Good day, it is safe to take Claritin with your medication despite your arrhythmia problems. However, I would recommend consulting an allergist to explore other treatments such as nasal spray, eye drops, or desensitization. Additionally, long-term use of allergy medications such as Claritin can sometimes make them less effective, so it may be beneficial to switch to another allergy medication if this occurs. Lastly, it is best to take a medication for the shortest time possible, so it may be beneficial to try desensitization or to stay away from identified allergens as much as possible instead of taking Claritin all year round.