Antonio Lopez-Farre, Carlos Macaya and colleagues at Clinico Hospital San Carlos in Madrid used a powerful technology called two-dimensional electrophoresis to study changes in different proteins present in two groups of patients with coronary artery disease, the underlying cause of most heart attacks.

One group of patients was aspirin-sensitive and the other had aspirin resistance.

The researchers found increased levels of three proteins involved in the binding of vitamin D in patients with aspirin resistance. They also demonstrated those proteins can inhibit aspirin's effects in preventing blood clots.

The researchers said their findings might aid in the development of more effective therapies for aspirin-resistant patients.

The study is scheduled for publication in the July 6 issue of the Journal of Proteome Research,