[Isosorbide-5-mononitrate in silent ischemia]

Area of Science:

• Cardiology
• Pharmacology
• Ischemic Heart Disease

Background:

• Coronary artery disease (CAD) frequently involves exercise-induced silent ischemia.
• Silent ischemia, particularly during exercise, poses a significant risk for cardiovascular events.
• Nitrate therapy is a common treatment for ischemic heart disease.

Purpose of the Study:

• To evaluate the efficacy of sustained-release isosorbide-5-mononitrate (IS-5-MN) in managing exercise-induced and ambulatory silent ischemia.
• To assess the impact of once-daily 60 mg IS-5-MN on ischemic episodes in patients with documented CAD.

Main Methods:

• A double-blind, randomized, placebo-controlled crossover study involving 36 patients with CAD and exercise-induced silent ischemia.
• Patients underwent symptom-limited bicycle exercise tests and 24-hour Holter monitoring.
• Treatment periods included a wash-out phase, a one-week IS-5-MN treatment, and a one-week placebo treatment.

Main Results:

• IS-5-MN significantly prolonged the time to 1 mm ST-segment depression during exercise testing (p < 0.05).
• The number and circadian variation of ischemic episodes during Holter monitoring were not significantly affected by IS-5-MN.
• A discrepancy was observed between improved exercise-induced ischemia and unchanged ambulatory ischemia.

Conclusions:

• Once-daily 60 mg IS-5-MN effectively improved exercise-induced silent ischemia in CAD patients.
• IS-5-MN did not demonstrate significant benefits for ambulatory silent ischemia, suggesting different underlying mechanisms.
• The study highlights potential limitations of fixed-dose nitrate therapy in completely suppressing all forms of silent ischemia.