Hi & Welcome. I can understand your concern. Toprol-XL (Metoprolol) & Atenolol are beta blockers are known to cause slow heart beats to the extent of causing syncope or hearrt block, decreased circulation to the tissues resulting in fatigue, body ache, etc and difficulty in breathing in patients with air way diseases like asthma, or bronchitis. Most people with premature ventricular contractions (PVCs) don t need treatment except for avoiding coffee and cigarettes. However if you have frequent, bothersome symptoms, you may be offered treatment by other medications such as calcium channel blockers (Diltiazem) or anti-arrhythmic drugs such as Amiodarone. So, consult your cardiologist for an alternate but a safer medication for PVCs. Hope this answers your query. A feedback is appreciated.