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[Discrimination attempt between stenoses of the left trunk and tritroncular involvement using univariate and
F Crosnier1, A Moïse, H Douard
1Département des épreuves d'effort et de la réadaptation, hôpital cardiologique du Haut-Lévêque, Pessac.
Insights
Exercise tests help identify patients with severe ischemia likely due to left main (LM) coronary artery stenosis. While not definitive, these tests guide selection for prompt coronary arteriography and surgery.
Area of Science:
- Cardiology
- Exercise Physiology
- Diagnostic Imaging
Background:
- Severe coronary artery stenosis, particularly left main (LM) and three-vessel (3V) disease, poses significant risks.
- Accurate non-invasive assessment of these conditions is crucial for timely intervention.
- Exercise testing is a common diagnostic tool, but its utility in differentiating severe stenosis types requires clarification.
Purpose of the Study:
- To evaluate the effectiveness of exercise testing in differentiating between left main (LM) and three-vessel (3V) coronary artery stenosis.
- To identify exercise test parameters indicative of LM coronary artery stenosis.
Main Methods:
- One hundred fifty patients with >70% 3V stenosis and 69 patients with >50% LM stenosis underwent symptom-limited maximal exercise tests.
- Anti-ischemic therapies were discontinued prior to testing.
- Univariate, linear discriminant function, and multivariate Cox model analyses were employed to assess exercise variables and ST depression.
Main Results:
- Univariate analysis revealed significant differences in cardiac work until ST depression (W1, W2) and exercise capacity (W3) between LM and 3V groups.
- Multivariate analysis indicated that early ST depression (1 mm after 4 min exercise) was more characteristic of LM stenosis (62% of LM patients vs. 28% of 3V patients).
- Linear discriminant analysis showed poor classification accuracy (53% correct).
Conclusions:
- Exercise tests do not definitively diagnose left main coronary artery stenosis but can identify patients with severe ischemia.
- Patients exhibiting early ischemic changes during exercise are highly likely to have LM stenosis and warrant further investigation.
- Prompt coronary arteriography and surgical intervention are recommended for patients suspected of having LM coronary artery stenosis.
Abstract:
One hundred and fifty patients with more than 70 p. 100 three vessel (3V) stenosis and 69 patients with more than 50 p. 100 left main (LM) coronary artery stenosis underwent an exercise test at maximum or symptom-limited level, after discontinuing all anti-ischaemic therapies. Three comparative statistical methods were used: 1. Univariate analysis. Among the mean values of the 17 variables studied, 6 differed significantly (p less than 0.05), viz.: cardiac work performed until the appearance, on the CM5 lead, of an ST depression (STd) of 1 mm (W1) (LM = 1,002 Kpm; 3V = 1,461 Kpm) and of 2 mm (W2) (LM = 2,445 Kpm; 3V = 2,904 Kpm); maximum STd/maximum heart rate ratio; rise of systolic pressure during exercise and rise of heart rate associated with a 2 mm STd less pronounced with LM; maximum exercise capacity (W3) (LM = 2,445 +/- 1,514; 3V = 2,904 +/- 2,095 Kpm). 2. Linear discriminant function analysis. No discriminant variable could be obtained (subjects well classified 53 p. 100, ill-classified 47 p. 100). 3. Multivariate analysis, Cox's model. This method demonstrated that stenosis of the LM coronary artery is characterized by the early appearance of ischaemia rather than by its severity. After 4 minutes of exercise, 62 p. 100 of LM patients and only 28 p. 100 of 3V patients had a 1 mm ST depression. It is concluded that exercise tests do not provide a certainty of LM stenosis, but they identify patients with severe ischemia who most probably have this type of stenosis. Such patients can then be selected for coronary arteriography and operated upon as soon as possible.