Stress test with dual isotope studies for the documentation of classical ischemic preconditioning
Received 28 September 2009; received in revised form 27 October 2009; accepted 25 November 2009. published online 04 January 2010.
Abstract
Objectives
We investigated whether myocardial perfusion imaging (MPI) can demonstrate the effect of classical preconditioning.
Methods
21 patients with documented coronary artery disease (stenosis≥70%) underwent two exercise stress tests (EST) with concomitant MPI, using TL-201 for the first and tetrofosmin-Tc-99m for the second. A third MPI was performed at rest, using Tc-99m. Total defect score was derived by summing tracer uptake in a 17 segments left ventricle model, graded on a 5-point scale. Tomographic images were also analyzed quantitatively, to derive the total defect size.
Results
Maximum ST depression did not differ significantly between the two EST (2.2±1 vs 2.2±1mm, p=NS), however in the second EST longer times for onset of ischemic changes (228±94 vs 265±103s, p=0.01) and appearance of angina (282±153 vs 328±177s, p=0.04) were observed. Exercise perfusion abnormalities were significantly lower in the second MPI, in terms of both total defect score (19.2±11.5 vs 10±10.4, p<0.0001) and total defect size (28.3±16.9 vs 13.8±15.8, p<0.0001).
Conclusion
Significant improvement in perfusion pattern was demonstrated in the second MPI, accompanied by delayed appearance of ischemic manifestations. The improvement in myocardial perfusion extends far beyond the changes that can be attributed to differences in myocardial uptake between tracers, reflecting the effect of classical preconditioning.
ABSTRACT