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Assessing left atrial size and pump function in ischemic stroke patients: Is cardiac MRI superior to transthoracic
Maxwell Isaac1, Senthil A Kumar1, Gregory F Petroski2
1The Division of Cardiology, Department of Medicine.
Insights
Cardiac MRI (cMRI) reveals larger left atrial abnormalities than transthoracic echocardiography (TTE) in ischemic stroke patients. Current guidelines may miss nearly 20% of potential cardiac embolism sources.
Area of Science:
- Cardiovascular Imaging
- Neurology
- Medical Diagnostics
Background:
- Transthoracic echocardiography (TTE) is the standard for assessing cardiac abnormalities post-ischemic stroke.
- The role of cardiac magnetic resonance imaging (cMRI) in enhancing this assessment remains unclear.
- Left atrial (LA) abnormalities are critical indicators of cerebral embolism risk.
Purpose of the Study:
- To compare the efficacy of cMRI versus TTE in evaluating LA size and function in ischemic stroke patients.
- To determine if cMRI offers superior detection of cardiac abnormalities compared to TTE.
Main Methods:
- 44 ischemic stroke patients underwent both TTE and cMRI.
- Biplane method used for LA diameter and area measurements.
- LA volume (LAV), LAV index (LAVI), LA Global Longitudinal Strain (GLS), and pump function were calculated and compared using statistical analysis (t-test, CCC, Bland-Altman).
Main Results:
- cMRI yielded significantly larger LAVI measurements (34.97 vs. 28.81, p=0.001) compared to TTE.
- Weak agreement observed between cMRI and TTE for LA size (CCC ρc = 0.397).
- Bland-Altman analysis showed cMRI-derived LAVI averaged 6.3 ml/m² greater than TTE.
Conclusions:
- TTE alone may underestimate critical LA abnormalities in ischemic stroke patients.
- Current TTE-based evaluations might miss potential cardiac embolism sources in approximately 20% of patients.
- cMRI may provide a more comprehensive assessment of cardiac abnormalities relevant to stroke etiology.
Objectives:
Current guidelines recommend transthoracic echocardiography (TTE) following an ischemic stroke as the primary technique to identify cardiac abnormalities associated with an increased risk of cerebral embolism. It is unclear whether cardiac magnetic resonance imaging (cMRI), a technique shown to provide increased imaging resolution, may also enhance the cardiac assessment of ischemic stroke patients. We compared cMRI with TTE in the evaluation of Left Atrial (LA) size and pump function in a cohort of 44 patients with ischemic stroke.
Materials And Methods:
The biplane method was utilized to acquire LA diameters as well as area measurements in both TTE and cMRI. We calculated LA volume (LAV), LAV index (LAVI), LA Global Longitudinal Strain (GLS) and LA pump function. Results were compared using paired two sample for means t-test. Lin's concordance correlation coefficient (CCC) and Bland-Altman methods quantified the agreement of measurements obtained by TTE and cMRI.
Results:
LAVI measurements by cMRI were significantly larger (34.97 v. 28.81; p = 0.001) than by TTE. The concordance correlation demonstrated only a weak agreement between LA size measured by cMRI and TTE (ρc = 0.397; p= 0.001, 95% CI 0.16 - 0.59), and the Bland-Altman plot demonstrated that LAVI measured by cMRI averaged 6.3 ml/m2 larger magnitude than those obtained by TTE.
Conclusions:
Using TTE alone leads to an underestimation of LA abnormalities important in the evaluation of ischemic stroke patients. Nearly one in every five ischemic stroke patients evaluated based on the current guidelines may have a missed potential source of cardiac embolism.
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