Ultra-Early Continuous ECG Monitoring for Silent Atrial Fibrillation Diagnosis in Cryptogenic Stroke - The CRIPTOFAST Randomized Controlled Trial

Q: What problem does the CRIPTOFAST trial address?

It addresses whether early, continuous ECG monitoring with an internal loop recorder improves diagnosis of silent paroxysmal atrial fibrillation after cryptogenic stroke, compared with standard care.

Q: How did the trial detect silent atrial fibrillation episodes?

Patients with cryptogenic stroke were randomized to receive an early ILR or standard care, and the ILR group was used to detect silent PAF episodes during follow-up.

Q: Which left atrium features were used to identify patients more likely to benefit?

Subtle left atrium anomalies were used in a pre-specified subgroup analysis, including LA dilatation, reduced maximum systolic global longitudinal strain, reduced atrial contraction strain, and reduced atrial ejection fraction.

Sep 28, 2026

Uploaded by Jasmine

Cryptogenic strokes account for about one third of stroke-unit admissions, and silent paroxysmal atrial fibrillation (PAF) is considered a frequent underlying cause. Guidelines remain uncertain about whether internal loop recorder (ILR) use after cryptogenic stroke improves detection. This randomized, controlled, parallel-arm open-label trial evaluated early ILR versus standard care and assessed clinical and subtle left atrium ultrasound markers to identify patients most likely to benefit.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages11

Reading Time28 min

AccessFree to download

Abstract

Background

Methods

Results

Conclusions

Introduction

European Journal of Neurology ORIGINAL ARTICLE OPEN ACCESS Ultra-Early Continuous ECG Monitoring for Silent Atrial Fibrillation Diagnosis in Cryptogenic Stroke: The CRIPTOFAST Randomized Controlled Trial E. Vallès1,2 | A. B. Garcia1 | E. Giralt-Steinhauer1,2 | M. Ble1,2 | J. I. Jiménez1,2 | B. Casteigt1 | C. E. González-Matos1 | E. Cuadrado-Godia1,2 | A. González1 | F. Zaraket1 | O. Rodriguez1 | G. Guelfand1 | M. A. Guijo1 | M. Cainzos-Achirica1,2 1Hospital del Mar and Hospital del Mar Research Institute, Barcelona, Spain | 2Universitat Pompeu Fabra, Barcelona, Spain Correspondence: E. Vallès ([ermengolvalles@mac.com](ermengolvalles@mac.com)) Received: 25 July 2025 | Revised: 11 November 2025 | Accepted: 17 December 2025 Keywords: atrial fibrillation | cryptogenic stroke | internal loop recorder | left atrium | strain ABSTRACT Background: Cryptogenic strokes (CS) represent one third of admissions for stroke. Silent paroxysmal atrial fibrillation (PAF) is the underlying cause of a significant proportion of cases. The use of internal loop recorders (ILR) after CS has shown controversial results, remaining unclear in guidelines. Subtle ultrasound left atrium (LA) anomalies may help select patients more prone to suffer from silent PAF who can benefit from an ILR. Methods: Randomized, controlled, parallel-arm, open-label trial of patients with CS. We evaluated the efficacy of early ILR for detection of silent PAF episodes compared to standard care. Clinical/ultrasound predictors of PAF were studied. The presence of subtle LA anomalies (any of: LA dilatation, maximum systolic global longitudinal strain < 21%, atrial contraction strain < 13%, atrial ejection fraction < 55%) was used in a pre-specified subgroup analysis. Results: Fifty-nine CS patients were included (52.5% to ILR and 47.5% to standard care) . There were no statistically significant differences among groups regarding baseline characteristics. Median follow-up was 377 days. The diagnosis of silent PAF was made in 43.3% in the ILR group compared to 7.1% in the control group (HR 7.47, 95% CI 1.68–31.19, p = 0.008) . Most PAF events were detected in the 100 days following ILR implantation. In patients with normal LA, PAF was observed in 23% versus 7%, while in patients with abnormal LA, PAF was diagnosed in 58.8% versus 7.7% . Conclusions: An ILR implanted early after CS improves the detection of PAF compared to standard care. Individuals with abnormal LA features may benefit the most from ILR. 1 | Introduction Cryptogenic stroke (CS) is a type of stroke for which the etiology cannot be determined after a comprehensive evaluation. CS represents one third of admissions to stroke units in industrialized countries [1] . In these patients, current guidelines recommend using single antiplatelet therapy as a long-term treatment. However, silent paroxysmal atrial fibrillation (PAF) is believed to be the underlying cause of a significant proportion of CS episodes [2, 3], specifically of ESUS episodes (embolic stroke of undetermined source) [4] . In the presence of PAF, antiplatelet therapy is less effective preventing strokes than oral | Abbreviations: ACS, atrial contraction strain; CS, cryptogenic stroke; CT, computed tomography; ECG, electrocardiogram; GM, glomerular filtration; ILR, implantable loop recorder; LA, left atrium; LAEF, left atrium ejection fraction; NSAT, non-sustained atrial tachycardia; OAC, oral anticoagulation; PACS, peak atrial contraction strain; PAF, paroxysmal atrial fibrillation; PALS, peak atrial longitudinal strain; SAT, supra-aortic trucks; SHD, structural heart disease. | | --- | | This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.
© 2025 The Author(s). European Journal of Neurology p

FAQs

What problem does the CRIPTOFAST trial address?

It addresses whether early, continuous ECG monitoring with an internal loop recorder improves diagnosis of silent paroxysmal atrial fibrillation after cryptogenic stroke, compared with standard care.

How did the trial detect silent atrial fibrillation episodes?

Patients with cryptogenic stroke were randomized to receive an early ILR or standard care, and the ILR group was used to detect silent PAF episodes during follow-up.

Which left atrium features were used to identify patients more likely to benefit?

Subtle left atrium anomalies were used in a pre-specified subgroup analysis, including LA dilatation, reduced maximum systolic global longitudinal strain, reduced atrial contraction strain, and reduced atrial ejection fraction.

Sep 28, 2026

Uploaded by Jasmine