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Device therapy –Diagnostic and Therapeutic Marilyn M. Cox M.D., F.A.C.C. Overview of Device Therapy Implantable loop recorders Pacemakers Implantable Cardioverter-DefibrillatorsSingle, 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 years cardiac monitoring for up to 3 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 months ICM 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 antitachycardia 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 electrode ICD is connected to a subcutaneous 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 MRI pacemakers compatible ICDs Size comparison :match stick: loop recorder: leadless pacemaker Summary
