Assessment of left atrial structural remodeling in patients with cryptogenic stroke - lessons learned from LGE-MRI

Background

Cryptogenic embolic strokes of undetermined source (ESUS) are thought to comprise about 25% of all ischemic strokes. Late-Gadolinium MRI (LGE-MRI) allows detection and quantification of left atrial structural remodeling (LA-SRM). We sought to compare the degree of LA-SRM using LGE-MRI in patients with ESUS and in patients with embolic stroke of know origin, especially in those with atrial fibrillation (AFIB).

Methods

A total of fifty patients (31male (62%), Age 61.1 ± 14.2 years) with TIA or Stroke underwent LGE-MRI of the left atrium within 4 days after the event to assess for LA-SRM. Each LGE-MRI was segmented by isolating the LA wall and quantified for the relative extent of fibrotic remodeling using the Corview-Software (Merisight ™, Figure 1). Brain-CT or MRI, TEE, Sonography of the cerebral blood vessels and 24 hour ECG were performed in all patients.

Figure 1

3D-Model of the left atrium. Example of a patient with extensive LA-SRM. Blue reflects healthy LA-tissue, while fibrotic areas are given in green. Pulmonary veins in great. PA-view (Merisight TM).

Results

A total of 24 patients (48%) were specified with the diagnosis of ESUS, while a reason for the stroke event (AFIB, significant carotids stenosis, LAA-thrombus, persistent foramen ovale) was found in 26 patients (52%). The degree of left atrial remodeling was comparable in both groups (12.17 ± 5.23 vs. 12.15% ± 5.46%; p = 0.993; Figure 2). Overall, 15 patients (30%, 11 males) had a history of or were currently found with atrial fibrillation as a major reason for embolic stroke. Degree of LA-SRM (12.26% ± 6.4%) was comparable to those stroke patients with sinus rhythm (12.11 ± 4.85, p=n.s., Figure 3).

Figure 2

Degree of LA-SRM in patients with embolic strokes of undetermined source (red column) and in patients with stroke of known origin (blue column).

Figure 3

Degree of LA-SRM in patients with embolic stroke and atrial fibrillation (red column) and in embolic stroke patients with normal sinus rhythm (blue column).

Conclusions

From our preliminary results the degree of left atrial structural remodeling detected using LGE-MRI is comparable in patients with know origin of stroke and in those with so-called cryptogenic stroke. Thus, the extent of LA-SRM appears to play a critical role in the pathophysiology of embolic stroke and should be considered in the diagnosis, treatment, and risk stratification in stroke patients.