Final answer:
Beta-blockers are inappropriate for a patient with sinus brady and a first-degree AV block, as they may worsen the condition.
Step-by-step explanation:
Given a patient with sinus brady and a first-degree AV block, beta-blockers would be inappropriate to use. These drugs, including metoprolol and propranolol, decrease the heart rate and myocardial contractility, which can exacerbate bradycardia and AV block. Instead, the patient may require a pacemaker to regulate the heart rhythm if pharmacological intervention is not suitable.
First-degree AV block indicates a delay in conduction between the SA and AV nodes, resulting in an abnormally long PR interval on an ECG. Since AV blocks are a result of issues with conduction, drugs that further slow down conduction through the AV node would be inappropriate. Therefore, drugs that block potassium channels like amiodarone and procainamide would be inappropriate to use in this patient.