1. Implantable Monitoring Systems Vs Wearables: When & How
Suneet Mittal, MD
Director, Electrophysiology
Director, The Snyder Center for Comprehensive Atrial Fibrillation
Director, Cardiac Research
February 21, 2019
Disclosures: Consultant to Abbott, Boston Scientific, and Medtronic
WESTERN AF 2019 PROGRAM
@drsuneet
 CARDIAC RESYNCHRONIZATION THERAPY 2017: 
BUILDING A PROGRAM TO GET ALL PATIENTS SUCCESSFULLY TO THE FINISH LINE 

2. Lifecycle of AF Patients
Diagnosis and Monitoring
Stroke
Prevention
Treatment
Drugs
Devices
Ablation
Risk Factor
Modification

3. 4.6 Million Tests Annually
ECG Monitoring Tools
ILR
~100,000
MCT Monitors
~400,000
4.6 Million Tests Annually
1.4 Billion USD
Holter Monitor
~2.8 Million
Event Monitor
~1.3 Million

4. ECG Monitoring Tools Lead Based (1-Piece) Smartphone Event Recorder
Scottcare– TeleSense, TeleSentry
Spectacor – Pocket ECG
TeleRhythmics – Heartrak TCAT
Smartphone
(e.g., Alivecor)
Event
Recorder
Spot Single-Lead ECG
Check
Smartwatch
(e.g., Kardiaband)
Holter
Holter Monitoring
(1-2 days)
Holter Monitoring
(1-2 weeks)
Lead
Based
(e.g., CardioKey)
(e.g., Zio)
(e.g., ePatch)
Patch Based
Lead Based (2-Piece)
Applied Cardiac Systems – CORE
Biomedsys – TruVue
Infobionic – MoMe Kardia
Lifewatch – ACT Elite
Medicomp – Duet
Mobile Telemetry Monitoring
(Up to 30 days)
Lead
Based
(e.g., multiple; Telesense)
(e.g., SEEQ,
Body Guardian)
Patch Based
Garment
Based
(e.g., nECG)
Patch Based
Biotelemetry – MCOT Patch
Lifewatch – ECG mini
Medicomp – TelePatch
Medtronic – SEEQ
Nuubo - nECG
Preventice – Body Guardian
Implantable Loop Recorder
(Up to 3 years)
Mittal S et al. JACC 2011; 58: ; Mittal S. CIR 2017; 25: 12-16; Lee RJ, Mittal S. Heart Rhythm 2018

5. Case Presentation
50-year old female with hypertension and Sjogren's syndrome reports a several year complaint of palpitations associated with light-headedness.
Episodes occur every few weeks and last 5-10 minutes.
There has been no ECG documentation obtained during her typical episode.
Her baseline ECG and echocardiogram are entirely normal.
She presents for further evaluation
CHA2DS2-VASc =2 (if she had atrial fibrillation).

6. Smartphone Based Diagnosis
Cheap
Owned by the patient
Real time
Long term
High fidelity recordings
No intermediary between patient and doctor

8. Smartphone ECG Monitoring: Potential Applications
Diagnose etiology of unexplained palpitations
In patients with known paroxysmal atrial fibrillation,
Assess heart rate in sinus rhythm vs. atrial fibrillation
Assess relationship between symptoms and recurrence of atrial fibrillation in patients being treated with anti-arrhythmic drugs and/or catheter ablation
In patients with persistent atrial fibrillation,
Daily objective self monitoring for exclusion of arrhythmia recurrence

9. Case Presentation
74-year-old male with hypertension and remote history of SVT ablation.
A year and a half ago, he had a stress echocardiogram. He exercised for 6 ½ minutes on a Bruce protocol. The exam was normal.
He recently noticed that his heart rate was elevated while at the gym. He had no symptoms referable to a rate.
An ECG demonstrated atrial fibrillation with rapid ventricular response. An echocardiogram demonstrated a left atrial diameter of 3.7 cm, left atrial volume index of 31.2 mL/m², a 4.4 cm aortic root, and an ejection fraction of 30%.
He was referred for evaluation; an ECG showed sinus rhythm. (CHA2DS2-VASc = 2)

10. Case Presentation

11. Duration vs. Burden
JAMA Cardiology 2018

12. Duration vs. Burden
JAMA Cardiology 2018

13. mSToPS Trial
Steinhubl SR et al.
JAMA 2018;
320:

14. Smartwatches for AF Detection
Bumgarner JM et al.
JACC 2018
71 (21):

15. Smartwatch Photoplethysmography Coupled with a Deep Neural Network
Tison GH et al JAMA Cardiology 2018; 3 (5):

16. Smartwatches for AF Detection

17. How Well Do These Devices Perform? Implantable Loop Recorder
Longest
≥2 min
≥6 min
≥10 min
≥30 min
≥1 hour
Episode PPV (%)
PPV excellent for AF episodes > 1 hour, irrespective of population being evaluated
Imperfect assessment of AF burden: atrial and ventricular ectopy; atrial tachycardia
Mittal S. et al.
Heart Rhythm 2016;
13: 1624–1630 

18. ILR Guided Anticoagulation Post-AF Ablation
REACT.COM
n=59
94% reduction in the time on NOAC compared to chronic anticoagulation
No strokes or deaths
Passman R et al.
JCE 2016

19. Which AECG Monitor for Which Patient?
Indication for Monitoring
Rationale
Strength
Limitations
Caveats /
Potential Alternatives
Suspected AF
(e.g., cryptogenic stroke)
30% AHRE detection
over 3-years
Higher AHRE detection than conventional follow-up
PPV for AHREs < 1 hour is sub-optimal
Clinical significance of AHREs < 24 hours is uncertain
If only AHREs > 24 hours are clinically significant, daily ECG monitoring with a smartphone sufficient.

20. Which AECG Monitor for Which Patient?
Indication for Monitoring
Rationale
Strength
Limitations
Caveats /
Potential Alternatives
Known AF
Establish AF pattern
Differentiating pattern of AF is important when choosing medical and ablation options
Continuous ECG monitoring can perfectly distinguish patterns of AF
Impractical to implant a device for this sole purpose
Daily ECG monitoring with a smartphone sufficient to exclude persistent AF
Assess efficacy
To compare the effectiveness of different AF management strategies, important to know with uncertainty whether AF has or has not been eliminated
Continuous ECG monitoring is the best available tool to capture information about all recurrences of AF; information about AF duration and burden is available
High NPV but only modest PPV
AF burden can be overestimated (false positive classification due to sinus arrhythmia, atrial and ventricular ectopy)
None; in foreseeable future, ILRs will remain the best available technology for this purpose. Ideally suited to measure efficacy in ongoing clinical trials

21. Which AECG Monitor for Which Patient?
Indication for Monitoring
Rationale
Strength
Limitations
Caveats /
Potential Alternatives
Guide management
“Pill-in-the-pocket” anticoagulation
Following a successful ablation procedure, many patients ask to discontinue anticoagulation, irrespective of their CHA2DS2-VASc score.
Three pilot studies have shown anticoagulation can be withheld following ablation if there are no AHREs > 1 hour
The PPV for AHREs < 1 hour is sub-optimal.
Current technology not robust enough to ensure 100% connectivity
Establishing infrastructure to respond to all recurrences of AF in patients is difficult
Wearables – incorporation of an ECG monitor within a wearable (watch) may alert the patient about significant recurrences of AF

22. Implantables vs. Wearables
General Population
High Risk
Asymptomatic
Symptomatic
Initial Diagnosis
Ongoing
Management
10 Million
4.5 Million
Abnormal ECG
Palpitations
1 Million
Post-Ischemic Stroke
AF Management
Adapted from iRhythm
Investors Call Jan 2019