Enlarged Left Atrium Points to AF in Cryptogenic Stroke

ISTANBUL, Turkey — For patients with cryptogenic stroke, larger left atrial volume is a strong predictor that atrial fibrillation (AF) is the underlying cause, a new study suggests.

This sign can be an important clue, especially in cases of paroxysmal AF, researchers say. Given differences in treatment of patients with ischemic stroke caused by AF, diagnosis of the condition is important.

Timothy Bates, MD, head of the Swan District Hospital Comprehensive Stroke Unit in Middle Swan (Perth), Western Australia, and colleagues therefore investigated the echocardiographic predictors of AF through a retrospective study of patients admitted to their stroke unit with confirmed ischemic stroke.

"The LAVI [left atrial volume index] was the most powerful predictor of cardioembolic stroke, an association remaining significant after adjusting for age, mitral valve disease, and diastolic dysfunction," the researchers concluded.

They presented their findings here at the 9th World Stroke Congress (WSC).

For this analysis, investigators classified patients according to three groups (n = 87): large-artery stroke with greater than 50% stenosis but no AF (n = 30); small-vessel disease only and no AF (n = 27); or cardioembolic stroke (n = 30), defined as proven AF on electrocardiography or Holter monitoring but no stenosis in a perfusing artery. The same provider performed echocardiography on all patients, and a blinded observer determined the cause of the stroke.

All three patient groups were similar in baseline demographic and clinical characteristics except that the patients with cardioembolic stroke were older than the other two groups (76.3 vs 66.0 to 67.7 years; P = .03), and more were taking a β-blocker (53% vs 22% to 27%; P = .026). Lipid values, including apolipoprotein components, did not discriminate among the groups.

In addition to being older and taking more β-blockers, the cardioembolic stroke group had a higher LAVI, more diastolic dysfunction, and more mild or moderate mitral valve regurgitation. LAVI is a measure of left atrial volume normalized for body size. There were no significant differences between the large-artery and small-vessel disease groups.

A LAVI greater than 34 mL/m² was associated with a greater than 7-fold increased risk for cardioembolic stroke (hazard ratio, 7.1; P < .001).

Table. Baseline Echocardiographic Values

Didier Leys, MD, PhD, professor of neurology at the University of Lille, France, commented that the findings were not completely new because AF is an important known cause of stroke, and patients with AF generally have an enlarged left atrium. Nonetheless, he said they were still interesting.

"Many patients with atrial fibrillation have paroxysmal atrial fibrillation so they have no atrial fibrillation when they arrive," he told Medscape Medical News. "I think the message is here that if we have a patient with a stroke of unknown cause...and a very large left atrium, we should of course think that it's likely to be a case of paroxysmal atrial fibrillation."

He said a diagnostic work-up for a cause of stroke may be completely negative, but certain clues may point to a cardioembolic origin, such as several ischemic strokes in different vascular territories, at different dates, usually with normal results and no detectable stenosis or atheroma.

"In this case, we say it's likely to be cardioembolic because of the brain profile," he said, "but to be sure we need to prove that there is atrial fibrillation or thrombosis or something else."

Dr Bates and Dr Leys have disclosed no relevant financial relationships.

9th World Stroke Congress (WSC). Abstract 340. Presented October 23, 2014.

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Cite this: Enlarged Left Atrium Points to AF in Cryptogenic Stroke - Medscape - Nov 18, 2014.