Novel Echo Markers In Stroke Risk Stratification In AFib

The assessment of left atrial reservoir strain and P-wave to A’ duration on tissue Doppler imaging provides additional risk stratification for stroke after initial CHA₂DS₂-VASc scoring, according to a study published in the European Heart Journal, and may prove helpful in guiding decisions about anticoagulation for patients after the diagnosis of atrial fibrillation.

Currently, clinical practice guidelines recommend risk stratification of atrial fibrillation patients using the CHA₂DS₂-VASc to determine patients’ need for oral anticoagulation. In this study, Dr. Melissa Leung and her colleagues aimed to identify novel echocardiographic markers of left atrial function that may provide improved risk stratification to identify atrial fibrillation patients at increased risk for stroke who may benefit from anticoagulation.

Overall, 1361 patients were identified from a retrospective hospital-based registry of all patients who were referred for electrical cardioversion for atrial fibrillation to a tertiary referral center and had a baseline transthoracic echocardiogram between April 1995 and January 2015. Patients were followed by chart review for the occurrence of a composite endpoint of ischemic stroke or transient ischemic attack for a mean duration of approximately 8 years. P-wave to A’ duration on tissue Doppler imaging and left atrial reservoir strain were assessed for association with the occurrence of the composite endpoint.

Approximately 7% of patients (N=100) experienced the primary endpoint, and 93% (N=1261) did not. Patients who had a stroke were more likely to be older and to have hypertension, dyslipidemia, a history of stroke or transient ischemic attack, and a CHA₂DS₂-VASc score ≥ 2. Additionally, those who had a stroke were less likely to be treated with an anticoagulant at baseline. The incidence of stroke was higher in the first year following diagnosis when compared to the remaining follow-up period.

The study demonstrated that patients who developed stroke had a small but statistically significant decrease in left atrial reservoir, conduit, and booster pump strain compared to those who did not develop a stroke.  Conversely, those with a stroke had an increase in P-wave to A’ duration on tissue Doppler imaging, interventricular septal thickness, and indexed left atrial dimension compared to those who did not have a stroke.

 

When the investigators adjusted for clinical and echocardiographic correlates of stroke, the CHA₂DS₂-VASc score, anticoagulant use, a 10% change in left atrial reservoir strain, and a 10ms change in P-wave to A’ duration on tissue Doppler imaging were found to be independently associated with the risk of stroke.

The findings of this study suggest that echocardiographic parameters such as left atrial reservoir strain and PA-TDI, in addition to the initial stroke risk assessment via CHA₂DS₂-VASc score, not only provide enhanced stroke risk stratification but may also be helpful in making decisions regarding the use of anticoagulants in newly diagnosed atrial fibrillation patients.

The authors noted that death is a competing risk when calculating stroke incidence; thus, the risks of stroke presented in this study “are more important to a young individual compared to an older individual where the attendant risk of dying form unrelated causes is much greater.”

When asked to comment on these findings, Dr. Peter Zimetbaum, who is a Professor of Medicine at Harvard Medical School and Associate Chief and Director of the Cardiovascular division at Beth Israel Deaconess Medical Center, remarked that “our ability to assess the risk for stroke in patients with AF currently relies completely on clinical risk factors (IE Chadsvasc score)  – unfortunately this tool only performs with modest accuracy. Echocardiographic markers of left atrial and left atrial appendage size and function have been looked at for years with some evidence of predictive value but have not made it into routine clinical use – particularly because the most useful markers are determined only by TEE.”

When asked about the implications of this study on his clinical practice, Dr. Zimetbaum commented, “It will not change my practice at present but I applaud the development of this and other echo based predictors of stroke risk in AF populations. Novel echocardiographic markers like those tested in this study are attractive and may add value to our currently used clinical predictors of stroke risk. It remains to be determined if these measurements can be performed routinely with a high degree of reproducibility and if there predictive value holds up in larger studies.”