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Left ventricular dysfunction during exercise in patients with angina pectoris and angiographically normal coronary
J Taki1, K Nakajima, A Muramori
1Department of Nuclear Medicine, Kanazawa University School of Medicine, Japan.
Insights
Patients with syndrome X, characterized by chest pain and normal coronary arteries, frequently exhibit left ventricular dysfunction during exercise. This dysfunction manifests as an impaired ejection fraction response, even without blocked arteries.
Area of Science:
- Cardiology
- Nuclear Medicine
- Physiology
Background:
- Syndrome X, also known as cardiac syndrome X, presents with angina pectoris and ST segment depression during exercise but has normal coronary angiograms.
- The underlying mechanisms of syndrome X and its impact on left ventricular function remain incompletely understood.
Purpose of the Study:
- To investigate left ventricular (LV) function during exercise and recovery in patients with syndrome X.
- To compare LV function between patients with syndrome X and a control group with atypical chest pain and normal coronary arteries.
Main Methods:
- Utilized a continuous left ventricular function monitor with a cadmium telluride detector (CdTe-VEST) for real-time monitoring.
- Administered technetium-99m labeled red blood cells and performed supine ergometric exercise in 14 patients with syndrome X and 14 controls.
- Monitored left ventricular ejection fraction (EF) every 20 seconds during exercise and recovery.
Main Results:
- Left ventricular ejection fraction (EF) response was impaired (≤5% increase from rest to peak exercise) in 11 out of 14 patients with syndrome X.
- Resting EF was similar between groups, but the increase from rest to peak exercise was significantly lower in syndrome X patients (-3.1% vs. 14.7%, P < 0.001).
- Patients with syndrome X showed a lower and delayed 'EF overshoot' phenomenon after exercise cessation compared to controls (P < 0.001 and P < 0.05, respectively).
Conclusions:
- Left ventricular dysfunction is frequently observed during exercise in patients with syndrome X, despite angiographically normal epicardial coronary arteries.
- The impaired EF response and altered recovery dynamics suggest an underlying issue with myocardial function or perfusion in syndrome X.
- CdTe-VEST monitoring provides valuable insights into exercise-induced cardiac dysfunction in patients with unexplained chest pain.
Abstract:
Left ventricular function during exercise and recovery was investigated in patients with angina pectoris, ST segment depression during exercise and angiographically normal coronary arteries (syndrome X) using a continuous left ventricular function monitor with cadmium telluride detector (CdTe-VEST). Fourteen patients with syndrome X and 14 patients with atypical chest pain without ST segment depression during exercise and normal coronary arteries (control group) performed supine ergometric exercise after administration of 740-925 MBq of technetium-99m labelled red blood cells, and left ventricular function was monitored every 20 s using CdTe-VEST. Left ventricular ejection fraction (EF) response was impaired (< or = 5% increase from rest to peak exercise) in 11 or 14 patients with syndrome X but in none of the control patients. Resting EF was similar in the two groups (62.1% +/- 6.7% in patients with syndrome X, 61.9% +/- 6.2% in controls); however, EF increase from rest to peak exercise was lower in syndrome X (-3.1 +/- 9.5% vs 14.7% +/- 7.4%, P < 0.001). After cessation of exercise, all patients showed rapid EF increase over baseline and this EF overshoot was lower (19.3% +/- 8.3% vs 26.4% +/- 7.3%, P < 0.001) with the time to EF overshoot longer (114 +/- 43 s vs 74 +/- 43 s, P < 0.05) in patients with syndrome X. Thus, in patients with syndrome X, left ventricular dysfunction was frequently observed during exercise in spite of normal epicardial coronary arteries.