What is the incidence of ventricular tachycardia (V Tach) in patients on long-term Pletal (Cilostazol) therapy?

Ventricular Tachycardia Risk with Long-Term Cilostazol (Pletal) Use

Cilostazol is contraindicated in patients with heart failure due to its potential to trigger ventricular tachycardia, though the exact incidence of V-tach in long-term users without heart failure is not precisely quantified in current literature. 1

Mechanism of V-Tach Risk with Cilostazol

• Cilostazol is a phosphodiesterase III (PDE III) inhibitor that increases intracellular cyclic AMP, which is the mechanism believed to account for both its vasodilatory effects and its potential to trigger ventricular tachycardia 1
• The FDA drug label specifically notes that in clinical studies, more cilostazol-treated patients had increases in ventricular premature beats and non-sustained ventricular tachycardia events compared to placebo-treated patients, though these increases were not dose-related 2
• The chronotropic effects of cilostazol are well-documented, with studies showing significant increases in heart rate by a mean of 5.1 and 7.4 beats per minute in patients treated with 50 and 100 mg twice daily, respectively 2

Documented Side Effects Related to Arrhythmias

• Palpitations and tachycardia are among the common side effects reported with cilostazol use 1
• In a randomized comparison study using 24-hour Holter monitoring, patients on triple antiplatelet therapy including cilostazol had significantly higher 24-hour heart rates compared to those on dual antiplatelet therapy without cilostazol (73 vs. 68 bpm, p<0.001) 3
• The same study found that cilostazol use was a strong predictor (OR: 3.10, p=0.035) of heart rate increases ≥5 bpm, though there were no significant differences in arrhythmia occurrence 3

Case Reports and Special Considerations

• There is at least one documented case report of a 92-year-old woman with normal systolic function who developed ventricular tachycardia two days after starting cilostazol, with resolution after discontinuation of the medication 4
• Paradoxically, some research suggests cilostazol may have beneficial effects in preventing ventricular fibrillation in specific patient populations such as those with Brugada syndrome, suggesting its cardiac effects may be complex 5

Contraindications and Monitoring

• Cilostazol is absolutely contraindicated in patients with heart failure of any severity due to the increased risk of ventricular tachycardia 1, 6
• Regular cardiac monitoring is recommended for patients on long-term cilostazol therapy, with particular attention to the development of new cardiac symptoms 6
• Approximately 20% of patients discontinue cilostazol within the first 3 months due to side effects, including cardiovascular effects 1, 6, 7

Clinical Implications and Recommendations

• For patients requiring long-term cilostazol therapy, evaluate tolerance at 2-4 weeks after initiation and assess clinical benefit within 3-6 months 1, 6
• Consider discontinuation if patients develop new cardiac symptoms, particularly palpitations or symptoms suggestive of arrhythmias 6
• Patients with risk factors for arrhythmias should be monitored more closely when on cilostazol therapy 6
• The American College of Cardiology/American Heart Association guidelines emphasize that cilostazol should not be administered to patients with congestive heart failure of any severity 1

While the exact incidence of ventricular tachycardia with long-term cilostazol use is not precisely quantified in the current literature, the risk is recognized in clinical guidelines and FDA labeling, particularly for patients with heart failure.