A 72-year-old man from Mumbai with a history of hypertension and diabetes presents with recurrent episodes of syncope over the past 3 months. ECG shows a PR interval of 280 ms with a QRS duration of 120 ms. During continuous cardiac monitoring, a 4-second pause is documented before spontaneous resumption of sinus rhythm. Echocardiography shows normal ventricular function and no structural abnormalities. What is the most appropriate next step in management?