Pulmonary Embolism (PE): Although sinus bradycardia is not a typical finding in PE, the combination of chest pain and bradycardia, especially in an older adult, warrants consideration of PE due to its high mortality if missed. The right-sided chest pain could be indicative of a peripheral PE.

Acute Coronary Syndrome (ACS): While ACS typically presents with left-sided chest pain, right-sided pain can occur, especially with inferior wall myocardial infarctions. The presence of sinus bradycardia might be seen in the context of an inferior MI due to the involvement of the right coronary artery, which also supplies the AV node.
Pneumonia or Pleuritis: Infections such as pneumonia or inflammatory conditions like pleuritis can cause right-sided chest pain. Sinus bradycardia might be seen in response to severe pain or as part of the systemic inflammatory response.
Gastroesophageal Reflux Disease (GERD): GERD can cause chest pain that might be perceived as right-sided and can sometimes be associated with bradycardia, although this is less common.

Aortic Dissection: Although typically presenting with severe, tearing chest pain that is often described as moving from the anterior to the posterior chest, an aortic dissection can occasionally present with more localized pain. The presence of bradycardia is not typical but could occur in the context of severe pain or if the dissection compromises blood flow to the heart. Missing this diagnosis can be fatal.
Pulmonary Embolism with Associated Pericarditis: If a PE is large enough, it can cause acute right heart strain, potentially leading to pericarditis, which might present with chest pain and bradycardia.
Cardiac Tamponade: This condition, characterized by fluid accumulation in the pericardial sac, can lead to impaired cardiac filling, reduced cardiac output, and potentially life-threatening complications. It might present with chest pain, bradycardia, and signs of shock.

Tietze's Syndrome: A rare condition characterized by inflammation of the cartilages and surrounding tissues of the ribs, which can cause chest pain and might be associated with bradycardia due to pain-induced vagal response.
Pneumothorax: While typically presenting with acute onset of sharp chest pain and shortness of breath, a small pneumothorax might have a more subtle presentation, including right-sided chest pain and potentially bradycardia if the patient is experiencing significant pain or anxiety.