A 75-year-old man has a history of New York Heart Association Class II congestive heart failure (CHF), coronary artery disease (CAD) with coronary artery bypass graft (CABG) surgery, and aortic stenosis with a bioprosthetic aortic valve replacement (AVR). He developed second-degree heart block (Mobitz II) following his four-vessel CABG and AVR four years ago, requiring placement of a dual-chamber pacemaker.
He has been asymptomatic and plays golf two to three times per week. One week ago, he went to an urgent care center for treatment of a laceration on his leg and was told that part of his pacemaker wasn’t working. He presents to you now for follow-up on the pacemaker.
Medical history is also remarkable for COPD, left inguinal hernia repair, hyperlipidemia, and bilateral cataracts. Family history is positive for CAD, diabetes, and stroke. He has a remote history of smoking and drinks one martini after each golf game. His medications include aspirin, lovastatin, and metoprolol. He has no drug allergies. The review of systems is negative except for a recent repair to a 3-cm laceration on the left leg.
Physical examination reveals a well-developed, pleasant man in no distress. His height is 74” and weight, 179 lb. Blood pressure is 118/84 mm Hg; pulse, 80 beats/min and regular; respiratory rate, 14 breaths/min; temperature, 98.8°F; and O2 saturation, 97% on room air.
Pertinent physical findings include a well-healed pacemaker site without signs of recent trauma. The lungs are clear in all fields, the cardiac exam is within normal limits, and there is no jugular venous distention. The abdomen is benign, and there is no peripheral edema. The laceration repair on his left leg is healing well (no erythema, induration, wound separation, or dehiscence). The pacemaker is programmed DDD at a lower rate of 60 beats/min and an upper rate of 120 beats/min, with paced and sensed atrioventricular (AV) delays programmed at 130 ms.
An ECG reveals the following: a ventricular rate of 83 beats/min; PR interval, not measured; QRS duration, 162 ms; QT/QTc interval, 480/564 ms; P axis, unmeasurable; R axis, 254°; and T axis, 56°. What is your interpretation of this ECG? Is there any indication that the pacemaker is not functioning?