Intracoronary papaverine induced myocardial lactate production in patients with angiographically normal coronary arteries

Pharmacological options for inducing maximal hyperaemia during studies of coronary physiology

The coronary pressure wire is used for physiological assessment of the coronary vasculature increasingly frequently in clinical practice. Fractional flow reserve (FFR) can now be used to assess lesion severity in a variety of anatomical situations. Increasingly, the coronary pressure wire is being used to interrogate the coronary microvasculature. Coronary flow reserve (CFR) and Index of microcirculatory resistance (IMR) require hyperaemia to accurately assess thermodilution-derived mean transit times, and pressure derived collateral flow index (CFIp) is calculated from coronary wedge pressure and aortic pressure at hyperaemia. In addition, coronary flow velocity as assessed by a coronary Doppler flow wire needs appropriate induction of hyperaemia. However, the majority of this article will however focus on hyperaemia induction for pressure wire studies particularly FFR. Significant clinical decisions are made as a result of FFR readings, therefore it is imperative that they are carried out correctly. Maximal coronary hyperaemia is essential in producing accurate, reproducible measurements. This article focuses on the pharmacological agents that can be used for this purpose, discusses which agents can be used in specific situations, and briefly addresses the future of pharmacological stress in the catheter laboratory.

Safety and optimal dose of intracoronary adenosine 5'-triphosphate for the measurement of coronary flow reserve

BACKGROUND

Adenosine 5'-triphosphate (ATP) has been demonstrated to have similar vasodilator potency and fewer hemodynamic or electrocardiographic derangements compared with papaverine in the measurement of coronary flow reserve. However, there is little data about its optimal dose and the effect on myocardial lactate metabolism.

METHODS

Under continuous monitoring of the left anterior descending coronary flow velocity with a Doppler guide wire, we investigated the changes of hemodynamics, electrocardiogram, and myocardial lactate metabolism before and after the administration of 50 microg ATP and 10 mg papaverine into the left coronary artery in 18 patients with normal coronary arteries. To determine the optimal dose of ATP for the coronary flow reserve in the left coronary artery, we measured coronary flow velocity with five incremental doses of intracoronary ATP (0.5, 5, 15, 30, and 50 microg) and 10 mg of papaverine in another seven patients.

RESULTS

In contrast to papaverine, ATP did not produce any significant changes in hemodynamics or the electrocardiogram. The increase in the coronary flow velocity of the two agents was similar. Although all patients showed lactate production after the administration of papaverine, only three patients showed lactate production after ATP (p < 0.001). The coronary flow reserve derived from > or = 215 microg of ATP was similar to that derived from papaverine. There was a significant correlation between the coronary flow reserve obtained with > or = 5 microg of ATP and that obtained with papaverine.

CONCLUSIONS

These results suggest that maximal coronary vasodilation in the left coronary artery can be safely obtained with doses > or = 15 microg of intracoronary ATP in patients with normal coronary arteries.