Predictive value of left atrial strain for early detection of atrial fibrillation after acute ischemic stroke

Background

Atrial fibrillation detected after stroke (AFDAS) occurs in up to 24% of patients with acute ischemic stroke and has major implications for secondary prevention and long-term antithrombotic therapy. Left atrial (LA) mechanical dysfunction, a marker of atrial cardiomyopathy, may precede overt atrial fibrillation (AF); but the predictive value of LA strain for early AFDAS remains uncertain .

Purpose

To evaluate the association between LA strain parameters and early AFDAS identified by continuous ambulatory rhythm monitoring following acute ischemic stroke.

Methods

In an observational cohort study, consecutive patients with acute ischemic stroke with no prior AF underwent 7-day continuous patch ECG monitoring. Transthoracic echocardiography with speckle-tracking analysis quantified LA reservoir (LASr), conduit (LAScd), and contraction strain (LASct). Associations with early AFDAS were assessed using group comparisons, receiver operating characteristic (ROC) analysis, and multivariable models adjusting for age and sex.

Results

Among 498 patients (63% male; mean age 65.7±12.8 years; mean NIHSS 3.5), early AFDAS was identified in 25 (5%). Patients with AFDAS were significantly older (76.0±10.5 vs. 65.2±12.7 years; p=<0.001), 52% were women, and had higher rates of hypertension and hyperlipidemia.

On univariated analysis, LASr and LASct were significantly impaired in AFDAS (LASr: 25.65±13.34% vs. 31.19±12.78%, p=0.036; LASct: −12.06±9.97% vs. −16.07±7.90%, p=0.015), Mean LASr was lower in the AFDAS group (25.65±13.34% vs 31.19±12.78%, p=0.036). Similarly, LASct was less negative (reflecting reduced contractile function) in AFDAS patients (−12.06±9.97% vs −16.07±7.90%, p=0.015). LA conduit strain (LAScd) was not associated with AFDAS (p=0.389). ROC analysis demonstrated modest but statistically significant discrimination for LASr (AUC 0.646; 95% CI 0.603–0.688; p=0.016) and LASct (AUC 0.641; 95% CI 0.597–0.683; p=0.021). ROC analysis identified an optimized LASr cut-off value of <19% for predicting AFDAS (AUC=0.654; 95% CI: 0.611–0.696; p=0.0028), sensitivity 48%, specificity 82.9%). LASct ≥−13.4% was also associated with AFDAS detection (p=0.0208). In multivariable analysis adjusting for age and sex, LASr <19% remained independently associated with early AFDAS (HR 3.53; 95% CI 1.52–8.23; p=0.0034).

Conclusions

Reduced LA reservoir and contraction strain are independently associated with early AFDAS after acute ischemic stroke. An LA strain below 19% may serve as a noninvasive marker of atrial cardiomyopathy to aid in identifying patients who may benefit from more intensive post-stroke rhythm monitoring.AFDAS TableAFDAS Figure