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Effect of increased free fatty acids on myocardial oxygen extraction and angina threshold during atrial pacing
Insights
Elevated free fatty acids (FFA) do not increase myocardial oxygen demand or ischemia in patients with coronary artery disease. This study found no significant impact on oxygen extraction or ischemic symptoms during pacing tests.
Area of Science:
- Cardiology
- Metabolic Research
Background:
- Coronary artery disease (CAD) involves impaired myocardial oxygen supply.
- The role of elevated arterial free fatty acids (FFA) in myocardial ischemia is not fully understood.
Purpose of the Study:
- To investigate if increased arterial FFA levels exacerbate myocardial oxygen demand and ischemia in patients with CAD.
Main Methods:
- 15 patients with CAD underwent atrial pacing tests (PT) before and during heparin infusion to elevate FFA.
- Monitored for ischemic symptoms, ECG changes (ST-segment depression).
- Measured myocardial extraction of lactate, inorganic phosphate, oxygen, and FFA.
Main Results:
- Heparin increased arterial FFA from 0.65 to 1.83 micromole/ml.
- Elevated FFA did not affect myocardial oxygen extraction at rest or during pacing.
- Increased FFA did not alter ischemic manifestations or anginal pain severity in patients experiencing angina.
Conclusions:
- Elevating arterial FFA levels does not increase myocardial oxygen demand or worsen ischemia in patients with CAD.
- Findings suggest FFA may not be a primary driver of ischemia in this population under the tested conditions.
Abstract:
To evaluate whether elevated arterial free fatty acids (FFA) increase myocardial oxygen demand and ischemia, 15 fasting patients with coronary artery disease underwent a standardized atrial pacing test before (PTI) and during (PT2) heparin infusion. The patients were monitored for clinical and electrocardiographic (ECG) manifestations of ischemia. Myocardial extraction of lactate, inorganic phosphate, oxygen and FFA was measured before and during each PT. The control arterial FFA was 0.65 +/- 0.03 micromole/ml and rose to 1.83 +/- 0.16 micromole/ml during heparin influsion. Myocardial oxygen extraction at rest and during PT was not affected by the increase in arterial FFA. Seven patients asymptomatic during PT1 did not develop ischaemic manifestations during PT2. In eight patients with angina during both PTs, increased arterial FFA concentration did not modify the severity of anginal pain, the amount of ST-segment depression and the myocardial balance of lactate or inorganic phosphate. Elevation of arterial FFA by heparin neither increased myocardial oxygen extraction at rest or during pacing nor accentuated ischemic manifestations during PT.