Rythmonorm is used to treat arrhythmias and to maintain a normal heart rate. It acts on the heart MUSCLE to improve the heart's rhythm not the electrophysiological system. It is contra-indicated for individuals with a low EF (amt. of blood pumped with each heartbeat).
It can harm heart muscle and for some insight: "Of the patients with congestive heart failure probably related to RYTMONORM, 80% had preexisting heart failure and 85% had coronary artery disease. CHF attributable to RYTMONORM developed rarely (< 0.2%) in patients who had no previous history of CHF. As RYTMONORM exerts both beta blockade and a (dose-related) negative inotropic effect on cardiac muscle, patients with congestive heart failure should be fully compensated before receiving RYTMONORM.
During treatment with oral propafenone in patients with depressed baseline function (mean EF=33.5%), no significant decreases in ejection fraction were seen. In clinical trial experience, new or worsened CHF has been reported in 3.7% of patients; of those 0.9% were considered probably or definitely related to RYTMONORM".
Thanks for your question, and if you have any followup you are welcome to respond. Take care.
It's an antiarrhythmic drug, and it can have side effects, but I doubt it will harm the heart as a muscle. I can't give specific advice about meds, you'll have to ask a doctor, but I know this type of drugs sometimes causes electrical imbalances that can cause arrhythmias (a bit ironic, because the purpose is to prevent them).
Anyway, it's really depending on previous EKG findings. If your doctor didn't think you could handle this medication, I doubt he would have prescribed it.