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Exercise testing in patients with electrocardiographic evidence of left ventricular hypertrophy
A A Alshami1, S R Jolly, F L Smith
1Department of Medicine, East Carolina University, Greenville, North Carolina.
Insights
Patients with electrocardiographic left ventricular hypertrophy (ECG-LVH) often show normal exercise thallium test results, despite frequent ECG changes. This suggests ECG-LVH may impact perfusion scan interpretation for coronary artery disease.
Area of Science:
- Cardiology
- Nuclear Medicine
- Diagnostic Imaging
Background:
- Left ventricular hypertrophy (LVH) can alter electrocardiogram (ECG) findings.
- Exercise thallium testing is used to diagnose coronary artery disease (CAD).
- The impact of ECG-defined LVH on exercise thallium test accuracy is not fully understood.
Purpose of the Study:
- To determine how left ventricular hypertrophy, identified by ECG, influences exercise thallium testing outcomes.
- To assess the prevalence of perfusion defects in patients with ECG-LVH undergoing stress testing.
Main Methods:
- Retrospective analysis of 107 patients with ECG-LVH undergoing exercise thallium testing.
- Comparison with a matched group of 255 patients without ECG-LVH.
- Quantification of lung thallium uptake (lung-to-heart ratio) to assess potential confounding factors.
Main Results:
- 73% of patients with ECG-LVH had normal perfusion scan results, despite 76% exhibiting additional ECG changes.
- Patients with ECG-LVH showed lower rates of transient and fixed myocardial perfusion defects compared to controls.
- Elevated myocardial thallium activity in ECG-LVH may explain reduced lung thallium uptake observed in controls with perfusion defects.
Conclusions:
- Exercise thallium testing frequently yields normal results in patients with ECG-LVH, even with concurrent ECG abnormalities.
- ECG-LVH may lead to a higher incidence of false-normal perfusion scans, potentially masking underlying CAD.
- Careful interpretation is needed when evaluating exercise thallium tests in patients with ECG-defined left ventricular hypertrophy.
Abstract:
The purpose of this study was to determine the influence of left ventricular hypertrophy, based on electrocardiographic evidence, on the results of exercise thallium testing. Patients with electrocardiographic evidence of left ventricular hypertrophy (ECG-LVH) and suspected of having coronary artery disease underwent exercise thallium testing. Retrospective analysis of 107 consecutive patients with ECG-LVH showed transient myocardial perfusion defects (TMPD) in 12 (11%), indicative of myocardial ischemia; 12 (11%) had fixed myocardial perfusion defects (FMPD), indicative of probable myocardial infarction; 5 had TMPD plus FMPD (5%), and scan results for 78 were normal (73%). In patients with ECG-LVH, additional ST changes were observed in 76% and chest pain in 7% of patients with ECG-LVH. In a matched comparison group of 255 patients not prescreened for ECG-LVH, TMPD was observed in 20%, FMPD in 16%, and TMPD plus FMPD in 26% of patients, and normal results were found in 38%. Electrocardiographic changes were found in 49% and chest pain in 20%. Hemodynamic responses to exercise were comparable between subgroups. Lung thallium uptake was quantified as the lung-to-heart thallium activity ratio (L-H) on the immediate exercise anterior planar images. In controls, a significant increase in L-H was observed in patients with TMPD and TMPD plus FMPD. This was not observed in patients with ECG-LVH, possibly because of elevated thallium myocardial activity as a result of increased left ventricular mass. The conclusion is that patients with ECG-LVH often had normal perfusion scan results (73%) on exercise despite a high incidence of additional ECG changes (76%).(ABSTRACT TRUNCATED AT 250 WORDS)