Impaired left atrial strain is associated with acute ischemic stroke in patients without atrial fibrillation

Background Cryptogenic stroke, defined as a stroke with an unknown cause, poses a significant clinical challenge in cardiology and neurology. Left atrial (LA) dysfunction, as measured by left atrial strain (LAS), may identify patients who are at high risk for acute ischemic stroke (AIS), even if they do not have documented atrial fibrillation (AF). Methods This retrospective, cross-sectional and cohort study (known as the ASSISTANT Study) was conducted at a single, tertiary-care referral center. The study included patients who tested positive on the Face Arm Speech Test (FAST) and who did not have high-risk stroke mechanisms. These patients presented acutely and underwent a transthoracic echocardiogram. Speckle-tracking echocardiography was used to measure LAS in three phases: reservoir (LASr), conduit (LAScd), and contractile (LASct). The associations of LAS with imaging-confirmed acute ischemic stroke (AIS) at presentation and incident AIS during follow-up were evaluated using multivariable logistic and Cox regression analyses, respectively. Results Among the 415 patients (251 cases and 164 controls), LASr and LAScd were both independently associated with AIS at presentation [OR per 5% increase: 0.789 (95% CI, 0.674–0.920) and 0.573 (95% CI, 0.450–0.718), respectively]. During a median follow-up of 3.59 years, 31 patients developed incident AIS. The incidence of AIS increased as the tertiles of LASr ( P trend = 0.021) and LAScd ( P trend < 0.001) worsened. Only LAScd remained independently associated with incident AIS [HR per 5% increase: 0.682 (95% CI, 0.478–0.953)]. Conclusion Impaired LAScd is independently associated with prevalent and incident AIS in patients without identified high-risk stroke mechanisms. Prospective studies are needed to determine whether LAScd can guide risk stratification and preventive strategies in this patient population. Trial Registration ClinicalTrials.gov (NCT07102693).