March 27th, 2013
Left to Our Many Devices, Which One Do We Choose?
A 63-year-old male smoker with type 2 diabetes presents for the first time with chest pain and shortness of breath at rest. He has no recent history of viral infection and no family history of heart failure or sudden cardiac death.
Initial laboratory testing documents negative troponin, normal calcium, normal serum angiotensin-converting-enzyme (ACE) activity, and a negative HIV test. He has no hilar lymphadenopathy.
After being managed with intravenous diuretics and stabilized with ramipril 1.25 mg once daily and furosemide 40 mg twice daily, the patient still has significant limitations and mobilizes comfortably only around the bed. His systolic blood pressure (about 95 mm Hg) prevents the introduction of a beta-blocker. His intermittently high potassium level (up to 6.1 mmol/liter) precludes use of an aldosterone antagonist.
Electrocardiogram: left bundle-branch block, QRS duration 120 msec, and first-degree heart block (PR interval, 220 msec).
Echocardiogram: dilated left ventricle (end-diastolic diameter, 5.8 cm); LV ejection fraction, using Simpson’s biplane, of 16%; mildly dilated and significantly impaired right ventricle; elevated pulmonary artery pressure (about 50 mm Hg).
Coronary angiography: normal coronary arteries
MRI: no late gadolinium enhancement
Cardiac monitoring: periodic 2:1 heart block (<10% of the time)
All of the clinicians who considered the patient’s case agree that a device is warranted.
Which device should this patient receive as chronic therapy?
1. Dual-chamber pacemaker. The patient currently does not pace >40% of the time, and his expected progress is hard to determine. His device can be upgraded if he stabilizes in NYHA class III or better (although not according to current UK guidelines) and if optimal medication does not improve his left-ventricular function.
2. Cardiac resynchronization therapy–pacemaker (CRT-P) device. The patient’s ventricular function is poor and is unlikely to recover significantly. Furthermore, his conduction disease will progress, and he is likely to become dependent on pacing during the lifetime of the device. Given that he is arguably still in NYHA class IV, albeit ambulatory, he is currently not eligible for a defibrillator.
3. CRT–defibrillator (CRT-D) device. The patient is improving and with good medical therapy is likely to improve further. He has very poor ventricular function, and his conduction disease raises the possibility of a laminopathy, further increasing his risk level.
4. Another option
April 11, 2013
This patient has several worrisome clinical features, including advanced symptoms despite maximal tolerated therapy, the inability to titrate to target doses of heart-failure medications, pulmonary hypertension, and conduction-system disease. In light of these issues, it is not clear to me that he is “likely to improve further.” Ivabradine is not available in the U.S. but could be considered to augment his modest medical therapy without risking exacerbation of his atrioventricular (AV) block.
I do agree that device therapy is indicated (and guideline supported) in this situation; in fact, device therapy may enable initiation of beta-blockade, which the patient’s current AV block (but not his BP) does not permit. Notably, device therapy provides a “bridge” to advanced therapies, as the natural history of this patient is likely to be inexorable progression of heart failure. The worrisome 2:1 AV block with a baseline left bundle-branch block also requires dual-chamber pacing, preferably biventricular (e.g., with a cardiac resynchronization therapy–defibrillation device).
A Lyme titer should be checked if the patient’s history warrants it. There is little circumstantial evidence for sarcoid, despite the AV block. (Laminopathy, as noted, is a good thought as well and would be supported by a family history.)
April 18, 2013
We implanted a cardiac resynchronization therapy–pacemaker device with a high-voltage lead in the right ventricle. In the UK, the use of implanted cardioverter–defibrillators (ICDs) for a dilated cardiomyopathy is still much debated. NICE guidelines are expected to clarify the issue in 2014. We have referred the patient for genetic testing for a laminopathy and have tested him for Lyme serology (it is not something we usually overlook in the rural area where I practice).
When I examined the patient very recently, his clinical presentation was, perhaps surprisingly, much better. He walked up four flights of stairs to the cardiology clinic, although he was breathless at the top. He now takes ramipril 2.5 mg daily, and his blood pressure remains below 100 mm Hg. He is keen to go back to work (as a machine operator).
I will see him again in 2 months, when I will order a repeat echocardiogram to assess remodeling. He and I talked about the option of an upgrade to an ICD, but he is concerned about possible effects on his employment and about the (perhaps) increased risk for interactions between the ICD and the machines he operates at work.