What question did this study set out to answer?

To identify clinical and echocardiographic characteristics that determine whether thromboemboli lodge in peripheral arteries versus the cerebral circulation in non-valvular atrial fibrillation.

January 1, 2008Thrombosis and Haemostasis

Clinical and echocardiographic measures governing thromboembolism destination in atrial fibrillation

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Why the study?

Do specific clinical and echocardiographic characteristics predict thromboembolism destination in patients with non-valvular atrial fibrillation?

Key Points

To identify clinical and echocardiographic characteristics that determine whether thromboemboli lodge in peripheral arteries versus the cerebral circulation in non-valvular atrial fibrillation.
Inception cohort study comparing individuals with incident peripheral embolism (n=72) to a randomly selected group with atrial fibrillation-related stroke (n=100) between 1995 and 2005.
Evaluated clinical comorbidities, CHADS-2 scores, and echocardiographic measures, using multivariate analysis to identify independent predictors of peripheral embolism.
Extremity arteries accounted for 85% of peripheral embolic events, with lower extremity involvement occurring twice as frequently as upper extremity involvement.
Severe left ventricular dysfunction, spontaneous echo contrast, and left atrial thrombus were 2- to 3-fold more frequent in peripheral embolism patients compared to stroke patients.
Multivariate analysis identified age >75 years as an independent predictor of peripheral embolism (HR 2.3, 95% CI 1.3–3.9; p=0.05), with severe left atrial enlargement (HR 1.8, 95% CI 0.99–3.1; p=0.055) showing borderline significance.

Structured PICO

Do specific clinical and echocardiographic characteristics predict thromboembolism destination in patients with non-valvular atrial fibrillation?

Population

172 patients with non-valvular atrial fibrillation, comprising an inception cohort with incident peripheral embolism (n=72, 1995-2005) and a randomly selected comparison group with atrial fibrillation-related stroke (n=100).

Outcome

Thromboembolism destination (peripheral embolism vs. stroke)hard clinical

Advanced age and potentially left atrial enlargement increase the propensity for larger thrombi in atrial fibrillation, which are more likely to bypass the cerebral circulation and cause peripheral embolism.

Implication

Age >75 may flag higher peripheral embolism risk in AF; leaves open validation of destination-specific predictors.

Abstract

Although infrequent, embolic occlusion to non-cerebral arteries may result in limb loss, organ failure, and death. The aim of this study was to define clinical and echocardiographic characteristics determining thromboembolism destination in non-valvular atrial fibrillation. An inception cohort of individuals (n=72) were identified with incident peripheral embolism in the setting of non-valvular atrial fibrillation (1995-2005). A randomly selected group of atrial fibrillation related stroke patients (n=100) were identified for comparison. Arteries of the extremities were the most common site of embolism (85%); lower extremity involvement was twice as common compared with the upper extremity. Clinical features distinguishing peripheral embolism from stroke included age>75, heart failure and hypertension. Severe left ventricular dysfunction, spontaneous echo contrast and left atrial thrombus were 2-3 fold more common in peripheral embolism patients. Mean CHADS-2 scores were low and comparable for both groups. By multivariate analysis, age>5 years (hazard ratio [HR] 2.3, 95% confidence interval [CI] 1.3-3.9; p=0.05) was predictive of peripheral embolism. After adjustment for age>75 years, severe left atrial enlargement (HR 1.8, 95% CI 0.99-3.1; p=0.055) and CHADS score (HR 1.2, 95% CI 0.99-1.6; p=0.06) were of borderline significance. In conclusion, several clinical and echocardiographic measures distinguish the clinical presentation of thromboembolism in non-valvular atrial fibrillation. Small emboli are destined to lodge in the cerebral circulation as a result of hydrodynamic, anatomic, and physical factors. Advanced age, atrial enlargement and other co-morbidities may increase the propensity for the formation of larger thrombi which may bypass the carotid orifice merely as a function of size.