1. In this prospective cohort study, left atrial reservoir and conduit strain were linearly associated with risk of first ischemic stroke in patients without atrial fibrillation.
2. Stroke prediction using CHA2DS2-VASc variables and left atrial reservoir had lower error compared to models that included left atrial conduit strain, contractile strain, or left atrial volume index (LAVI).
Evidence Rating Level: 2 (Good)
Study Rundown: Stroke can be the first clinical manifestation of atrial myopathy before the onset or detection of atrial fibrillation. Changes in atrial mechanical function and size could precede cardiac thromboembolic events and serve as predictive biomarkers of stroke in people without prior atrial fibrillation or ischemic stroke. This prospective cohort study used data from the Atherosclerosis Risk in Communities (ARIC) study to evaluate the association of measures of left atrial mechanical function (reservoir, conduit, and contractile strain) and size (LAVI) with ischemic stroke among patients without prior atrial fibrillation or ischemic stroke and to determine whether left atrial measures could improve ischemic stroke prediction in combination with the CHA2DS2-VASc score. Patients were followed for a mean time of 6.6 years. Left atrial reservoir and conduit strain were linearly associated with ischemic stroke. The ischemic stroke prediction model that combined the CHA2DS2-VASc variables and left atrial reservoir improved risk classification and reduced prediction error of patients who developed stroke within five years, as compared to the CHA2DS2-VASc variables alone or in combination with other atrial mechanical function and size measures. In the decision curve analysis, the CHA2DS2-VASc and left atrial reservoir model resulted in the greatest predicted net benefit. As a limitation, 20% of participants could not be contacted at the end of the study. Subclinical atrial fibrillation also could not be accounted for, as atrial fibrillation was identified primarily from hospital discharge records or death certificates.
In-Depth [prospective cohort study]: This prospective cohort study used data from the ARIC study to evaluate the association of measures of left atrial mechanical function (reservoir, conduit, and contractile strain) and size (LAVI) with ischemic stroke among people without prior atrial fibrillation or ischemic stroke. Participant data (n=4,917) was retrieved from visit five to the end of the ARIC study after excluding participants with missing measures of left atrial mechanical function and size, participants who were not White or Black due to small sample size, and participants with prevalent atrial fibrillation and stroke. Participants were followed for a mean of 6.6 years (standard deviation, 1.8). The contact rate with participants at the end of the study was 81%, though only 4.3% of participants had incomplete follow-up data owing to ARIC surveillance of hospital and death certificate data. Left atrial reservoir and conduit strain were linearly associated with ischemic stroke. The association of lower left atrial reservoir strain with ischemic stroke remained significant after adjustment for left atrial size, race-study center, medication use, incident atrial fibrillation or anticoagulation use, and potential bias introduced by nonattendance at visit five. The cumulative incidences of ischemic stroke in the lowest and highest quintiles of left atrial reservoir were 2.99% (95% Confidence Interval [CI], 1.89% to 4.09%) and 1.42% (CI, 0.64% to 2.20%), respectively. The ischemic stroke prediction model that combined left atrial reservoir strain and CHA2DS2-VASc variables yielded the lowest prediction error. Compared to the model with CHA2DS2-VASc variables alone, the new model reclassified 11.6% and 2% of participants who developed stroke within five years correctly and incorrectly, respectively. For participants who did not develop stroke at five years, the new model reclassified 12.2% and 12.7% correctly and incorrectly, respectively, compared to the model with CHA2DS2-VASc variables alone. In summary, for patients without atrial fibrillation or prior stroke, lower left atrial reservoir strain is independently associated with ischemic stroke and could inform updated prediction models.
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