A coronary angiogram at Tam Anh General Hospital District 8 revealed a narrowing at the site of Mr. Hung’s previous stent, reducing blood flow to his heart muscle. A new blood clot had formed, causing severe chest pain.

Despite adhering to his medication regimen and managing his underlying cardiovascular risk factors, Mr. Hung still developed a blood clot that blocked the artery. Suspecting drug resistance, Dr. Ngo Tran Quang Minh, Medical Director and Head of the General Internal Medicine Department, ordered a CYP2C19 gene test to assess Mr. Hung's responsiveness to the antiplatelet drug clopidogrel. The test confirmed that he carried a gene variant that impaired the metabolism of the drug into its active form.

Dr. Minh explained that clopidogrel is a prodrug that requires metabolization by the CYP2C19 enzyme in the liver to become an active antiplatelet agent. Platelets, when activated, can clump together and form blood clots within blood vessels. In individuals with this CYP2C19 gene variant, the activation process is incomplete, rendering the drug less effective or even completely ineffective. This leaves patients at risk of blood clot formation and recurrent blockages.

Dr. Quang Minh examining Mr. Hung. Photo: *Tam Anh General Hospital District 8*

Dr. Minh prescribed ticagrelor, a newer-generation antiplatelet medication that doesn't rely on liver enzymes for activation and offers more consistent efficacy. He also adjusted Mr. Hung’s treatment plan to include medication for cholesterol management and blood pressure control. Given Mr. Hung’s history of mild gastritis, the doctor selected medications to protect the stomach lining and avoid interactions that could reduce the effectiveness of his heart medications.

A month later, at his follow-up appointment, Mr. Hung reported no chest pain, his heart rate was stable, his liver and kidney function were normal, his cholesterol levels were well-managed, and there were no signs of re-blockage.

Cardiovascular patients often have other risk factors, such as high blood pressure, diabetes, and high cholesterol. If not properly managed, these factors can contribute to the growth of plaque in the arteries, increasing the risk of plaque rupture and blood clot formation, leading to recurrent blockages.

Dr. Minh emphasized that the effectiveness of antiplatelet drugs varies among individuals and depends on genetic factors, underlying medical conditions, and other medications being taken. He recommends regular check-ups, blood tests, and CYP2C19 gene testing before starting or during antiplatelet therapy as directed. This allows doctors to personalize treatment plans, selecting the most appropriate medication and optimal dosage.

Trong Nghia

*The patient's name has been changed.