CATCH-AF Score
(2026)Objective
To develop and validate a simple, clinically applicable tool for stratifying early and long-term atrial fibrillation risk after embolic stroke of undetermined source
Study Summary
• High-risk patients (≥5 points) had a 19-fold higher hazard of AF detection versus low-risk, with an AUC of 0.85.
• The score remained stable over 4.5 years of follow-up and across 7 centres in internal-external cross-validation.
Intervention
Observational cohort study with systematic ICM monitoring to detect atrial fibrillation after ESUS
Inclusion Criteria
Consecutive ESUS patients who received implantable cardiac monitors at 7 participating centres
Study Design
Arms: Single observational cohort with ICM monitoring, development and validation via internal-external cross-validation across 7 centres
Patients per Arm: 543 total patients
Outcome
Bottom Line
In 543 ESUS patients monitored with ICMs, the CATCH-AF score (range 0-9) based on age, coronary artery disease, heart failure, and prior TIA/stroke stratified AF risk with excellent discrimination (AUC 0.85) that remained stable over 4.7 years. High-risk patients (≥5 points, 17.1% of the cohort) had a 19-fold higher hazard of AF detection than low-risk patients and lost 918 more AF-free days. The score supports targeted and cost-effective rhythm monitoring after ESUS but requires external validation before widespread clinical adoption.
Major Points
- First prediction score specifically designed for AF detection in ESUS patients with long-term ICM monitoring. Addresses a key clinical gap: which ESUS patients benefit most from prolonged cardiac monitoring.
- 543 consecutive ESUS patients across 7 stroke centres (UK and Italy, 2021-2024), with 1558.5 patient-years of ICM follow-up (median 1104 days, IQR 695-1454.5). 118 patients (22%) developed new AF during follow-up.
- CATCH-AF components derived via LASSO-penalized Cox regression. Age: <60 years=0, 60-69=1, 70-79=2, ≥80=3; Coronary artery disease=2, Previous TIA/Stroke=2, Congestive Heart Failure=2. Total range 0-9.
- Discrimination: AUC 0.85 (95% CI 0.82-0.89) overall. Time-dependent AUC values actually INCREASED over time: 0.849 at 6 months, 0.844 at 12 months, 0.867 at 24 months, 0.872 at 36 months, 0.858 at 1710 days (~4.7 years) — performance did not decline.
- Risk stratification: Low risk (0-2 points) — 226 patients (41.6%), <10% AF at 1710 days; Medium risk (3-4 points) — 224 patients (41.3%), ~20% AF plateau at 3 years, HR 6.1 (95% CI 3.0-12.4, p<0.001) vs low risk; High risk (≥5 points) — 93 patients (17.1%), approaching 60% AF at long-term follow-up, HR 19.2 (95% CI 9.4-39.4, p<0.001) vs low risk.
- RMST analyses quantified absolute disease burden: high-risk patients lost 918 fewer AF-free days vs low-risk; 614 fewer days vs medium-risk; medium-risk lost 305 fewer AF-free days vs low-risk (all p<0.001).
- Internal validation via 10-fold cross-validation and internal-external cross-validation across the 7 participating centres demonstrated consistent discrimination and calibration across geographically distinct sites.
- Key clinical insight: LASSO regression shrank CHA2DS2-VASc, hypertension, diabetes, and sex to zero — they were NOT independent predictors once age, coronary artery disease, heart failure, and prior stroke were in the model.
- Methodological innovation vs prior scores (HAVOC, STAF, Brown ESUS-AF, AF-ESUS, ACTEL, Decryptoring): time-dependent ROC curves and restricted mean survival time (RMST) analysis provide longitudinal predictive performance and absolute time-based quantification of risk, respectively.
- ICM device used: Reveal LINQ (Medtronic Inc, Minneapolis, MN, USA). Study conducted per STROBE guidelines.
Study Design
- Study Type
- Retrospective, multicentre, observational cohort
- Randomization
- No
- Blinding
- Not applicable (observational)
- Sample Size
- 543
- Follow-up
- Median 1104 days (1558.5 patient-years)
- Centers
- 7
- Countries
- United Kingdom, Italy
Primary Outcome
Definition: New-onset atrial fibrillation detected during ICM follow-up (AF defined as irregular heart rhythm without detectable P waves lasting >30 seconds)
| Control | Intervention | HR/OR | P-value |
|---|---|---|---|
| - | - | - | <0.001 for all pairwise hazard comparisons |
Limitations & Criticisms
- Retrospective design — inherent risk of selection and information bias despite consecutive enrollment from prospective registries.
- Moderate sample size (N=543) limits power for rare subgroup analyses.
- Cohort limited to UK and Italy — external generalizability to non-European populations is unknown.
- The score has NOT been validated in a fully independent external cohort. Internal-external cross-validation across participating centres represents an intermediate strategy but does not replace true external validation.
- No head-to-head comparison with existing AF prediction scores (HAVOC, STAF, AF-ESUS, Brown ESUS-AF, ACTEL, Decryptoring) in the same cohort.
- ICM monitoring protocols may vary across centres despite standardized device (Reveal LINQ).
- Follow-up duration (median 1104 days, max 4.7 years) may be insufficient to refine long-term predictive accuracy beyond 5 years.
- The score was developed and validated exclusively in ESUS patients systematically monitored with ICMs — applicability to non-ICM monitoring modalities is uncertain.
- Residual confounding from unmeasured factors cannot be excluded despite comprehensive adjustment for clinical covariates.
Citation
D'Anna L, et al. Int J Stroke. 2026. doi:10.1177/17474930261428118.