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Silent myocardial ischaemia: the Tan Tock Seng experience
Insights
Patients with silent myocardial ischemia on treadmill exercise stress tests (TMX) showed a higher maximal double product and better outcomes than symptomatic patients. This suggests silent ischemia may indicate a higher workload tolerance and less adverse cardiac events.
Area of Science:
- Cardiology
- Exercise Physiology
Background:
- Treadmill exercise stress test (TMX) results for ischemia are based on ST-segment depression.
- Patients with positive TMX results can be symptomatic or asymptomatic.
Purpose of the Study:
- To investigate differences in outcomes between symptomatic and asymptomatic patients with coronary artery disease and positive TMX results.
Main Methods:
- A cohort of 39 patients with coronary artery disease and positive TMX results were divided into symptomatic (n=16) and asymptomatic (n=23) groups.
- Patients were followed for a mean of 16.9 and 15.2 months, respectively.
- Key clinical, demographic, and exercise parameters were compared, including maximal double product and cardiac events.
Main Results:
- No significant differences were found in age, sex, risk factors, medications, or cholesterol levels between groups.
- The maximal double product during TMX was significantly higher in the silent ischemia group (p=0.004).
- The silent ischemia group experienced fewer cardiac events and revascularizations (2 total) compared to the symptomatic group (9 total), with a statistically significant difference in overall outcome (p=0.002).
Conclusions:
- Patients with silent myocardial ischemia exhibit a higher maximal double product on TMX, indicating a greater maximal workload.
- Silent myocardial ischemia is associated with a less adverse clinical outcome compared to symptomatic ischemia in patients with coronary artery disease.
Abstract:
The results of treadmill exercise stress test (TMX) for ischaemia is based on ST-segment depression. Patients with positive test may or may not be symptomatic. This study examines if there are any differences between these two groups of patients. A total of thirty-nine patients with coronary artery disease and positive TMX results in 1988 was studied. There were 16 patients with chest pain and 23 without. They were followed-up for a mean period of 16.9 and 15.2 months respectively. The following factors were found not to be statistically significant between these two groups of patients: age, sex, race, height, weight, history of hypertension, diabetes mellitus or smoking, indication for the test, use of drugs, total and HDL-cholesterol, exercise duration and the initial double product. The difference between the maximal double product of the two groups was statistically significant (p = 0.004). In the follow-up period, in the group of patients with silent myocardial ischaemia, one had a cardiac event and one underwent revascularisation. While in the symptomatic group, two had cardiac events and seven underwent revascularisation. There were no deaths in either group. The difference in overall outcome was significant statistically (p = 0.002). Therefore, patients with silent myocardial ischaemia have a higher maximal double product in TMX; hence a higher maximal workload and a less adverse outcome compared to symptomatic patients.