Association of left atrial fibrosis detected by delayed-enhancement magnetic resonance imaging and the risk of stroke in patients with atrial fibrillation

Marcos Daccarett, Troy J Badger, Nazem Akoum, Nathan S Burgon, Christian Mahnkopf, Gaston Vergara, Eugene Kholmovski, Christopher J McGann, Dennis Parker, Johannes Brachmann, Rob S Macleod, Nassir F Marrouche, Marcos Daccarett, Troy J Badger, Nazem Akoum, Nathan S Burgon, Christian Mahnkopf, Gaston Vergara, Eugene Kholmovski, Christopher J McGann, Dennis Parker, Johannes Brachmann, Rob S Macleod, Nassir F Marrouche

Abstract

Objectives: This study tried to determine the association between left atrial (LA) fibrosis, detected using delayed-enhanced magnetic resonance imaging (DE-MRI), and the CHADS(2) score (point system based on individual clinical risk factors including congestive heart failure, hypertension, age, diabetes, and prior stroke) variables, specifically stroke.

Background: In patients with atrial fibrillation (AF), conventional markers for the risk of stroke base their higher predictive effect on clinical features, particularly previous stroke history, and not individual LA pathophysiological properties. We aimed to determine the association between LA fibrosis, detected using DE-MRI, and the CHADS(2) score variables, specifically stroke.

Methods: Patients with AF who presented to the AF clinic and received a DE-MRI of the LA were evaluated. Their risk factor profiles, including a CHADS(2) score, were catalogued. The degree of LA fibrosis was determined as a percentage of the LA area. Any history of previous strokes, warfarin use, or cerebrovascular disease was recorded.

Results: A total of 387 patients, having a mean age of 65 ± 12 years, 36.8% female, were included in this study. A history of previous stroke was present in 36 (9.3%) patients. Those patients with previous strokes had a significantly higher percentage of LA fibrosis (24.4 ± 12.4% vs. 16.2 ± 9.9%, p < 0.01). A larger amount of LA fibrosis was also seen in those patients with a higher CHADS(2) score (≥ 2: 18.7 ± 11.4 vs. <2: 14.7 ± 9.2, p < 0.01). A logistic regression analysis of all variables except strokes (CHAD score) demonstrated that LA fibrosis independently predicted cerebrovascular events (p = 0.002) and significantly increased the predictive performance of the score (area under the curve = 0.77).

Conclusions: Our preliminary, multicenter results suggest DE-MRI-based detection of LA fibrosis is independently associated with prior history of strokes. We propose that the amount of DE-MRI-determined LA fibrosis could represent a marker for stroke and a possible therapeutic target with potential applicability for clinical treatment for patients with AF.

Copyright © 2011 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1. Staging of DE-MRI LA Structural…
Figure 1. Staging of DE-MRI LA Structural Remodeling Quartile Distribution
Delayed-enhancement magnetic resonance images representing posteroanterior views of the left atrium in patients with Stage (quartile) I (A: 2.7% enhancement), Stage II (B: 10.2% enhancement), Stage III (C: 19.4%), and Stage IV (D: 38.4% enhancement). Left atrial enhancement is represented as green areas. Color Look-Up Table mask has been applied to the rendered images to better differentiate enhanced and nonenhanced tissue. DE-MRI = Delayed-enhancement magnetic resonance imaging; LA = left atrial; PA = posteranterior.
Figure 2. Relationship of LA Structural Remodeling…
Figure 2. Relationship of LA Structural Remodeling and Stroke
Delayed-enhancement magnetic resonance imaging left atrial structural remodeling according to the history of strokes (A) and risk profile (B). Patients who experienced a prior stroke had a significantly higher percentage of LA fibrosis compared to those without history of a previous stroke (24.4 ± 12.4% vs. 16.1 ± 9.8%, p ≤ 0.001). CHADS2 = point system based on individual clinical risk factors including congestive heart failure, hypertension, age, diabetes, and prior stroke; other abbreviation as in Figure 1.
Figure 3. Incidence of Stroke Among the…
Figure 3. Incidence of Stroke Among the Various Levels of LA Structural Remodeling
History of stroke (A) and risk score prevalence for stroke (B) according the different delayed-enhancement magnetic resonance imaging left atrial structural remodeling stages (quartiles). Atrial fibrillation patients with higher risk factor profiles for stroke (CHADS2 ≥2) had a significantly larger amount of left atrial fibrosis when compared to those patients who had either a moderate- or low-risk profile (see also Table 2). Abbreviations as in Figures 1 and 2.

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