The effects of Ramadan fasting on patients with prosthetic heart valve taking warfarin for anticoagulation

Oral anticoagulation with warfarin is indicated for patients with prosthetic heart valves. The effects of religious fasting during Ramadan month (in the Islamic calendar) on anticoagulation aren't clear.

To study the impact of Ramadan fasting on international normalized ratio (INR), quality of anticoagulation, dose of warfarin used and blood osmolarity.

18 patients were followed-up prospectively for 3 months (pre- Ramadan, Ramadan and post-Ramadan months). Patients presented for weekly visits in which blood samples were obtained.

No significant difference in INR and warfarin dose was found between Ramadan month, and months before and after it. The post-Ramadan INR was significantly larger than pre-Ramadan (p = 0.004). Blood osmolarity was significantly lower during Ramadan compared to pre- and post-Ramadan months. A significantly better quality of anticoagulation was noticed during Ramadan (p < 0.001). A significantly larger ratio of supratherapeutic INR values occurred in the post-Ramadan month (p < 0.05). A significantly larger ratio of infra-therapeutic INR values was noticed in the pre-Ramadan month (p < 0.05).

No significant difference in mean INR or warfarin dose was found and a better quality of anticoagulation was achieved during Ramadan. A tendency toward supra-therapeutic anticoagulation occurred after Ramadan, thus a closer follow up during this period may be reasonable.