Importance of Shock Reduction
Data from published studies reveal that up to 21% of ICD patients receive inappropriate shocks.1-4
Detail Incidence of inappropriate shocks in ICD patients
Reducing shocks has been shown to improve ICD patients’ quality of life and increased ICD acceptance.
- For patients, simply the fear of shocks can be disruptive to a normal, active life5,6
- The Canadian ICD Study (CIDS) found that patients randomized to ICD therapy (versus those given amiodarone) had better quality of life until they received five shocks7
- Some studies have demonstrated that experiencing just one shock causes temporary reductions in patients’ quality of life7
Avoiding shocks is important for:
- Reducing pain and anxiety, and increasing patients’ acceptance of ICDs8,9
- Reducing healthcare burden and improving patient quality of life8
- Improving survival/heart failure10
- Kadish A, Dyer A, Daubert JP, et al., for the Defibrillators in Non-Ischemic Cardiomyopathy Treatment Evaluation (DEFINITE) Investigators. Prophylactic defibrillator implantation in patients with nonischemic dilated cardiomyopathy. N Engl J Med. 2004;350:2151-2158.
- Daubert JP, Zareba W, Cannom DS, et al., for the MADIT II Investigators. Inappropriate implantable cardioverter-defibrillator shocks in MADIT-II: frequency, mechanisms, predictors, and survival impact. J Am Coll Cardiol. 2008;5:1357-1365.
- Poole JE, Johnson GW, Hellkamp AS, et al. Prognostic importance of defibrillator shocks in patients with heart failure. N Engl J Med. September 4, 2008;359:1009-1017.
- Mitka M. New study supports lifesaving benefits of implantable defibrillation devices. JAMA. 2009;302:134-135.
- Sears SF JR, Todaro JF, Lewis TS, et al. Examining the psychosocial impact of implantable cardioverter defibrillators: a literature review. Clin Cardiol. 1999;22:481-489.
- Sears SF Jr, Conti JB. Understanding implantable cardioverter defibrillator shocks and storms: medical and psychosocial considerations for research and clinical care. Clin Cardiol. 2003;26:107-111.
- Irvine J, Dorian P, Baker B, et al. Quality of life in the Canadian Implantable Defibrillator Study (CIDS). Am Heart J. 2002;144:282-289.
- Wathen MS, DeGroot PJ, Sweeney MO, et al, for the PainFREE RX II Investigators. Prospective randomized multicenter trial of empirical antitachycardia pacing versus shocks for spontaneous rapid ventricular tachycardia in patients with implantable cardioverter-defibrillators. Circulation. 2004;110:2591-2596.
- Ahmad M, Bloomstein L, Roelke M, et al. Patients’ attitudes toward implantable defibrillator shocks. PACE. 2000;23:934-938.
- Sweeney MO, Sherfesee L, DeGroot PJ, et al. Differences in effects of electrical therapy type for ventricular arrhythmias on mortality in implantable cardioverter-defibrillator patients. Heart Rhythm. 2010;7:353-360.
Medtronic developed its exclusive SmartShock Technology based on more than 20 years of experience in shock reduction. Consisting of six exclusive algorithms that discriminate true lethal arrhythmias from other arrhythmic and non-arrhythmic events, SmartShock Technology dramatically reduces the incidence of inappropriate shocks while maintaining sensitivity.1,2
Detail Fewer inappropriate shocks
With SmartShock Technology, 98% of ICD patients are free of inappropriate shocks at 1 year1 and 92% remain free of inappropriate shocks at 5 years.1
Detail Time to first in appropriate shock
Detail SmartShock Techology algorithms
The six algorithms in SmartShock Technology address all major causes of inappropriate shocks1:
T Wave Discrimination
Identifies T Wave oversensing and provides ability to withhold therapy delivery without compromising VT/VF detection sensitivity.
- New approach to T Wave oversensing (TWOS)
- Frequency analysis versus manual sensitivity adjustment
- Fully automatic
- Does not require an initial shock for TWOS
- No compromise on VF detection sensitivity
T Wave Discrimination algorithm
Lead Integrity Suite
Combines two algorithms that detect, alert, and withhold inappropriate therapy for lead failure.
Lead Integrity Alert
Provides advance warning for lead fracture and extends the VF detection time
Lead Noise Discriminator + Alert
Identifies oversensing due to noise artifacts and provides ability to withhold therapy
- No compromise of VT/VF detection sensitivity
- Notifies clinician to potential lead noise
Lead Integrity Suite algorithm
PR Logic + Wavelet
Combines morphology and A-V pattern recognition to better discriminate against all types of SVTs – even the very fast ones.
Effectively discriminates sinus tachycardia and most atrial fibrillation/atrial flutter
Uses EGM morphology to improve SVT discrimination (i.e., conducted AF and sudden onset SVT)
Discrimination in the VF Zone (Nominal)
- SVT limit = 260 ms
- VF high-rate timeout
PR Logic + Wavelet algorithm
- Better identifies that a tachycardia has been terminated with ATP or spontaneously during the charge and aborts the shock
- Avoids inappropriate shocks for single PVCs or single fast events at the end of the charge
Confirmation + algorithm
- Volosin KJ, Exner DV, Wathen MS, Sherfesee L, Scinicariello A, Gillberg JM. Combining shock reduction strategies to enhance ICD therapy: A role for computer modeling. J Cardiovas Electrophysiol. Published online October 11, 2010.
- Protecta Clinical Study, Medtronic data on file.