Background: The effects of fibrillation/defibrillation episodes (FDEs) duri
ng defibrillator implantation on myocardial metabolism were investigated at
various defibrillation energies in patients with different cardiac patholo
gies. Methods: Myocardial lactate extraction (MLE) was examined during defi
brillation threshold (DFT) testing in patients with either coronary artery
disease (CAD, n = 20) or non-ischemic cardiomyopathy (CM, n = 10). Defibril
lation pulses were released 15 seconds after induced fibrillation. A test c
ycle of four FDEs separated by 2-minute intervals was applied in each case.
Results: Mean MLE decreased significantly from 28+/-4% before FDEs to 8+/-
5% immediately after all episodes in CAD patients, but recovered to 27+/-7%
within 2 minutes even in patients with reduced left-ventricular function.
In patients with CM mean MLE decreased markedly from 29+/-3% to -11+/-3% im
mediately after each FDE but increased to baseline (33+/-8%) within the rec
overy period. MLE changes were independent of defibrillation energy in all
cases. Conclusions: Myocardial lactate production, suggesting cardiac ische
mia, was observed in patients with CM, but not in patients with CAD. But re
covery of myocardial lactate extraction was not faster in CAD patients, ind
icating that the fixed FDE cycle used was well tolerated by all patients.