The investigators will investigate patients undergoing coronary angiography with normal coronary but slow blood flow that was normalized after adenosine injection into the coronary artery. The investigators believe that they have small vessel coronary disease which is the initial presentation of coronary disease prior to anatomical narrowing. To alleviate this phenomenon the investigators intend to examine the long-term clinical response of these patients to treatment with dipyridamole, a well-known medication with almost no side-effects that increases the level of adenosine in the tissue.

Inclusion Criteria:

• Patients undergoing coronary angiography and who have normal coronary artery with slow blood flow that normalized with adenosine injection into the coronary artery

Exclusion Criteria:

• Significant coronary disease
• Unstable patients
• Patients with known sensitivity to dipyridamole