Clinical Investigation
Electrophysiology
Predicting left atrial thrombi in atrial fibrillation

https://doi.org/10.1016/j.ahj.2009.12.043Get rights and content

Background

The aim of the study was to determine whether CHADS2 score is predictive of left atrial appendage thrombus (LAAT) in nonvalvular atrial fibrillation (AF). Strategies for effective stroke prevention in AF require tools capable of identifying those patients at greatest risk for embolization of LAAT and most likely to benefit from warfarin. Nearly half of strokes in AF are due to noncardioembolic mechanisms for which antiplatelet therapy would be more appropriate. Previous attempts to develop such tools have been limited by including patients without proven cardioembolism.

Methods

Nonanticoagulated, nonvalvular AF patients with (cases) or without (controls) LAAT by transesophageal echocardiography were identified using Mayo Clinic Echocardiography and Cardioversion Unit Databases (Rochester, MN). Type and duration of AF, CHADS2 score, and echocardiography measures were compared to determine variables predictive of LAAT.

Results

The CHADS2 score was significantly higher for cases (n = 110, mean ± SD 2.8 ± 1.6) compared to controls (n = 387, 1.6 ± 1.3). By multivariate analysis, independent predictors of LAAT included heart failure (HR 5.78, P < 0001), prior stroke/transient ischemic attack (HR 3.94, P < .0001), diabetes mellitus (HR 1.98, P = .015), permanent AF (HR 3.02, P < .05), AF duration (HR 2.24, P < .05), and spontaneous echocardiographic contrast (HR 4.35, P = .005). Using these elements, a new scoring system provided cleaner case-control separation (C-index 0.90) and higher predictive power compared to CHADS2 (C-index 0.71).

Conclusions

The CHADS2 score predicts the presence of LAAT in AF patients. Some, but not all, variables within this score are predictive of LAAT. By including only echo and clinical variables predictive of LAAT, our novel scoring system better identified those AF patients at greatest cardioembolic risk.

Section snippets

Study population

In a case control study design, Mayo Clinic Echocardiography Laboratory and Cardioversion Unit Databases (Rochester, MN) were used to identify all patients with nonvalvular AF who had LAAT detected by TEE (cases). Cases with heart valve prosthesis (biologic or mechanical) or more than moderate heart valve disease were excluded. Cases who had received warfarin, heparinoid, or direct thrombin inhibitor therapy within 30 days before TEE were also excluded.

The control group consisted of concurrent

Patient population

Between 1995 and 2005, there were 110 nonvalvular AF patients (mean age 72 ± 11 years, range 26-96 years, 39% women) who had LAAT detected by TEE (cases). Two patients of this group had thrombus within the left atrium cavity; all others had LAAT. Twenty cases had previously received warfarin; however, this medication had been stopped at least 30 days before LAAT detection. All patients had international normalized ratio ≤1.1 at the time of LAAT diagnosis.

For cases, the TEE indication was source

Discussion

There are 3 lines of evidence that embolic stroke in patients with AF originates in the LAA. First comes from pathology literature. Aberg26 was studying necropsy data from patients with valvular and nonvalvular AF dying from embolic stroke and found that thrombi within LAA were relatively common in patients with nonvalvular AF. Second, there are clinical data for AF patients undergoing TEE for source of embolism. In AF patients with acute thromboembolism, there was a high prevalence (43%) of

Disclosures

None of the authors have potential conflicts of interest to disclose.

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    This study was supported by Mayo Clinic Foundation CR 20 grant.

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