<2.0) and CVR (≥60) independently predicted MACE, with adjusted hazard ratios of 3.204 (95% CI, 1.777–5.777; p<0.001) and 2.350 (95% CI, 1.308–4.223; p=0.004), respectively. Conclusions PET-derived MFR and CVR provide independent and incremental prognostic value, enhancing risk stratification beyond conventional perfusion and function parameters in CABG patients.Figure 1 Figure 2
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".