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Multifactor evaluation of the determinants of ischemic electrocardiographic response to maximal treadmill testing in
Insights
Maximal exercise tests (MEXT) show higher sensitivity for detecting coronary artery disease with more severe and widespread arterial narrowing. The number of stenosed vessels and overall stenosis severity are key indicators, not collateral vessels or ventricular function.
Area of Science:
- Cardiology
- Diagnostic Imaging
- Exercise Physiology
Background:
- Coronary artery disease diagnosis relies heavily on treadmill stress tests, but detailed correlations between coronary pathoanatomy and electrocardiogram (ECG) ischemic responses are limited.
- Understanding these correlations is crucial for accurate diagnosis and risk stratification.
Purpose of the Study:
- To investigate the relationship between specific features of coronary artery stenosis and the ischemic response detected by maximal exercise tests (MEXT).
- To identify which pathoanatomical factors most significantly influence the sensitivity of MEXT in detecting coronary artery disease.
Main Methods:
- Evaluated 91 patients with significant coronary stenosis (≥75% narrowing) using graded maximal exercise tests (MEXT) and coronary arteriography.
- Defined a positive MEXT as ≥0.1 mV horizontal or downsloping S-T segment depression lasting ≥0.08 seconds.
- Correlated MEXT results with the number, severity, and location of coronary artery stenoses.
Main Results:
- Overall MEXT sensitivity was 65% (59/91 patients), increasing with the number of diseased vessels (42% single, 66% double, 80% triple).
- Stenosis in the left anterior descending artery, particularly proximal lesions, and higher total stenosis severity/number correlated with positive MEXT.
- Lower poststenotic myocardial perfusion index was associated with positive MEXT.
Conclusions:
- MEXT sensitivity in coronary artery disease is primarily determined by the extent and severity of coronary artery narrowing, including the number of vessels involved and overall stenosis index.
- Specific stenosis location, like proximal to the left anterior descending artery, can influence MEXT results.
- Factors like collateral vessels, ventricular function, and prior infarction were not significant predictors of MEXT positivity.
Abstract:
Despite widespread use of treadmill stress in the detection of coronary disease, detailed information relating the important features of coronary pathoanatomy to the ischemic response noted on the electrocardiogram is lacking. Accordingly, 91 consecutive patients undergoing graded maximal exercise tests (MEXT) who were found to have clinical stenosis (larger than or equal to 75 per cent luminal narrowing) of at least one of the three major coronary arteries on coronary arteriography were evaluated. Positive MEXT was defined as larger than or equal to 0.1 mV horizontal or downsloping S-T segment depression larger than or equal to 0.08 second beyond J point. Over-all sensitivity of positive MEXT was 59 of 91 (65 per cent) patients; 11 of 26 (42 per cent) with single vessel stenosis, 20 of 30 (66 per cent) with two vessel disease and 28 of 35 (80 per cent) with three vessel disease. In patients with two vessel disease, the frequency (p less than 0.05) of positive MEXT was greater in those with (15 of 21;71 per cent) than in those without (five of nine; 55 per cent) stenosis of the left anterior descending artery. Concerning the site of intravessel stenosis, the frequency of positive MEXT was greater (p less than 0.05) with stenosis proximal to the left anterior descending artery in patients with one vessel disease. Quantification of total numbers of intra- and intervessel stenoses revealed 2.7 stenoses in the 59 patients with positive MEXT in contrast (p less than 0.01) to 1.9 in 32 patients with negative MEXT. Similarly, graded luminal narrowing index of severity of total stenoses per patient was 9.9 in those with positive MEXT compared (p less than 0.01) to 6.1 in those with negative MEXT. The poststenotic myocardial perfusion index, estimated by graded distal vessel opacification per major vessel disease, was only 1.5 in those with positive MEXT contrasted (p less than 0.01) to 2.4 in those with negative MEXT. These data indicate that sensitivity of positive MEXT in patients with coronary disease is most closely determined by the number of major coronary vessels involved, the total number of major vessels stenosed, the severity of total stenoses and poststenotic distal vessel perfusion. Less important factors are the precise site of intravessesl stenosis and the specific major coronary artery involved, although stenosis proximal to the left anterior descending artery favored positive MEXT. Unimportant variables were the quality of collateral vessels, ventricular function and prior inferior infarction. Angina occurred more frequently in those with positive MEXT, and marked degree of positive MEXT indicated stenosis proximal to the left anterior descending artery.