History
In March 2012 this 68-year-old male patient sought treatment for chest pain. Non–ST segment elevation myocardial infarction (NSTEMI) was diagnosed, and, on catheterization, the patient was found to have severe three-vessel disease. This was unsuitable for percutaneous coronary intervention. He was therefore treated with bypass grafting and mitral valve repair.
The patient also had multiple myeloma (immunoglobulin G kappa), which was being treated with bortezimib and decadron; recurrent anemia resulting from myeloma and chemotherapy and requiring periodic blood transfusions; and thrombocytopenia. He was recommended to have platelet transfusions whenever his platelet concentration dropped below 20,000/µL or signs of bleeding occurred.
He had been previously diagnosed with mixed nonischemic and ischemic cardiomyopathy. He had a history of adriamycin exposure and thoracic radiation for myeloma. Magnetic resonance imaging 3 months previously revealed a severely dilated left ventricle (left ventricular ejection fraction [LVEF], 28%) with an akinetic inferior wall and left ventricular scar area of 9%. There was no evidence of infiltrative disease, for example, amyloidosis.
The patient had previously experienced frequent premature ventricular contractions, possibly contributing to left ventricular dysfunction. Their origin was the inferior scar margin, and they had been successfully ablated 3 months previously (December 2011). Programmed electrical stimulation at that time induced a sustained monomorphic ventricular tachycardia. In view of this, and baseline prolonged QRS duration with a left bundle branch block configuration, he received a cardiac resynchronization therapy defibrillator (CRT-D) implant (February 2012) with automatic remote monitoring capability. The implant was complicated by a significant anterior chest wall hematoma, but did not require evacuation. He had no prior history of atrial fibrillation.
The patient’s other significant comorbidities were chronic renal dysfunction, with a creatinine value normally approximately 2.0, and carotid artery disease, for which he had undergone left carotid endarterectomy in 2009.
Physical Examination
Thirty-six hours after cardiac surgery, the patient developed atrial fibrillation with a rapid ventricular response.
Laboratory Data
Postoperative Echocardiogram
On the echocardiogram a moderate pericardial effusion was seen adjacent to the right ventricle and right atrium measuring 2.3 cm and a small circumferential pericardial effusion adjacent to the left ventricle. Pleural effusions were noted bilaterally. The LVEF was 15 ±5%. The mitral valve ring had moderate (2+) mitral valve regurgitation.
Comments
An attempt was made to restore normal rhythm. Unusually, this case of postoperative atrial fibrillation was resistant to amiodarone therapy and electrical cardioversion. Sinus rhythm could not be maintained for even a few minutes.
Ideally, this patient should have been placed on anticoagulation therapy. However, this would have risked expansion of postoperative pericardial and pleural effusions in the setting of thrombocytopenia and predilection for occult bleeding. In view of this hematologic disorder, anemia, and general postoperative debilitation risking falls (requiring wheelchair), the risk to benefit balance favored postponing anticoagulation. This strategy nevertheless risked both thromboembolism and heart failure precipitated by reduction of CRT pacing level. However, because the patient had a device with remote monitoring, his condition could potentially be monitored closely without requirement for hospital visits. In particular, rate control could be optimized. The patient preferred this approach. He was discharged to a rehabilitation facility.
Follow-Up
Postoperative 2 Weeks
The patient was readmitted with decompensated systolic heart failure and continued atrial fibrillation, with ventricular rates exceeding 110 bpm (CRT pacing level <60%). He underwent thoracentesis. He was placed on diuretic therapy, and his heart failure medications were slowly optimized. This was a difficult balance in view of his systolic blood pressure of approximately 100 mm Hg. A sternal wound infection was discovered and treated with antibiotics. Tremor related to amiodarone exposure was noted.
Postoperative 4 Weeks
The patient was admitted with a chest infection, which was treated with antibiotics. He was anemic (hemoglobin 8.8 mg/dL and hematocrit 26%) and received transfusion.
FIGURE 49-1 Remote monitoring website data. Two separate panels across identical 1-month time spans (May 4 to June 4) show separate graphic parameter trends. Low cardiac resynchronization therapy (CRT) events along the top of the panels represent alert notifications automatically delivered by the remote monitoring technology. Left panel, Persistent atrial fibrillation spontaneously terminates (May 23). Right panel, Episodic dips in CRT pacing percentage are noted, from baseline levels of approximately 80%. Atrial fibrillation terminates (May 23) and then CRT pacing percentage stabilizes at approximately 98%. Atrial pacing percentage remains negligible.
Postoperative 6 Weeks
The patient received remote follow-up. This showed that he was still in atrial fibrillation, with ventricular rates at 110 bpm reducing CRT pacing to less than 60%. He was contacted, and beta blockade was increased and digoxin added for rate control.
Postoperative 8 Weeks
Figure 49-1 shows the most recent remote trends from May 2012 onward. Periods of loss of CRT pacing (see Figure 49-1, top right) were notified within 24 hours of occurrence (red arrows). These were treated promptly, resulting in resolution and gradual increase in the overall trend of the CRT pacing level over several weeks. These events were clinically silent but detected and signaled automatically by the device without patient participation and occurred irrespective of his location—his postoperative convalescence was spent alternately in skilled nursing facilities and home. Treatment could be implemented early and prevent future heart failure decompensation.
Spontaneous reversion to normal sinus rhythm occurred on May 24. The event was notified together with confirmatory electrograms (Figure 49-2, bottom). The CRT pacing level was maintained at 100% thereafter.
Focused Clinical Questions and Discussion Points
Question
Is it important to monitor atrial fibrillation in patients with CRT devices?
Discussion
Atrial fibrillation in a patient treated with CRT worsens prognosis.7 Device-detected persistent atrial tachycardia or atrial fibrillation was strongly associated with a twofold increase in the composite death or heart failure hospitalization end point. Causes involve increased thromboembolic risk (even with a duration of a few minutes) hemodynamic deterioration and heart failure, and facilitation of ventricular arrhythmias. Periods of rapid atrioventricular conduction result in withdrawal of ventricular pacing and neutralize the beneficial effect of CRT. Thus reduction in CRT pacing to less than 92% increased mortality.5 The detection and treatment of atrial fibrillation in patients on CRT is therefore important.
FIGURE 49-2
Question
How is monitoring performed for atrial fibrillation, treatment, and recurrence?
Discussion
The challenges in monitoring are in diagnosis of a silent, episodic problem, and measurement of its burden; treatment, which requires assessment of the risk to benefit ratio for appropriate anticoagulant therapy and attention to rapid ventricular responses; and monitoring to evaluate response, because patient symptoms are inaccurate and do not provide a suitable guide. Potential solutions are to schedule frequent in-clinic evaluations, which are burdensome and miss interim problems, and external monitoring, but this can be used only for short periods. However, implanted devices collect and quantify data and those embedded with remote monitoring technology enable early discovery, thus overcoming many of these barriers.4,8 In regard to atrial fibrillation, delivery of intracardiac electrograms permits confirmation of device diagnosis (mode switch data in isolation may be vulnerable to false-positive results). Continuous monitoring with daily updating of parameter trends enables accurate measurements, and automatic notification of changes facilitates early clinical management.9
Question
Should the patient receive anticoagulation therapy?
Discussion
Generally, early discovery enables early anticoagulation prescription decisions, if necessary. This may reduce thromboembolic risk.1 However, the decision to treat requires careful adjudication in each individual case. This is complicated given the different choices of measures for assessing risk from either the arrhythmia (e.g., CHADS versus CHADS VASC) or, importantly, the treatment itself (HAS-BLED versus HEMORRHAGES) cited in guidelines issued by various professional societies.2 Selection of anticoagulant becomes complicated with the recent availability of three new anticoagulants, none of which have been compared head-to-head in similar populations. Additionally, the inclusion of patient perspective on the decision is vital. A risk prediction model incorporating the several aspects of clinical decision making may permit tailored prescription of novel agents on an individual basis to achieve desired risk reductions.
Question
Is it important to monitor for rate control?
Discussion
High ventricular rates in patients on CRT are particularly important because they result in withdrawal of CRT, which removes its beneficial effect in heart failure. Even a less than 10% loss of pacing may reduce mortality by 25% to 30%. Thus, in this case, the patient had acute heart failure decompensation 2 weeks after discharge that required readmission (however, subsequent loss of CRT was rapidly rectified with the use of remote monitoring).
Several mechanisms are employed by manufacturers to promote continuous CRT delivery during atrial fibrillation. For example, each right ventricular sensed event may trigger a paced response immediately (within 10 ms) in one or both ventricles depending on how ventricular pacing is programmed.3 However, these most likely generate partially resynchronized complexes, and their efficacy is likely limited. It is therefore important to commit to pacing. This may be accomplished by restoring normal sinus rhythm if possible. For persistent atrial fibrillation, atrioventricular nodal ablation restores consistent 100% ventricular capture and has shown mortality and functional benefits.6
Final Diagnosis
The diagnosis in this patient was persistent atrial fibrillation with rapid ventricular rates in the presence of heart failure, a CRT device, and balance of risk to benefit considerations for anticoagulation that favored withholding therapy at the time of initial consultation.
Plan of Action
Immediate restoration of normal rhythm and accompanying anticoagulation were not possible; therefore a strategy of rate control was implemented with the aim of preventing rapid conducted rates and loss of CRT pacing. If medical measures were unsuccessful, atrioventricular nodal ablation would be indicated. These objectives would be followed with extended remote monitoring. If the balance of comorbidities changed in the future, anticoagulation could be reconsidered. This management strategy depended on continuous monitoring.
Intervention
Accelerated ventricular rates sporadically caused loss of CRT pacing level (see Figure 49-1). Such events are typically unsuspected by both patients and physicians, until they lead to symptomatic deterioration. Remote monitoring–derived trends revealed that the ventricular rate was usually controlled, but prone to periods of acceleration during which CRT pacing loss was further aggravated. However, these events were treated effectively. Atrioventricular nodal ablation would have been indicated if atrial fibrillation had persisted and ventricular rate accelerations had become more prolonged.
FIGURE 49-3
The case illustrates how remote monitoring–derived arrhythmia and pacing trends guided clinical decision making over a period of several months of a difficult convalescence phase with changing status of comorbidities. Parameter trending permitted close monitoring. Parameter deviations (e.g., for loss of CRT pacing level) were self-declared by the device and enabled clinical action to optimize medications within 24 hours. This preemptive care (rather than reactive to clinical decompensation) over the course of several months resulted in gradual improvement and likely avoided further heart failure decompensation and inpatient admissions. Event notification for atrial fibrillation termination with confirmatory electrograms resolved a persistent anxiety and permitted patient reassurance, stabilization of medical therapy, and correlation with clinical recovery.
Remote monitoring was continued to provide early (<24-hour) notification of atrioventricular recurrence and enable prompt cardioversion if necessary.
Outcome
Postoperative atrial fibrillation is usually reversible and self-limited, but in this case persisted for almost 3 months. Unusually, it was recalcitrant to therapy, including amiodarone (which resulted in adverse effects) and electrical cardioversion. In view of renal dysfunction and coronary artery disease, other antiarrythmics were contraindicated. Although conducted ventricular rates were eventually maintained at fewer than 90 bpm (see Figure 49-1), these occasionally were accompanied by loss of CRT pacing level. Spontaneous termination of atrial fibrillation resolved the dilemma about the necessity for atrioventricular nodal ablation and chronic anticoagulation.
Findings
No atrial fibrillation recurred, and CRT pacing has been sustained at 100% (Figure 49-3). The patient has been managed without anticoagulation and recovered well. He has resumed a physically active lifestyle.
Comments
In summary, in recipients of CRT devices, remote monitoring technology provides a high-definition image of patterns of atrial fibrillation occurrence, measurement of its daily burden, and associated ventricular rate and interaction with pacing. These data may guide clinical decision processes regarding anticoagulation and efficacy of antiarrhythmic measures undertaken, including drug therapy, ablation, and pacing systems. This ability for close monitoring is important in patients with multiple medical conditions, prone to episodic decompensations and presenting difficult management decisions.
Selected References
1. Boriani G., Santini M., Lunati M. et al. Improving thromboprophylaxis using atrial fibrillation diagnostic capabilities in implantable cardioverter-defibrillators: the multicentre Italian ANGELS of AF Project. Circ Cardiovasc Qual Outcomes. 2012;5:182–188.
2. Camm A.J., Kirchhof P., Lip G.Y. et al. Guidelines for the management of atrial fibrillation: the Task Force for the Management of Atrial Fibrillation of the European Society of Cardiology (ESC). Eur Heart J. 2010;31:2369–2429.
3. Ganesan A.N., Brooks A.G., Roberts-Thomson K.C. et al. Role of AV nodal ablation in cardiac resynchronization in patients with coexistent atrial fibrillation and heart failure: a systematic review. J Am Coll Cardiol. 2012;59:719–726.
4. Healey J.S., Israel C.W., Connolly S.J. et al. Relevance of electrical remodeling in human atrial fibrillation: results of the asymptomatic atrial fibrillation and stroke evaluation in pacemaker patients and the atrial fibrillation reduction atrial pacing trial mechanisms of atrial fibrillation study. Circ Arrhythm Electrophysiol. 2012;5:626–631.
5. Koplan B.A., Kaplan A.J., Weiner S. et al. Heart failure decompensation and all-cause mortality in relation to percent biventricular pacing in patients with heart failure: is a goal of 100% biventricular pacing necessary? J Am Coll Cardiol. 2009;53:355–360.
6. Varma N., Wilkoff B. Device features for managing patients with heart failure. Heart Fail Clin. 2011;7:215–225 viii.
7. Santini M., Gasparini M., Landolina M. et al. Device-detected atrial tachyarrhythmias predict adverse outcome in real-world patients with implantable biventricular defibrillators. J Am Coll Cardiol. 2011;57:167–172.
8. Varma N., Stambler B., Chun S. Detection of atrial fibrillation by implanted devices with wireless data transmission capability. Pacing Clin Electrophysiol. 2005;28(Suppl 1):S133–S136.
9. Varma N., Epstein A, Irimpen A. et al. TRUST Investigators. Efficacy and safety of automatic remote monitoring for ICD follow-up: the TRUST trial. Circulation. 2010;122:325–332.
