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Left ventricular dysfunction during dobutamine stress echocardiography in patients with syndrome X and positive
G Fragasso1, S L Chierchia, C Lu
1Divisione di Cardiologia, Istituto Scientifico Ospedale San Raffaele, Milano e Roma.
Insights
Syndrome X patients with perfusion defects may experience left ventricular dysfunction. Reversible ischemia explains chest pain in about a third of these patients, linking coronary flow reserve and dysfunction.
Area of Science:
- Cardiology
- Nuclear Cardiology
- Echocardiography
Background:
- Syndrome X (angina with normal coronary arteries) often presents with myocardial perfusion defects.
- The relationship between perfusion defects, coronary flow reserve, and left ventricular dysfunction in Syndrome X is not fully understood.
Purpose of the Study:
- To investigate if perfusion defects in Syndrome X patients are linked to reduced coronary flow reserve and subsequent regional left ventricular dysfunction.
Main Methods:
- Twenty-two Syndrome X patients underwent dobutamine stress echocardiography (DSE) and 99m-Tc-MIBI scintigraphy.
- Wall motion score index (WMSI) was assessed at rest and peak stress.
- Perfusion defects and DSE findings were correlated with symptoms and ECG changes.
Main Results:
- Over half of Syndrome X patients (53%) showed inducible left ventricular dysfunction on DSE.
- Myocardial perfusion defects were present in all patients.
- In 32% of patients, dobutamine-induced dysfunction occurred in areas of exercise-induced hypoperfusion.
Conclusions:
- Syndrome X patients with perfusion defects frequently develop regional left ventricular dysfunction during stress.
- While perfusion defects and dysfunction can coexist, their locations may differ.
- Reversible ischemia, characterized by limited flow reserve and inducible dysfunction, is identified as the cause of chest pain in approximately one-third of patients.
Aims:
A sizeable proportion of patients with angina, angiographically smooth coronary arteries and positive exercise test (syndrome X) have stress/rest myocardial perfusion defects. The aim of the study was to assess whether perfusion defects are dependent upon a reduction in coronary flow reserve causing regional left ventricular dysfunction in syndrome X patients.
Methods And Results:
Twenty-two syndrome X patients underwent dobutamine stress echocardiography (DSE). All had stress-induced perfusion defects documented by 99m-Tc-MIBI scintigraphy. Resting and peak DSE wall motion score index (WMSI) were evaluated. Six patients exhibited resting wall motion abnormalities in 10 segments (WMSI 1.05 +/- 0.11). DSE was positive in 12 patients (53%), in whom 16 myocardial segments were involved: of these, 12 were normokinetic and 4 hypokinetic at rest. Peak WMSI was 1.17 +/- 0.17 (p < 0.05 vs rest). Of the 12 patients with a positive DSE, 9 also showed diagnostic ECG changes and 6 complained of angina. Of the 10 patients with negative DSE, 5 had angina and 5 (one with angina) showed ECG changes. In 7 patients (7 segments) (32%), the location of dobutamine-induced wall motion abnormalities coincided with the area where exercise-induced hypoperfusion was observed with MIBI.
Conclusions:
More than a half of syndrome X patients with myocardial perfusion abnormalities also develop regional LV dysfunction during DSE. However, the site of perfusion defects and wall motion abnormalities can be different. Reversible ischemia, defined as a parallel limitation of flow reserve and inducible dysfunction, could be identified as the cause of chest pain in almost one-third of patients.
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