Temporal Relationships of Myocardial Lactate Metabolism, Left Ventricular Function, and S-T Segment Depression During Angina Precipitated by Exercise
Why the study?
How do myocardial lactate metabolism, left ventricular function, and S-T segment depression temporally relate during angina precipitated by exercise in patients with coronary artery disease?
Population
14 patients, including 12 with coronary artery disease and 2 normal subjects.
Comparison
Supine leg exercise with continuous monitoring… vs Baseline and comparison between patient subgroups.
Design
Cohort
Authors
Discussion
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Implication
Impaired lactate extraction during exertional angina coincides with LVEDP rise and ST depression; cohort data leave open causal mechanisms in CAD.
Key Points
- To evaluate the temporal relationships connecting myocardial lactate metabolism, left ventricular mechanical function, and ST segment depression during exercise-induced angina.
- Monitored 14 participants (12 with coronary artery disease and 2 normal controls) before, during, and after supine leg exercise.
- Concurrently measured continuous electrocardiography, left ventricular end-diastolic pressure, stroke work, and arterial and coronary sinus lactate concentrations.
- Myocardial lactate extraction increased to 36.7% in normal subjects and 28.5% in non-angina coronary patients during exercise, but only increased to 8.8% in patients developing angina (with 2 patients exhibiting net lactate production).
- Left ventricular end-diastolic pressure consistently rose during angina in close temporal synchrony with ST segment depression, while stroke work remained unchanged despite increased filling pressures.
- High arterial lactate accumulation during exercise obscured direct metabolic evidence of myocardial ischemia despite distinct hemodynamic and electrocardiographic changes.
Structured PICO
How do myocardial lactate metabolism, left ventricular function, and S-T segment depression temporally relate during angina precipitated by exercise in patients with coronary artery disease?
P
Population
14 patients, including 12 with coronary artery disease (7 with exertional angina, 5 without pain) and 2 normal subjects.
I
Intervention
Supine leg exercise with continuous monitoring of myocardial lactate metabolism, electrocardiogram, and left ventricular function.
C
Comparator
Baseline (before exercise) and comparison between patient subgroups (angina vs. non-angina vs. normal subjects).
O
Outcome
Changes in myocardial lactate metabolism (arterial and coronary sinus lactate concentrations, lactate extraction), left ventricular function (end-diastolic pressure, stroke work), and S-T segment depression.surrogate
Exertional angina is closely correlated with S-T segment depression and elevated left ventricular filling pressures, indicating impaired contractility, though systemic lactate increases during exercise obscure local metabolic evidence of ischemia.
Limitations
- Elevated arterial lactate concentrations obscured the ability to relate exertional angina, S-T segment depression, and hemodynamic abnormalities to metabolic evidence of ischemia.
Cite This Study
Parker et al. (1969) studied this question.