Magnetic resonance contrast enhancement with gadolinium-DTPA in patients with angina and angiographically normal coronary arteries: effect of chronic beta-blockade.

BACKGROUND

The syndrome of angina and normal coronary arteries (syndrome X) comprises a heterogeneous group of patients with typical chest pain, a positive exercise test, angiographically smooth coronary arteries and no evidence of spasm. Magnetic resonance imaging (MRI) has been used to detect areas of myocardial ischemia and/or recent necrosis both in animal and human studies. Most of these studies have been conducted after intravenous administration of the paramagnetic contrast medium gadolinium-DTPA (Gd-DTPA), that is considered a sensitive marker of extracellular, probably ischemic in origin, edema. On the basis of these data, we used MRI to evaluate the possibility of myocardial Gd-DTPA deposition at rest in patients with syndrome X, and to assess the effects of oral treatment with atenolol.

METHODS

We have studied 24 patients with syndrome X, 10 patients with coronary artery disease and 10 age-matched control subjects. The protocol was similar in all study subjects. Exercise testing and MRI were undertaken off therapy after coronary arteriography. Following MRI, patients underwent a 10 day treatment period with atenolol and repeated exercise stress test and MRI while on therapy.

RESULTS

In all patients with syndrome X and coronary artery disease were observed effort diagnostic ST-segment changes that were associated with angina in 9 (37%) and 7 (70%) patients, respectively. Of 24 patients with syndrome X, 16 (66.6%) showed areas of myocardial enhancement after Gd-DTPA in comparison to the precontrast imaging. In 4 out of 10 patients with coronary artery disease (40%), Gd-DTPA accumulation was documented. Finally, focal Gd-DTPA myocardial enhancement was not observed in any normal control subject. After beta-blockade, 22 (92%) patients with syndrome X and 2 (20%) with coronary artery disease did not show any ischemic ST-segment changes on effort; 14 syndrome X patients (88%) and 2 coronary artery disease patients (50%) showed complete disappearance of the previously Gd-DTPA enhanced areas on MRI.

CONCLUSIONS

Patients with syndrome X often exhibit regional accumulation of Gd-DTPA on MRI. The agent is believed to trace interstitial water accumulation as occurs during ischemia and its accumulation is reduced or abolished by treatment with atenolol, probably by different mechanisms. It is likely that an overactivation of the sympathetic outflow to the cardiovascular system can induce most of the abnormalities observed in syndrome X patients. In this context, beta-blockers probably represent the mainstay of the medical treatment of this condition.