Device therapy –Diagnostic and Therapeutic

Marilyn M. Cox M.D., F.A.C.C.

Overview of Device Therapy

Implantable loop recorders

Pacemakers

Implantable Cardioverter-Defibrillators- Single, Dual, Biventricular and Sub Q

Future devices

Extended EKG monitoring

Choice of monitoring should depend upon the frequency of the patient's symptoms

Daily symptoms-24 hour holter

Weekly symptoms-30 day event recorders

Monthly or less – Implantable loop recorders

External recording systems

Cardionet-30 day wireless, non-looping, looping and auto-trigger monitors, detects and automatically transmits asymptomatic and symptomatic events.

Lifewatch-sensor and electrodes are worn on chest , wireless transmission of heart beat to cellular phone monitor where it is analyzed. If arrhythmia is detected cell phone automatically sends it monitoring center

SEEQ- 30 day monitor, continuous wireless data collection and transmission, sensor patch adheres to skin, 7 day sensor

Preventice eCardio-detects, records and wirelessly transmits data to support remote monitoring. Sensor adheres to patient’s skin and is smaller than cell phone

Looping multi-event monitors

Looping refers to memory of the monitor, when activated monitor can save the previous 60 seconds of data and 30 seconds post activation

Patient activated

Program to record 1-6 events

Advantage of implantable loop recorders

Small

No external EKG patches or wires

No need to rely on patient to record

Reveal XT versus Reveal Linq

REVEAL LINQ Insertable Cardiac Monitoring System

Miniaturized cardiac monitoring for up to 3 years

Continuous , wireless data collection, trending and transmission

24/7 physician access to reports with automatic notification for clinically relevant events

Reveal Linq Implantable Cardiac Monitor

20% more data memory than previous models

Improved AF detection

Three year longevity

MRI conditional at 1.5 and 3.0 Tesla

Comes preloaded in insertion tool

Requires only local anesthesia

Implantable loop recorder kit

Insertional tool loaded with implantable loop recorder

Objectives of CRYSTAL AF

To assess whether a long term monitoring strategy with an insertable cardiac monitor (ICM) is superior to standard medical care for the detection of AF in patients with cryptogenic stroke at 6 months( primary endpoint) and 12 months( secondary endpoint)

Determine the proportion of patient with cryptogenic stroke that have underlying AF

Determine actions taken after patient is diagnosed with AF

Crystal AF trial

Crystal AF

Secondary Endpoint: Detection of AF at 12 monthsICM finds 7x more patients with AF

Rate of detection in ICM arm was 12.4% vs 2.0% in control arm

Crystal AF trial

Indications for pacing

Documented non-reversible symptomatic bradycardia due to sinus node dysfunction Documented non-reversible symptomatic bradycardia due to second degree and/or third degree heart block

Symptoms of bradycardia directly attributable to a heart rate less than 60 BPM

Syncope

Seizures

Congestive heart failure

Dizziness

Confusion

Pacing not indicated-according to CMS

Reversible causes of bradycardia such as electrolyte abnormalities, medication or drugs and hypothermia

Asymptomatic first degree AV block

Asymptomatic sinus bradycardia

Asymptomatic sino-atrial block or asymptomatic sinus arrest

Asymptomatic Mobitz type I AV block (Wenckebach) unless QRS complexes are prolonged or EPS shows block is at or below the His bundle

Syncope of undetermined cause

Bradycardia during sleep

Asymptomatic bradycardia

Pacing not indicated according to CMS

Asymptomatic bradycardia in post MI patients about to initiate long term beta blocker therapy

Right bundle branch block and left hemiblock without syncope or symptoms of intermittent AV block

Frequent or persistent SVT except where pacemaker is for control of tachycardia

A clinical condition in which pacing takes place only intermittently and briefly and which is not associated with reasonable likelihood that pacing will not become prolonged

What information does a pacemaker interrogation give us?

Battery life, serial numbers

Implant data, patient characteristics, indication

Lead characteristics( P and R wave amplitude, impedance, pacing threshold)

Heart rate histograms

Mode switch episodes ( number and percentage of total time)

Arrhythmia recordings- SVT, A fib, VT, VF

Intracardiac electrograms of the arrhythmias

Rate, number of episodes, date and time of episodes, duration of individual episode

MRI Conditional Pacemakers

Why is an MRI conditional pacemaker important?

MRI is predominantly used to diagnose back and joint pain, stroke symptoms and cancer

Also used to examine the abdomen, pelvis, breast , blood vessels and heart

49% of patients with a stroke or TIA undergo an MRI within 3 days of symptoms but patients with traditional pacemakers cannot

86% of pacemaker patients are older than 65 and prevalence of common morbidities increase over age 65

MRI is the standard or care for these multiple morbidities

Cardiology conditions for use of an MRI

No lead extenders, lead adaptors or abandoned leads

No broken leads or leads with intermittent electrical contact as confirmed by lead impedance history

System has been implanted for at least 6 weeks

System has been implanted in the right or left pectoral area

Pace polarity parameters set to Bipolar for programming MRI sure scan to on

Pacing capture thresholds of less than or equal to 2 V at 0.4 ms,

Lead impedance of >200 ohms and < 1500 ohms

No diaphragmatic stimulation at 5V and pulse width of 1ms in patients whose device will be programmed to an asynchronous mode

Source: Medtronic

Radiology conditions for use of an MRI

Full body MRI is now allowed, no restrictions

Horizontal cylindrical bore magnet, clinical MRI systems with a static magnetic field of 1.5 Tesla must be used

Gradient systems with max slew rate performance per axis of < or = to 200 Tesla/m/sec must be used

Scanner must be in normal operating mode: whole body average specific absorption rate (SAR) < or = to 2 W/kg; head SAR must be <or = 3.2W/kg

Proper patient monitoring must be provided including visual and verbal contact with patient and heart rate monitoring with pulse ox or EKG

An external defibrillator must be available nearby during the MRI scan

Source: Medtronic

MRI precautions

Do not scan patients with a whole body average SAR of >2W/kg as this may increase the risk of myocardial tissue damage due to lead tip heating

Do not scan patients with capture thresholds >2 V at 0.4 ms as this indicate that there is a problem with the implanted lead

Do not scan patients whose device will be programmed to an asynchronous mode who have diaphragmatic stimulation at 5V at 1 ms as it may be difficult for patient to remain still in order to obtain a quality image

Use of lead extenders or lead adaptors is not recommended as they may increase the risk of myocardial tissue damage due to lead tip heating and other MRI field related hazards

Scanning patients with multiple MR conditional devices is acceptable as long as the MR labeling conditions for all implants can be satisfied

Indications for Implantable Cardioverter Defibrillators

Primary prevention

Secondary prevention

ICDs for the Secondary Prevention of Sudden Cardiac Death

Survivors of cardiac arrest due to VF or hemodynamically unstable VT

Completely reversible causes of VF or VT are not covered

ICDs for the Primary Prevention of Sudden Cardiac Death

Patients with ischemic dilated CM , documented prior MI, NYHA functional Class II and III and LV EF less than or equal to 35%

Patients with non-ischemic dilated CM greater than 3 months, NYHA functional class II and III and LV EF less than or equal to 35%

LV dysfunction due to prior MI and at least 40 days post MI, EF less than 30% and NYHA functional Class I

Hypertrophic cardiomyopathy and risk of SCD

Long QT syndrome and risk of SCD

Brugada syndrome and risk of SCD

Disqualifiers for ICD implantation for Primary prevention

Patient unable to give informed consent

Cardiogenic shock or symptomatic hypotension while in a stable baseline rhythm

CABG or PCI within the past 3 months

Acute MI within the last 40 days

Clinical symptoms that would make patient a candidate for revascularization

Irreversible brain damage from preexisting cerebral disease

Any disease other than cardiac disease (e.g. cancer, uremia, liver failure associated with a survival of less than one year

Goal of Cardiac Resynchronization therapy

Reestablish synchronous contraction between the left ventricular free wall and the ventricular septum in an attempt to improve left ventricular efficiency and subsequently to improve functional class

Benefits of Cardiac Resynchronization therapy

Improve pump performance

Reduce functional mitral regurgitation

Reverse adverse effects of ventricular remodeling in patients with heart failure

Reduce mortality

Reduce heart failure symptoms

Reduce heart failure hospitalizations

Schematic of Biventricular ICD

Coronary sinus venogram

Biventricular ICD

MADIT CRT-

Designed to determine whether cardiac resynchronization therapy (CRT) with biventricular pacing would reduce the risk of death or heart failure in patients with mild symptoms, a reduced EF and a wide QRS complex

1820 patients with ischemic or non-ischemic CM, EF of 30% or less, QRS 130ms or more, NYHA functional Class I or II symptoms

Patients randomly assigned in 3:2 ratio to receive CRT plus ICD or CRT alone

Primary endpoint death from any cause or nonfatal heart failure event(whichever came first)

MADIT CRT Results

Average follow up of 2.4 years

Primary endpoint occurred in 187 of 1089 CRT-ICD patients(17.2%) and 185 of 731 patients in the ICD-only group (25.3%) (p=0.001)

Benefit did not differ significantly between ischemic and non-ischemic CM

Superiority of CRT driven by a 41% reduction in risk of HF events ( evident in subgroup of patients with QRS of 150 msec or more

CRT associated with a significant reduction in LV volumes and improvement in EF

No significant difference in between 2 groups in overall risk of death-3 % annual mortality in both groups

ICD Programming

Pacing therapy for tachy and bradyarrhythmias

Cardioversion therapy

Defibrillation therapy

Multicenter Automatic Defibrillator Implantation Trial Reduce Inappropriate Therapy – MADIT-RIT- Background

ICD is highly effective in reducing mortality in high risk cardiac patients

Despite sophisticated device detection algorithms, 8-40% of ICD therapies are inappropriate with adverse side effects

Question: can ICDs be reprogrammed to reduce inappropriate therapies?

NEJM 2012;367:2275-2283

MADIT RIT Hypothesis

Dual chamber ICD or CRT-D devices with a high rate cut-rate cut of (200 BPM), or a duration delay( initial 60 sec monitoring delay) will be associated with fewer first inappropriate therapies than standard conventional programming (2.5.sec delay@>170 BPM) without an increase in mortality

Randomized 3 arm study of patients randomized 1:1:1 to either conventional, high-rate cutoff, or duration delay programming

Primary endpoint : first episode of inappropriate therapy ( defined as shock or ATP)

Secondary endpoints: All cause mortality , Syncope

NEJM 2012;367:2275-2283

MADIT RIT-Three treatment arms Conventional therapy

Conventional therapy: 2 detection zones

First detection zone : 170-199 BPM with a 2.5 second delay and atrial discriminators turned on

Second detection zone: 200 BPM with a one second delay before delivery of anti-tachycardia pacing or shock

MADIT RIT: High rate group

Monitor only zone between 170 and 199 BPM

Therapy zone beginning at 200 BPM after a 2.5 second delay

MADIT RIT: Delayed therapy group

3 detection rates

First zone –detection rate 170-199 BPM with rhythm detection on and a 60 second delay before initiation of therapy

Second zone-detection rate of 200 BPM with rhythm detection on and a 12 second delay before therapy

Third zone-detection rate of 250 BPM or higher with a 2.5 second delay before initiation of therapy

In all zones anti-tachycardia pacing was followed by shock therapy if pacing did not terminate the detected tachyarrhythmia

NEJM 2012:367;2275-2283

MADIT RIT –Probability of first occurrence of inappropriate therapy according to treatment group

MADIT RIT Summary

Improved ICD programming to high rate (>200 BPM) or 60 second duration delay is associated with :

~75% reduction in first inappropriate therapy

~50% reduction in all-cause mortality when compared to conventional programming

Source :NEJM 2012;367:2275-2283

Remote monitoring of devices-why should we do it?

To identify clinically important issues such as device integrity issues, programming issues and asymptomatic arrhythmia detection

Advantages of remote monitoring

Earlier detection of supraventricular and ventricular arrhythmias

Earlier detection of atrial fibrillation

Earlier detection of CHF

Earlier detection of lead problems

Follow up of leads on advisory list

Device clinic

Device clinic

Device clinic team

Subcutaneous ICDs

Generator is connected to a subcutaneous electrode

ICD electrode is subcutaneously implanted from device pocket along rib margin to the sternum

Advantages of the Sub Q ICD

Absence of leads inside the heart and the preservation of central venous circulation make it a great alternative for children with congenital heart disease or patients with no venous access who were unsuitable for transvenous ICD

No risk of vascular injury or pneumothorax

Risk of systemic infections appears very low, best in high risk cases of previous device infection, hemodialysis, chronic immunosuppressive therapy, immunodeficiencies or artificial heart valves

Although pocket infections can occur(5-10%, similar to transvenous devices)infection resolves with antibiotics in the majority of cases

Explantation is rarely necessary, however explantation is much simpler and safer than transvenous lead extraction

Advantages of the Sub Q ICD

Simplified implant procedure with no need for fluoroscopy

Cosmetic advantages, despite its larger size due to the anatomic location in the lateral axilla

Well tolerated

Lack of apparent myocardial damage despite greater shock intensity (80J)

Subcutaneous ICD

Limitations of Sub Q ICD

No pacing capability except post shock pacing ( no anti-tachycardia pacing and no CRT)

Remote monitoring and atrial tachyarrhythmia monitoring not available yet

Pulse generator is larger with anticipated battery life shorter and transvenous devices

Cost is higher than transvenous device

DeMaria et al ESC Council for Cardiology Practice March 2014

Limitations of Sub Q ICD

Pre-implantation screening is mandatory. Must use a transparent plastic tool provided by the company to perform an “ad hoc” EKG skin electrode positioning to verify adequate sensing of subcutaneous signals to avoid double counting of the QRS or T wave over sensing

Up to 7.4% of possible candidates would not be suitable (hypertrophic CM, heavy weight, prolonged QRS duration and an R/T ratio <3 were independently associated with screening failure)

Risks of inappropriate shocks is similar to transvenous ICDs

Risk of under sensing true arrhythmias(VF with low amplitude waves)

Prolonged time to therapy compared to transvenous device (14-18 sec compared to 7-8 sec)

Demaria et al ESC Council for Cardiology practice March 2014

Why is EKG screening necessary for Sub Q ICDS?

Must identify the small number of patients whose Sub Q ICD signals may be unusually challenging for detection and discrimination

Surface EKG is representative of the subcutaneous signal, therefore pre-op screening process was developed to analyze patient’s EKG without the need to first implant the device

Screening process is used to analyze the QRS amplitude, QRS –T wave amplitude ratios, QRS width and morphology consistency in sinus rhythm in multiple positions

EKG screening for SubQ ICD

EKG screening for Sub Q ICD

ACCEPTABLE EKG :Entire QRS complex and trailing T wave are contained within the colored profile

UNACCEPTABLE EKG: Some portion of the QRS complex or trailing T wave extends outside of the colored profile

Brugada EKG

What’s on the horizon?

Leadless pacemakers

MRI compatible ICDs

Size comparison :match stick: loop recorder: leadless pacemaker

Summary