Author + information
- Tyler J. Peterson, MD†,
- Farhan J. Khawaja, MD‡,
- Garvan C. Kane, MD, PhD†,
- Patricia A. Pellikka, MD† and
- Robert B. McCully, MD†,⁎ ()
- ↵⁎Division of Cardiovascular Medicine, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905
To the Editor:
Left atrial size has been shown to be an important marker of cardiovascular risk burden, providing prognostic information in different patient populations (1–3). Previously, a small study published by Alsaileek et al. (4) suggested that a normal left atrial volume index (LAVI) was highly predictive of a normal stress echocardiogram. In that study, performed in 180 patients, no patient with an LAVI ≤28 ml/m2 had stress-induced myocardial ischemia and only 5.7% had abnormal stress echocardiograms. Our objective was to evaluate the predictive value of LAVI for stress echocardiographic abnormalities in a larger patient cohort undergoing stress echocardiography, studied methodically over a 12-month period.
In 2006, all patients referred to the stress echocardiography laboratory at Mayo Clinic (Rochester, Minnesota) also underwent 2-dimensional and Doppler echocardiographic assessment of left ventricular diastolic function at baseline and at peak stress. Left atrial size was routinely measured at baseline. The biplane area-length method was used to calculate the left atrial volume, which was indexed to body surface area. Stress echocardiography was then performed. Patients who did not give permission for their data to be used for research purposes were excluded from the study, as were patients who had at least moderate aortic or mitral stenosis or at least moderately severe aortic or mitral regurgitation, chronic atrial fibrillation, or dilated cardiomyopathy. Patients with normal stress echocardiograms had normal left ventricular regional and global systolic function at baseline and no stress-induced wall motion abnormalities. Patients with abnormal stress echocardiograms had baseline regional wall motion abnormalities (fixed) or stress-induced regional wall motion abnormalities (ischemic) or both (mixed). Stress echocardiograms were positive for ischemia if new or worsening regional wall motion abnormalities developed with stress (ischemic or mixed). Potential associations between LAVI measurements and abnormal and positive stress echocardiographic results were examined using the chi-square test. Significance was inferred at p < 0.05.
A total of 7,336 patients were included in the study. Exercise echocardiograms were performed in 56% of patients and dobutamine stress echocardiograms performed in 44%. The mean age was 63.3 ± 13.3 years; 54% were men, 19% had diabetes, and 22% had known coronary artery disease, defined as a history of myocardial infarction or prior coronary revascularization. The stress echocardiograms were performed for evaluation of chest pain or dyspnea in 55% of patients, preoperative assessment in 27%, evaluation of known coronary artery disease in 10%, and other reasons in 8%.
There was a significant association between the size of the left atrium and abnormal stress echocardiographic results (Fig. 1). The larger the left atrium, the greater the likelihood that the stress echocardiogram would be abnormal (p < 0.0001) or that there would be echocardiographic evidence of stress-induced ischemia (p < 0.0001).
However, among patients with normal-sized atria (≤28 ml/m2), 23% had abnormal stress echocardiograms (ischemic, mixed, or fixed) and 17% were positive for stress-induced myocardial ischemia (ischemic or mixed). Even among patients with the smallest left atrial volumes (LAVI ≤20 ml/m2), 14% were positive for stress-induced myocardial ischemia.
In this large population referred for clinically indicated stress echocardiography, there was an association between the size of the left atrium and stress echocardiographic findings in that the larger the left atrium, the greater the likelihood that stress echocardiograms would be abnormal. However, patients who had normal left atrial size also had abnormal or positive stress echocardiographic results (23% and 17%, respectively) in this study. Thus, the findings of a normal-sized left atrium on echocardiography should not be used as a surrogate for predicting the absence of stress-induced myocardial ischemia.
- American College of Cardiology Foundation
- Moller J.E.,
- Hillis G.S.,
- Oh J.K.,
- et al.
- Alsaileek A.A.,
- Osranek M.,
- Fatema K.,
- McCully R.B.,
- Tsang T.S.,
- Seward J.B.