Electrophysiology And Arrhythmia Scores

MB-LATER Score Calculator – Late AF Recurrence After Ablation

Clinical calculation support · Verify results before clinical use

Clinical score assessment

Enter the patient's pre-ablation characteristics and post-ablation early recurrence status.

—Score / 6

Male sex

Male sex before the index ablation procedure.

Male

Female

Bundle branch block

Pre-procedural ECG showing left or right bundle branch block.

Present

Absent

Left atrial anteroposterior diameter

Pre-ablation transthoracic echocardiographic left atrial diameter. Score threshold: ≥47 mm.

Left atrial diameter (mm)

Use the anteroposterior diameter in millimetres.

Type of atrial fibrillation

Clinical AF type before the ablation procedure.

Paroxysmal AF 0

Persistent AF 1

Long-standing persistent AF 2

Original definitions: paroxysmal AF terminates spontaneously within 7 days; persistent AF lasts ≥7 days or requires cardioversion; long-standing persistent AF lasts >1 year.

Early recurrence of atrial tachyarrhythmia

During the original 3-month post-ablation blanking period, any documented AF, atrial tachycardia, or typical atrial flutter lasting >30 seconds.

Yes

Eligibility for the original MB-LATER target population

The score was derived for patients who remained free of late recurrence between months 3 and 12 and were assessed beyond 12 months after the last ablation.

Has at least 12 months elapsed since the most recent AF ablation?

Was the patient free from late atrial tachyarrhythmia recurrence between months 3 and 12 after the last ablation?

—MB-LATER

Assessment result

Complete all required inputs

The score will be calculated when all clinical variables and eligibility items are entered.

Clinical interpretation MB-LATER is a prognostic score for very late recurrence after AF ablation; it is not a diagnostic test and does not estimate an individual absolute probability of recurrence.

Score breakdown

Component	Finding	Points

Do not use this score alone to determine rhythm-control treatment, repeat ablation, or anticoagulation decisions.

About the MB-LATER Score

The MB-LATER score (“May-Be-LATER”) was developed to identify patients at increased risk of very late atrial tachyarrhythmia recurrence after catheter ablation for atrial fibrillation. In the original study, very late recurrence was defined as recurrence occurring more than 12 months after ablation.

The original derivation cohort consisted of 133 patients who were free of late recurrence during the first post-ablation year. The score includes five clinical components and ranges from 0 to 6 points.

Variables and points

Component	Criterion	Points
Male sex	Male	1
Bundle branch block	Pre-procedural BBB (left or right)	1
Left atrial diameter	Anteroposterior diameter ≥47 mm	1
AF type	Paroxysmal / Persistent / Long-standing persistent	0 / 1 / 2
Early recurrence	AF/AT/typical AFL >30 s during original 3-month blanking period	1

Interpreting the score

The original derivation study reported the best cut-off at ≥2 points (sensitivity 75.0%, specificity 72.6%, positive predictive value 32.6%, and negative predictive value 94.3%). This is a study-derived discrimination threshold, not a calibrated absolute-risk category.

An external validation cohort reported a different optimal cut-off (>2 points), with AUC 0.62, sensitivity 42.9%, and specificity 74.2%. The difference should be kept in mind; neither threshold should be interpreted as a universally established treatment boundary.

Important timing distinction

The MB-LATER score uses the original study's 3-month blanking-period definition for its early-recurrence component. The 2024 international ablation consensus recommends an 8-week blanking period for clinical-trial outcome assessment. This newer consensus definition should not silently replace the original score variable when reproducing MB-LATER.

Evidence and limitations

In the original retrospective, single-centre derivation cohort, the score had an AUC of 0.782 (95% CI 0.684–0.880). Only 20 very late recurrence events occurred in the derivation cohort, and the exploratory validation sample was small (39 patients, with three events).

The first external validation study included 226 patients and found modest discrimination (AUC 0.62; 95% CI 0.54–0.69). A later independent cohort of 883 patients also found only modest predictive performance for 12-month recurrence (AUC 0.612).

Accordingly, the score can support risk communication and consideration of follow-up intensity, but should not be used as a stand-alone decision rule.

Clinical safeguards

Not intended for pre-ablation prediction.
Not designed to predict recurrence during months 3–12.
Interpret only in the context of the population and follow-up conditions in which it was developed.
Do not use MB-LATER to stop or continue oral anticoagulation; anticoagulation decisions should follow thromboembolic-risk guidance, irrespective of apparent ablation success.
Do not infer a numerical individual recurrence probability from the total score.

References

Mujović N, Marinković M, Marković N, et al. Prediction of very late arrhythmia recurrence after radiofrequency catheter ablation of atrial fibrillation: The MB-LATER clinical score. Scientific Reports. 2017;7:40828. doi:10.1038/srep40828

Potpara TS, Mujovic N, Sivasambu B, et al. Validation of the MB-LATER score for prediction of late recurrence after catheter-ablation of atrial fibrillation. International Journal of Cardiology. 2019;276:130–135. doi:10.1016/j.ijcard.2018.08.018

Filipovic K, Daniel S, Arian S, et al. Validation of seven risk scores in an independent cohort: the challenge of predicting recurrence after atrial fibrillation ablation. International Journal of Arrhythmia. 2022;23:29. doi:10.1186/s42444-022-00080-0

2024 EHRA/HRS/APHRS/LAHRS Expert Consensus Statement. 2024 consensus statement on catheter and surgical ablation of atrial fibrillation. Includes the updated 8-week blanking-period recommendation for clinical-trial outcome assessment. Official consensus publication

Clinical disclaimer: The MB-LATER score is an adjunctive prognostic instrument derived from observational data. It does not replace clinical assessment, ECG/rhythm monitoring, shared decision-making, or current guideline-based management. Its discrimination has been modest in external cohorts. Do not use the score as the sole basis for repeat ablation, antiarrhythmic drug decisions, or anticoagulation management.