Left atrial reservoir strain predicts ischemic stroke after coronary artery bypass grafting independent of postoperative atrial fibrillation

Background

Patients undergoing coronary artery bypass grafting (CABG) surgery face an elevated long-term risk of ischemic stroke.

Left atrial (LA) mechanics including LA strain are known to predict both stroke and atrial fibrillation in other populations. Evidence is conflicting with regards to the clinical significance of postoperative atrial fibrillation (POAF) and its role in the association between LA mechanics and ischemic stroke is unclear.

Purpose

The aim of the study was to investigate the association between LA reservoir strain and long-term ischemic stroke in patients undergoing CABG surgery and whether the presence of POAF modified this relationship.

Methods

Patients undergoing isolated CABG were included from 2006–2011 as part of a retrospective cohort study. Echocardiography was performed prior to surgery. We included patients with available LA reservoir strain measurements, while patients with known atrial fibrillation and moderate to severe valvular disease were excluded. The primary endpoint was ischemic stroke. The association between LA reservoir strain and ischemic stroke was investigated in uni- and multivariable Cox proportional hazards regression models including adjustment for POAF. Poisson regression was used to create a restricted cubic spline model of the continuous association between LA reservoir strain and risk of ischemic stroke.

Results

We included 542 patients in the analysis. Mean age was 67.3±8.9 years, 89 (16.4%) were female, and median EuroSCORE II was 1.31 (IQR 0.93–1.96). Patients with LA reservoir strain <27.2% (median) were older, more likely to have diabetes, and had a higher EuroSCORE II.

In total, 96 patients (17.7%) developed POAF. During a median follow-up period of 3.7 years (IQR 2.7–4.8 years), 21 (3.9%) patients experienced ischemic stroke. In univariable modeling, LA reservoir strain was significantly associated with ischemic stroke (HR 1.10 (95% CI 1.03–1.18, p=0.003) per 1% absolute decrease). After adjustment for EuroSCORE II, LA volume index (LAVi) and prior stroke, LA reservoir strain remained a significant predictor of ischemic stroke (HR 1.09 (95% CI 1.02–1.17, p=0.011) per 1% absolute decrease and HR 4.24 (95% CI 1.37–13.10, p=0.012) for < vs. >median). Adding POAF as a covariate did not alter the significance of LA reservoir strain in the model. In addition, POAF did not modify the association between LA reservoir strain and POAF (p for interaction = 0.07). The association between LA reservoir strain and ischemic stroke persisted in multiple sensitivity analyses including restricting the analysis to patients with normal left atrial volumes (LAVi <34 ml/m2), patients without POAF, and when excluding patients who developed atrial fibrillation during follow-up.

Conclusion

In patients undergoing CABG, LA reservoir strain was an independent long-term predictor of ischemic stroke. The predictive value of LA reservoir strain was unaffected by the presence of POAF.

Funding Acknowledgement

Type of funding sources: None.

Cost-effectiveness of adding a non-invasive acoustic rule-out test in the evaluation of patients with symptoms suggestive of coronary artery disease: rationale and design of the prospective, randomised, controlled, parallel-group multicenter FILTER-SCAD trial

INTRODUCTION

Most patients with symptoms suggestive of chronic coronary syndrome (CCS) have no obstructive coronary artery disease (CAD) and better selection of patients to be referred for diagnostic tests is needed. The CAD-score is a non-invasive acoustic measure that, when added to pretest probability of CAD, has shown good rule-out capabilities. We aimed to test whether implementation of CAD-score in clinical practice reduces the use of diagnostic tests without increasing major adverse cardiac events (MACE) rates in patients with suspected CCS.

METHODS AND ANALYSIS

FILTER-SCAD is a randomised, controlled, multicenter trial aiming to include 2000 subjects aged ≥30 years without known CAD referred for outpatient assessment for symptoms suggestive of CCS. Subjects are randomised 1:1 to either the control group: standard diagnostic examination (SDE) according to the current guidelines, or the intervention group: SDE plus a CAD-score. The subjects are followed for 12 months for the primary endpoint of cumulative number of diagnostic tests and a safety endpoint (MACE). Angina symptoms, quality of life and risk factor modification will be assessed with questionnaires at baseline, 3 months and 12 months after randomisation. The study is powered to detect superiority in terms of a reduction of ≥15% in the primary endpoint between the two groups with a power of 80%, and non-inferiority on the secondary endpoint with a power of 90%. The significance level is 0.05. The non-inferiority margin is set to 1.5%. Randomisation began on October 2019. Follow-up is planned to be completed by December 2022.

ETHICS AND DISSEMINATION

This study has been approved by the Danish Medical Agency (2019024326), Danish National Committee on Health Research Ethics (H-19012579) and Swedish Ethical Review Authority (Dnr 2019-04252). All patients participating in the study will sign an informed consent. All study results will be attempted to be published as soon as possible.

TRIAL REGISTRATION NUMBER

NCT04121949; Pre-results.