Heart Size Difference Drives Sex‐Specific Response to Cardiac Resynchronization Therapy: A Post Hoc Analysis of the MORE‐MPP CRT Trial
Bibliographic record
Abstract
Background Studies have reported that female sex predicts superior cardiac resynchronization therapy (CRT) response. One theory is that this association is related to smaller female heart size, thus increased relative dyssynchrony at a given QRS duration (QRSd). Our objective was to investigate the mechanisms of sex‐specific CRT response relating to heart size, relative dyssynchrony, cardiomyopathy type, QRS morphology, and other patient characteristics. Methods and Results This is a post hoc analysis of the MORE‐CRT MPP (More Response on Cardiac Resynchronization Therapy with Multipoint Pacing) trial (n=3739, 28% women), with a subgroup analysis of patients with nonischemic cardiomyopathy and left bundle‐branch block (n=1308, 41% women) to control for confounding characteristics. A multivariable analysis examined predictors of response to 6 months of conventional CRT, including sex and relative dyssynchrony, measured by QRSd/left ventricular end‐diastolic volume (LVEDV). Women had a higher CRT response rate than men (70.1% versus 56.8%, P <0.0001). In subgroup analysis, regression analysis of the nonischemic cardiomyopathy left bundle‐branch block subgroup identified QRSd/LVEDV, but not sex, as a modifier of CRT response ( P <0.0039). QRSd/LVEDV was significantly higher in women (0.919) versus men (0.708, P <0.001). CRT response was 78% for female patients with QRSd/LVEDV greater than the median value, compared with 68% with QRSd/LVEDV less than the median value ( P =0.012). The association between CRT response and QRSd/LVEDV was strongest at QRSd <150 ms. Conclusions In the nonischemic cardiomyopathy left bundle‐branch block population, increased relative dyssynchrony in women, who have smaller heart sizes than their male counterparts, is a driver of sex‐specific CRT response, particularly at QRSd <150 ms. Women may benefit from CRT at a QRSd <130 ms, opening the debate on whether sex‐specific QRSd cutoffs or QRS/LVEDV measurement should be incorporated into clinical guidelines.
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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 | 0.004 | 0.004 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.003 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".