Abstract 14344: The Magnitude and Time Course of Stress Induced Left Ventricular Transient Ischemic Dilation: A CMR Perspective
Bibliographic record
Abstract
Background: Transient ischemic dilation (TID) of the left ventricle is used in nuclear myocardial stress perfusion imaging to identify global myocardial ischemia due to multi-vessel atherosclerosis. Although the isotope is injected at peak stress, nuclear stress images are obtained 20-30 minutes later to allow for hepatic clearance of isotope. Cardiac MRI myocardial stress perfusion imaging is performed at peak regadenoson effect. Given the superior spatial resolution of CMR, it also useful for accurate assessment of LV dimensions, both at rest and after stress. This prospective study was designed to assess the time course of peak regadenoson TID with direct measurement of LV dimensions and volumes using CMR. Methods: A standard CMR myocardial perfusion protocol was modified by adding a short axis SSFP imaging sequence at the level of the papillary muscle tips, just before the 1st pass perfusion study at peak regadenoson effect, and again 20-30 minutes later, after delayed enhancement imaging was completed. Parameters for this study included LV end-diastolic diameter (EDD) and slice volume (EDV), LV end-systolic diameter (ESD) and slice volume (ESV). TID was defined as an increase in end-diastolic diameter at stress compared to rest. An independent sample t-test was used to compare mean values. Results: Data was obtained from 181 consecutive patients undergoing CMR stress studies over a 6 month period. Stress induced LV dilation occurred in 61 patients, but not in 120. Of 61 patients with stress induced LV dilation, the mean slice EDV at rest was 18.24 mL3 and increased to 19.83 mL3 at stress (p<.05). At 20-30 minutes post regadenoson, mean slice volume remained non-significantly elevated at 18.84mL3 (p=.415) relative to the baseline slice EDV. Of the 120 patients without stress induced dilation, mean slice EDV decreased from 21.10 mL3 at rest to 19.65 mL3 at stress (p<.05). Mean slice volume remained non-significantly decreased at 20-30 minutes post stress (p=.188). Conclusions: These data suggest that maximum TID occurs at the time of peak regadenoson effect and attenuates to baseline over 20-30 minutes. Because of the inherent delay in obtaining myocardial stress perfusion images with a nuclear technique, CMR stress assessment of TID may be preferable.
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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 | 0.000 | 0.001 |
| 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) | 0.003 | 0.001 |
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".