History
This 54-year-old man first sought treatment in 2005 with symptoms of progressive dyspnea on exertion, pedal edema accompanied by paroxysmal nocturnal dyspnea, and orthopnea. He had initially been treated in the community for upper respiratory tract infection with oral antibiotics but then developed symptoms of shortness of breath and fatigue. On further medical testing, he was diagnosed with dilated cardiomyopathy. His initial echocardiogram showed dilated cardiomyopathy with left ventricular internal diameter at end-diastole of 64 mm Hg, left ventricular ejection fraction (LVEF) of 18% with diffuse hypokinesis, moderate mitral regurgitation, left atrial enlargement, and moderate-to-severe tricuspid regurgitation.
The patient’s risk factors included active cigarette smoking, with a 25 pack-year history, and hyperlipidemia. He underwent cardiac catheterization, which showed mild obstructive coronary artery disease; however, this was unlikely to explain the severity of his cardiomyopathy and symptoms.
A single-lead implantable cardioverter-defibrillator (ICD) was originally placed in March 2010 for New York Heart Association (NYHA) class II symptoms with a QRS duration of 110 ms. Progressive worsening and widening of his QRS duration resulted in an upgrade to a cardiac resynchronization therapy defibrillator (CRT-D) with the addition of atrial and left ventricular leads. His NYHA classification had worsened to NYHA class III with hospitalizations for heart failure. Because of his relatively narrow QRS duration (126 ms), he also underwent a dyssynchrony echocardiographic study to ascertain the potential value of an upgrade of his ICD.
After the upgrade he came to our clinic for an unscheduled visit after being “bothered” by an audible tone from his device occurring every morning over several consecutive days. He described it as “an annoying occurrence” during his morning business meetings. His device interrogation was notable for inappropriate ICD therapy having occurred while he was asleep 7 days previously. The intracardiac electrograms documented atrial fibrillation with rapid ventricular response, which converted to sinus rhythm after he received one 34-J shock. After this initial shock he connected and established himself on our remote monitoring system.
He proceeded over the next several months to have several episodes of paroxysmal atrial fibrillation, which were detected accurately by his remote monitoring intracardiac electrograms, as exemplified in Table 48-1. Amiodarone therapy was started, but poorly tolerated secondary to neurologic effects of increased somnolence and fatigue, which led to the patient discontinuing the medication. On the amiodarone, his activity level decreased significantly, as seen on remote monitoring, although his biventricular pacing quantities went up significantly, as highlighted and circled in Figure 48-1.
The choices for alert alarms are audible and/or system monitor alerts that can range from 3 to 24 hours, including settings for the accompanying ventricular rates. For patients with heart failure, it is beneficial to set these parameters conservatively because the onset of atrial fibrillation could exacerbate their heart failure.
As a result of increasing heart failure symptoms, a month-long trial of turning off the left ventricular lead was done, but his heart failure symptoms worsened over the following weeks. As indicated earlier, his baseline QRS duration was fairly narrow, at 126 ms, which can be a substrate for nonresponse to CRT.
FIGURE 48-1 Decreased quantities of biventricular pacing present along with activity level trends. AF, Atrial fibrillation; AT, atrial tachycardia; V, ventricular.
TABLE 48-1
Remote Arrhythmia Episode List
| Type | ATP Seq | Shocks | Success | ID no. | Date | Time hh:mm | Duration hh:mm:ss |
Average BPM A/V |
| AT/AF | 102 | 17-Sep-2012 | 04:32 | (Episode in progress) | ||||
| AT/AF | 101 | 17-Sep-2012 | 03:48 | :44:22 | 178/98 | |||
| AT/AF | 100 | 17-Sep-2012 | 00:16 | 03:31:53 | 180/90 | |||
| AT/AF | 99 | 16-Sep-2012 | 02:17 | 21:58:27 | 180/91 | |||
| AT/AF | 98 | 15-Sep-2012 | 23:20 | 02:57:42 | 178/89 | |||
| AT/AF | 97 | 15-Sep-2012 | 01:10 | 22:09:17 | 180/90 | |||
| AT/AF | 96 | 15-Sep-2012 | 00:06 | 01:04:13 | 175/87 | |||
| AT/AF | 95 | 14-Sep-2012 | 14:10 | 09:56:19 | 178/88 | |||
| AT/AF | 94 | 14-Sep-2012 | 13:59 | :10:43 | 176/88 | |||
| AT/AF | 93 | 14-Sep-2012 | 08:20 | 05:38:34 | 176/88 | |||
| AT/AF | 92 | 14-Sep-2012 | 05:22 | 02:57:52 | 176/86 | |||
| AT/AF | 91 | 13-Sep-2012 | 19:38 | 09:44:24 | 169/83 | |||
AF, Atrial fibrillation; AT, atrial tachycardia; ATP Seq, anti-tachycardial pacing sequence; A/V, atrioventricular; BPM, beats per minute; hh, hours; ID, identification; mm, minutes; ss; seconds.
As his heart failure progressed, he developed multiple episodes of nonsustained ventricular tachycardia, some of which occurred at ventricular rates as low as 131 bpm. These ventricular arrhythmias were preceded by elevations in his intrathoracic lead impedance fluid index trends measured in Ohms and identified as OptiVol in Medtronic (Medtronic, Minneapolis, Minn.) devices. His impedance measurements became important to monitor on a regular basis, because they were an accurate predictor of his heart failure exacerbations. Remote monitoring trends of these episodes are viewed in Figure 48-2.
The patient’s clinical trajectory went further downhill as he developed persistent atrial fibrillation, with rapid ventricular rates and decreased percentages of biventricular pacing ultimately requiring cardioversion. Because of the size of his left atrium, the occurrence of atrial fibrillation was not unexpected. He had not been on anticoagulation therapy and was started on dabigatran when his lifestyle proved that he would not be compliant for frequent blood level international normalized ratio blood sample checks on warfarin.
Current Medications
The patient was taking captopril 6.25 mg three times daily, carvedilol 6.25 mg twice daily, furosemide 40 mg twice daily, spironolactone 25 mg daily, digoxin 0.125 mg daily, atorvastatin 80 mg daily, and aspirin 81 mg daily. Carvedilol was discontinued when his blood pressure was no longer high enough, and metoprolol was resumed. His diuretic medications included torsemide 80 mg twice daily, with an additional 80 mg as needed based on daily weight. Metolazone 2.5 mg was then added on an as-needed basis. His intolerance of amiodarone and ongoing ventricular arrhythmias necessitated the initiation of low-dose sotalol, which was eventually titrated up to 120 mg twice daily for treatment of ventricular arrhythmias as documented by his remote transmission (Figure 48-3) that required ICD therapies.
FIGURE 48-2 Intrathoracic impedance trends.
Comments
The remote monitoring of cardiac implantable devices is rapidly growing throughout most of our clinical practices. Remote transmissions are being used to replace in-office device checks and provide a method of surveillance for recalled leads. For patients with CRT devices, programmed device alerts are frequently indicative of a clinical change requiring intervention. Previous work reported that 86% of remote monitoring events done on daily transmissions were due to medical conditions, including detection of supraventricular or ventricular arrhythmias, ICD therapy, or paroxysmal atrial fibrillation, as opposed to lead or technical problems.5 Early detection of these electrophysiologic issues or clinical trends can result in earlier intervention and decreased mortality. In this case study, close monitoring of the patient alerts through the remote system prevented several potential admissions and ICD therapies because his medications were adjusted while he remained at home. In this single case study the audible alert actually prompted the patient’s first clinic visit. He sought health care only because of the bothersome audible tone coming from his device. This may serve as a useful feature to keep programmed on in patients with issues of compliance. The Diagnostic Outcome Trial in Heart Failure (DOT-HF) study demonstrated that audible alerts may increase hospital admissions. This is because OptiVol measures as a predictor of heart failure exacerbations lack specificity and may result in patients and physicians overreacting to a false-positive alert.
FIGURE 48-3 Ventricular tachycardia with a 35-J shock.
Physical Examination
Laboratory Data
Electrocardiogram
The electrocardiogram showed sinus rhythm at 67 bpm, first-degree atrioventricular block with a PR interval of 228 ms, QRS duration 126 ms, left axis deviation consistent with a left anterior fascicular hemiblock, poor R-wave progression across the precordium, and Q-waves in the inferior leads.
Chest Radiograph
On chest radiography the cardiomyopathy was shown to be stable. Both lungs were inflated and clear (Figure 48-4).
Exercise Testing
In the myocardial imaging (Regadenoson) stress test, the patient’s heart rate reached 37% of predicted rate, achieving the metabolic equivalent of task of 1. No evidence of ischemia was found, and the LVEF was 33%. Moderate right and left ventricular dilation were present.
Dyssynchrony Echocardiogram
The dyssynchrony echocardiogram revealed a left atrial pressure of 53 mm, left ventricular internal diameter at end-diastole of 63 mm, left ventricular internal diameter at end-systole of 54 mm, right ventricular systolic pressure of 35, and LVEF of 26%. For interventricular mechanical delay, the difference between left ventricular and right ventricular preejection intervals, the patient’s value was −37 ms. The left ventricular preejection interval was 174 ms. The left ventricular filling ratio, the ratio of left ventricular filling time to cardiac cycle length, was 29%. The opposing wall delay between the peak longitudinal systolic velocities in the basal septal and lateral walls was 185 ms, the maximum difference in time to peak longitudinal systole was 202 ms, and the standard deviation in time to peak longitudinal systolic velocity among 10 left ventricular segments (midanterior and posterior segments were excluded) was 76 ms. Mechanical dyssynchrony was present, with the lateral segments demonstrating the most delayed systolic motion.
Cardiac Catheterization
The patient’s cardiac output is 3.68 L/min, cardiac index is 1.8 L/min/m2, peripheral vascular resistance was 109 dyn∗s/cm5, and systemic vascular resistance was 1475, with a ratio of 0.075. The right atrium was 30/20 (v/m), right ventricle was 40/9 s/edp, wedge was 37/32, pulmonary artery was 45/32/37, and left ventricle was 97/37. His left main coronary artery was normal; 40% focal stenosis was found in the proximal third of the mid–left anterior descending artery. The left circumflex and right coronary arteries were normal. Combined systolic and diastolic heart failure also was present.
FIGURE 48-4 Chest radiographs. A, Posterior anterior view. B, Lateral view.
Pulmonary Function Testing
The patient’s forced expiratory volume in 1 second measured 2.94 L/second, which is 75% of predicted value. His forced vital capacity measured 4.13 L, which was 83% of predicted value, with forced expiratory flow measuring 2.94 L/second, or 52% of predicted capacity. The findings demonstrated a mild obstructive ventilatory defect.
Outcome
As the patient’s heart failure and arrhythmias worsened, his remote alerts became more frequent and the management of his care on an outpatient basis was facilitated by these alerts. He went into atrial flutter with ventricular sensed response pacing. Examination of his remote internal electrograms demonstrated the presence of ventricular trigger pacing (Figure 48-5).
Final Diagnosis
This patient had dilated cardiomyopathy, with both paroxysmal atrial fibrillation and ventricular arrhythmias.
Comments
Remote monitoring of this patient’s device led to multiple interventions, some of which prevented hospitalizations and led to earlier detection of both atrial and ventricular arrhythmias. The importance of examining and monitoring the quantity of biventricular pacing and differentiating the degree of trigger or ventricular assisted pacing is essential in this fragile population. At time of publication, biventricular pacing alerts are not available on all device platforms, but support for their value has been demonstrated.3,4 Ultimately, with the assistance of these last remote alerts, it was determined that the patient was nearing the end of life. He had declined the option of heart transplantation. The decision was made to not proceed with synchronized electrical cardioversion for his last episode of atrial flutter and to turn off his defibrillator. The focus then became quality at the end of life; he was then admitted to hospice, where he died within 48 hours.
Figure 48-5 Atrial flutter with ventricular sensed response pacing and loss of true biventricular pacing. EGM, Electrogram; LV, left ventricle; RV, right ventricle; SVC, superior vena cava; VS, ventricular sensing.
Focused Clinical Questions and Discussion Points
Question
Does the usage of remote monitoring decrease health care usage?
Discussion
Although the mortality and hospitalization benefits of remote monitoring have been demonstrated,5,7 it appears that other potential cost savings have not consistently been supported, possibly because of nonstandardization of monitoring protocols, procedures, and equipment. A significant amount of variability exists among alert settings, which can lead to increased health care costs. In the intrathoracic impedance monitoring study DOT-HF,9 which examined whether heart failure patient management using measurements of intrathoracic impedances with an implanted device as a means of detecting increases in pulmonary fluid would lead to a reduction in the combined end point of all-cause mortality or heart failure hospitalizations, results included an increase in heart failure admissions and outpatient visits because of patients receiving audible alerts for daily fluctuations in impedance that were not clinically significant.
Audible patient tone alerts can create increased anxiety for patients and cannot be cleared without a visit to a device clinic or emergency room. This can be burdensome to patients who do not have easy access to a device clinic or especially if these alerts occur during nonclinic hours. At this juncture the use of these alerts should be individualized, based on the patient’s clinical condition and some prior information on the correlation of these alerts with cardiac decompensation.
Having an audible alert was very important for this patient, who had not set up his remote system. Clearly if the audible alert had not gone off, he would not have gone to the clinic. On some devices, certain alerts can be evaluated and then cleared remotely. This alleviates undue anxiety for both patients and their household members or associates. In addition, with newer device implants, unfamiliarity and lack of education about these vibratory tones can be confused with antitachycardia pacing therapy or diaphragmatic stimulation.
Question
Does remote monitoring decrease mortality?
Discussion
The work done in the Altitude Survival Study that followed patients on the Boston Scientific Corporation (Natick, Mass.) remote monitoring system LATITUDE demonstrated a 50% relative reduction in the risk for death in contrast to that of patients followed in-clinic only.7 Patients who transmitted weight and blood pressure data via the LATITUDE system experienced an additional 10% reduction in the risk for death in contrast to other networked CRT-D patients followed on LATITUDE. Patients who transmitted regular weight and blood pressure data in addition to their ICD parameters experienced an additional 10% mortality reduction in contrast to others who had only ICD parameters monitored on LATITUDE.
Question
Should we standardize remote alert settings according to diagnosis or device clinic practices?
Discussion
A great deal of variation remains among clinical practices regarding the manner in which remote monitoring is used. In a study of remote alerts, the remote alert settings appeared to be a crucial parameter in the efficacy of remote monitoring. This study found that more attention was paid to critical technical data such as battery exhaustion, impedances, sensing, and threshold measurements than to patients’ clinical profiles, including heart rate monitoring and supraventricular arrhythmias.2
In addition, the time intervals between device checks and the level of personnel monitoring the transmission of this information have no clear standardization. Some practices continuously use it, in addition to routine scheduled device follow-up, and actively evaluate clinical parameters between visits. The actual practice standard of usage was 62% of CRT-D in patients managed by physicians with remote monitoring in addition to routine office follow-up.7 No homogeneous standard of practice exists for evaluations, with times ranging from 3 months to only once annually.6 Other clinical parameters that can be used to monitor heart failure include heart rate variability, lower daily activity, weights, and abnormal heart rates, all of which provide ongoing trends between scheduled visits. These parameters will not be used to their fullest capacity until consensus can be reached regarding convenience and efficient usage for clinicians.1 Preventing heart failure hospitalization necessitates thinking about remote monitoring differently and understanding that parameters that may help predict heart failure exacerbation must be monitored more carefully. Some of the parameters shown to be predictive of increased mortality include mean heart rate, heart rate variability, and physical activity.8 The Program to Access and Review Trending Information and Evaluate Correlation to Symptoms in Patients With Heart Failure (PARTNERS HF) study evaluated variables to predict heart failure. Patients were observed to have a higher hospitalization rate if they had two of the following abnormal criteria during a 1-month period: long atrial fibrillation duration, rapid ventricular rate during atrial fibrillation, high (≥60) fluid index, low patient activity, abnormal autonomics (high night heart rate or low heart rate variability), or notable device therapy (low CRT pacing or ICD shocks) or if they only had a very high (≥100) fluid index.10
An international variability also remains in the usage of remote monitoring, which is affected by variables outside of clinician control such as the type of telecommunications equipment in patient homes, reimbursement for remote follow-up visits, and geographic distance between clinics and patient homes. The legal ramifications for identification and intervention of remote alerts in clinical settings with varied resources on a timely basis also need to be clarified.
Question
Is the percentage of biventricular pacing present an important parameter to monitor remotely?
Discussion
The percentage of biventricular pacing that matters, as discussed earlier, is not a parameter standardized as an alert on all CRT device remote alert systems. In a cohort study of 36,935 patients followed on the LATITUDE management system, mortality was inversely associated with the percentage of biventricular pacing both in the presence of sinus rhythm and when atrial pacing or atrial fibrillation was present. The greatest magnitude of reduction of mortality was observed with a biventricular pacing cutoff in excess of 98%.3
Selected References
1. Daubert J.C., Saxon L., Adamson P.B. et al. 2012 EHRA/HRS expert consensus statement on cardiac resynchronization therapy in heart failure: implant and follow-up recommendations and management. Heart Rhythm. 2012;9:1524–1576.
2. Folino A.F., Chiusso F., Zanotto G. et al. Management of alert messages in the remote monitoring of implantable cardioverter defibrillators and pacemakers: an Italian single-region study. Europace. 2011;13:1281–1291.
3. Hayes D.L., Boehmer J.P., Day J.D. et al. Cardiac resynchronization therapy and the relationship of percent biventricular pacing to symptoms and survival. Heart Rhythm. 2011;8:1469–1475.
4. 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.
5. Lazarus A. Remote, wireless, ambulatory monitoring of implantable pacemakers, cardioverter defibrillators, and cardiac resynchronization therapy systems: analysis of a worldwide database. Pacing Clin Electrophysiol. 2007;30(Suppl 1):S2–S12.
6. Marinskis G., van Erven L., Bongiorni M.G. et al. Practices of cardiac implantable electronic device follow-up: results of the European Heart Rhythm Association survey. Europace. 2012;14:423–425.
7. Saxon L.A., Hayes D.L., Gilliam F.R. et al. Long-term outcome after ICD and CRT implantation and influence of remote device follow-up: the ALTITUDE survival study. Circulation. 2010;122:2359–2367.
8. Singh J.P., Rosenthal L.S., Hranitzky P.M. et al. Device diagnostics and long-term clinical outcome in patients receiving cardiac resynchronization therapy. Europace. 2009;11:1647–1653.
9. van Veldhuisen D.J., Braunschweig F., Conraads V. et al. Intrathoracic impedance monitoring, audible patient alerts, and outcome in patients with heart failure. Circulation. 2011;124:1719–1726.
10. Whellan D.J., Ousdigian K.T., Al-Khatib S.M. et al. Combined heart failure device diagnostics identify patients at higher risk of subsequent heart failure hospitalizations: results from PARTNERS HF (Program to Access and Review Trending Information and Evaluate Correlation to Symptoms in Patients With Heart Failure) study. J Am Coll Cardiol. 2010;55:1803–1810.
