Myocardial release of citrate and lactate during atrial pacing-induced angina pectoris

Abstract

Arterio-coronary sinus (A-Cs) differences of plasma citrate, glucose, free fatty acids and blood lactate were measured in 19 patients with coronary artery disease (CAD) and in eight control subjects exposed to atrial pacing. Among patients with CAD 11 showed a myocardial release of lactate during pacing (lactate producers, LP) while myocardial lactate extraction was unchanged in the remaining eight patients (lactate non-producers, LNP). In patients with CAD, (A-Cs) plasma citrate differences became increasingly negative during recovery from pacing, values at rest and at 3—5 min of recovery were: −5.2 μmol/l (mean±SD) vs. −12.5 μmol/l in LP (P<0.001) and −6.3 μmol/l vs. −8.4 μmol/l in LNP (P<0.01). In controls, (A-Cs) citrate difference varied inversely, from −8.4 μmol/l at rest to −2.4 μmol/l at 3—5 min of recovery (P<0.001).

An increasingly negative (A-Cs) plasma citrate difference during recovery from pacing-induced angina pectoris is suggested to reflect a wash-out of accumulated citrate from ischaemic heart cells; and is proposed as a more sensitive marker of ischaemia in man than a myocardial release of lactate.

Key Words:

• arterio-coronary sinus concentration difference
• coronary artery disease
• free fatty acids
• maximal rate-pressure product