Background Proposed mechanisms for "warm-up" after angina on first exercise
include ischemic preconditioning and collateral recruitment. The aim of th
is study was to determine whether patients with ischemic heart disease and
well-developed coronary collateral vessels have a greater warm-up response
than those with no visible collateral vessels.
Methods and Results Fifteen patients with a total coronary occlusion and co
llateral vessels and 18 patients with a single coronary artery stenosis and
no angiographically visible collateral vessels were studied. Warm-up was m
easured as the difference in ST depression on the second compared with the
first of 2 sequential treadmill exercise tests separated by 10 minutes of r
est. There was a trend for the duration of second exercise to increase more
in patients with occlusion than in those with stenosis (+1.3 vs +0.54 minu
tes, respectively, P = .087). In both groups, ST depression was less on sec
ond exercise than on first exercise. The size of this decrease was greater
in the occlusion group than in the stenosis group. ST depression at equival
ent submaximal exercise decreased by 0.52 vs 0.19 mm, respectively (P = .04
9). The rate of increase in Si depression during exercise decreased by 1.08
versus 0.55 mm/min, respectively (P = .034). These differences were less a
fter adjustment for ST depression on first exercise (P = .11 and P = .063,
respectively).
Conclusions The trend for a greater decrease in ST depression on second com
pared with first exercise in the patients with total coronary occlusion sug
gests that an increase in collateral flow is a mechanism for warm-up after
first exercise in ischemic heart disease.