Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians.
A 72-year-old man is evaluated for fatigue and dyspnea. Over the last several months to a year, he has had increasing fatigue, exercise intolerance, and dyspnea on even mild exertion. He becomes short of breath walking across a room, although he is asymptomatic at rest. He denies chest pain, palpitations, syncope, orthopnea, and lower extremity edema. He has a history of coronary artery disease, with a myocardial infarction and four-vessel coronary artery bypass graft surgery 4 years ago. He also has hyperlipidemia and type 2 diabetes mellitus. Medications are aspirin, low-dose carvedilol, lisinopril, digoxin, spironolactone, furosemide, pravastatin, and glyburide.
On physical examination, his blood pressure is 92/57 mm Hg, pulse is 57/min, and respiration rate is 12/min. Cardiovascular examination reveals a point of maximal impulse that is displaced laterally. Rhythm is regular and bradycardic. S1 and S2 are normal, with a grade 2/6 to 3/6 holosystolic murmur at the apex. An S3 is present. Estimated central venous pressure is 8 cm H2O; there is no hepatojugular reflux. The lungs are clear. There is no ascites. The liver edge is palpable 1 cm below the right costal margin. The lower extremities are warm with decreased distal pulses bilaterally. There is no ankle edema.
Electrocardiogram demonstrates sinus rhythm with a rate of 55/min. PR interval is 180 msec, QRS width is 180 msec, and QT interval is 380 msec. Left bundle branch block is seen. A dobutamine stress echocardiogram reveals a left ventricular ejection fraction of 33% with a large anteroapical area of akinesis and no ischemia.
Which of the following is the most appropriate management option for this patient?
A) Add amiodarone
B) Biventricular pacemaker-defibrillator
C) Dual-chamber pacemaker
D) Implantable defibrillator
MKSAP Answer and Critique
The correct answer is B) Biventricular pacemaker-defibrillator. This item is available to MKSAP 15 subscribers as item 5 in the Cardiology section.
MKSAP 16 released Part A on July 31. More information is available online.
This patient has worsening heart failure symptoms (New York Heart Association [NYHA] class III) despite a good heart failure medication regimen. In addition, he has an increased risk of sudden death due to ischemic cardiomyopathy. Implantation of a biventricular pacemaker-defibrillator may afford him both symptomatic benefit and a reduced risk of death. The indications for biventricular pacemaker-defibrillator placement include NYHA class III or IV heart failure, an ejection fraction less than or equal to 35%, and a QRS width greater than 120 msec. Approximately 70% of patients who undergo biventricular device placement obtain a symptomatic benefit, thought to result from mechanical “resynchronization” of the timing of right and left ventricular contraction. These devices have been shown to improve ejection fraction, quality of life, and functional status, as well as to decrease heart failure hospitalizations and mortality.
Amiodarone does not improve symptoms of heart failure or decrease mortality and therefore would not be of use in this patient.
This patient is a candidate for an implantable defibrillator for prevention of sudden death. However, a single-lead primary prevention device will not provide amelioration of his symptoms. A dual-chamber (atrioventricular) pacemaker-defibrillator would provide additional protection from sinus bradycardia by atrial pacing, while the defibrillator portion would reduce his risk of sudden death. Although a conventional dual-chamber pacemaker may allow increases of β-blocker dosage, there is no evidence that such a strategy results in improved cardiovascular outcome in patients treated for heart failure and it will not by itself provide symptomatic benefit or protect the patient from ventricular arrhythmia and sudden death. Additionally, some dual-chamber defibrillators oblige right ventricular pacing, which can cause worsening of heart failure symptoms and increase hospitalization for heart failure.
Key Point
- A biventricular pacemaker-defibrillator may provide symptomatic and mortality benefit in patients with ejection fraction less than or equal to 35%, QRS width greater than 120-130 msec, and New York Heart Association class III or IV heart failure.
Learn more about ACP’s MKSAP 16.
This content is excerpted from MKSAP 15 with permission from the American College of Physicians (ACP). Use is restricted in the same manner as that defined in the MKSAP 15 Digital license agreement. This material should never be used as a substitute for clinical judgment and does not represent an official position of ACP. All content is licensed to KevinMD.com on an “AS IS” basis without any warranty of any nature. The publisher, ACP, shall not be liable for any damage or loss of any kind arising out of or resulting from use of content, regardless of whether such liability is based in tort, contract or otherwise.
