The positive relationship between insulin resistance and cardiovascular disease, including angina pectoris, has been studied extensively. Troglitazone, which reduces insulin resistance, is thought to decrease clinical manifestations of coronary vasospastic angina pectoris. Murakami and associates evaluated the effectiveness of troglitazone in decreasing anginal episodes in patients with diabetes mellitus.

Ten patients with diabetes who had a history of spontaneous or provoked coronary vasospasm and residual angina pectoris were enrolled in the study. Coronary vasospastic angina pectoris was defined as angina pectoris with angiographically demonstrated (spontaneous or acetylcholine-provoked) coronary spasm. Patients with fixed organic stenosis or those receiving insulin were excluded from the study. Patients received troglitazone in a dosage of 400 mg per day for four months. Changes in anginal episodes were measured at baseline and at four months by counting the number of episodes per month, the duration of each episode and the number of self-administered sublingual nitrates. Reactive changes in the lumen diameter of the right brachial artery following transient occlusion for five minutes were measured by two-dimensional ultrasonography (flow-mediated endothelium-dependent vasodilatation) and after administration of sublingual glyceril trinitrate at baseline and at four months.

The number and duration of anginal episodes were significantly reduced after medication. The use of sublingual nitrates also tended to decrease after medication. Flow-mediated endothelium-dependent vasodilation improved after medication, correlating with the reduction in episode duration. There were no adverse effects associated with troglitazone use.

The authors conclude that troglitazone decreases the number and duration of anginal episodes in patients with diabetes who have coronary vasospastic angina pectoris. However, its exact mechanism of action is not clearly understood. One plausible explanation is that the decrease in anginal episodes may be associated with improvement of the dysfunctional endothelium-dependent vasoreactivity that is linked to insulin resistance.