Left atrial strain predicts subclinical atrial fibrillation detected by long-term continuous rhythm monitoring in elderly high-risk individuals

Abstract

Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): he Innovation Fund Denmark (grant no.: 12-135225), The Research Foundation for the Capital Region of Denmark, The Danish Heart Foundation (grant no.: 11-04-R83-A3363-22625 and 18-R125-A8534-22083), Aalborg University Talent Management Programme, Arvid Nilssons Fond, Skibsreder Per Henriksen, R. og Hustrus Fond, and Medtronic Background Left atrial (LA) speckle tracking is a novel technique that provides detailed information on atrial function. Its utility for predicting subclinical atrial fibrillation (SCAF) is, however, not well-established. Purpose To investigate whether LA speckle tracking measures are associated with SCAF as detected by long-term continuous rhythm monitoring. Methods This was an echocardiographic substudy of a randomized controlled clinical trial that enrolled elderly individuals (≥70 years) with a CHADS2-score≥2 to either no intervention or implantation of a loop recorder (Reveal LINQ) to detect SCAF (≥6 minutes). A subset of the participants receiving a loop recorder was included in this analysis. An echocardiographic examination was performed, which included conventional measurements and LA speckle tracking. LA speckle tracking allowed for assessment of reservoir, conduit, and contraction strain. Multivariable proportional hazards Cox regression was applied to adjust for the clinical risk score (CHARGE-AF) and net reclassification index (NRI) was used to assess prognostic improvement of this score. Incidence rate curves were constructed using Poisson models. Results Overall, 976 participants were eligible for analysis. Median follow-up time was 3 years (interquartile range: 1.7-4.0 years), during which 284 (29%) were diagnosed with SCAF. The mean age was 74 years, 56% were male, median CHA2DS2-VASc-score was 4. A dilated LA (LA volume≥34ml/m2) was observed in 152 (16%). LA speckle tracking revealed that both LA reservoir strain and contraction strain were univariable predictors of SCAF (HR = 1.05 (1.03-1.06) and HR = 1.07 (1.05-1.10), p < 0.001, per 1% decrease), such that decreasing reservoir and contraction strain were linearly associated with an increased risk of SCAF (figure). LA conduit strain was not a predictor of SCAF. These findings were unchanged after adjusting for the CHARGE-AF score, and both LA strain measures significantly improved the NRI when added to the CHARGE-AF score by 23% and 33%, respectively. Even in participants with normal LA size, both reservoir and contraction strain were independent predictors of SCAF after multivariable adjustment (HR = 1.03 (1.01-1.05), p = 0.001 and HR = 1.06 (1.04-1.09), p < 0.001, per 1% decrease). Conclusion Decreasing left atrial reservoir and contraction strain are independently associated with an increased risk of SCAF as detected by long-term continuous monitoring and provide incremental prognostic value in addition to clinical risk score. Abstract Figure.

Response by Olsen et al to Letter Regarding Article, “Left Atrial Strain Predicts Subclinical Atrial Fibrillation Detected by Long-Term Continuous Monitoring in Elderly High-Risk Individuals”

“…2 It is indeed possible that RA strain may be more valuable than RA size, similar to what has been observed for the left atrium. 1 RA reservoir strain seems a reliable indicator of elevated RA pressure 3 and, contrary to RA size, has been shown to be significantly associated with RA fibrosis. 2 Additionally, international societies have proposed practical guidelines for benchmarking RA strain assessment.…”

“…We appreciate the interest shown by Tomaselli et al regarding our study on left atrial strain measures as predictors of subclinical atrial fibrillation (AF) in the LOOP study (Atrial Fibrillation Detected by Continuous Electrocardiogram Monitoring Using Implantable Loop Recorder to Prevent Stroke in High-risk Individuals). 1…”

Letter by Tomaselli et al Regarding Article, “Left Atrial Strain Predicts Subclinical Atrial Fibrillation Detected by Long-Term Continuous Monitoring in Elderly High-Risk Individuals”

“…We have read the article by Olsen et al 1 with great interest. The study investigated the use of left atrial (LA) strain to identify high-risk elderly subjects who are at risk of subclinical atrial fibrillation (AF).…”

Straining the Limits: Atrial Imaging to Predict Subclinical Atrial Fibrillation

“…In this substudy of implantable loop group participants, Olsen et al 6 assessed left atrial function, a marker of atrial cardiopathy, using echocardiography and left atrial speckle tracing, a time-efficient, and consistently reproducible technique for dynamically evaluating the myocardium. 7 Investigators performed speckle tracing by manually contouring the left atrial wall in the apical 4-chamber and 2-chamber views and defined 3 types of strain: (1) reservoir (peak positive strain value), (2) contraction (peak value at the onset of the P wave), and (3) conduit (the arithmetic difference between reservoir and contraction strain).…”