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SCD and Misc : Cardiology

  • Subcutaneous
    • Not used if patient has a current or future indication for pacing 
    • Transvenous is better for monomorphic VT 
  • Transvenous 
    • RV coil (anode +)
    • SVC coil (cathode -)
      • Note: generator is also cathode -
  • ICDs handle VT and VF differently 
  • Question:
    • How does device differentiate between SVT and VT?
      • Answer: By looking into following features 
        • Onset
        • Stability
        • Morphology
        • V-A Relationship
    • Cardiac Sarcoid
    • HC
  • Note: Remote monitoring actually helps in mortality benefit
    • Likely mechanism:
      • Early detection of A fib
      • Early detection of mis-firing or appropriate firing, and bringing these patients  identifying the cause and timely optimization of medical therapy may be the reason for improve survival advantage
        • Note: Shocks themselves are associated with poor longterm outcome. So, we have to avoid any unnecessary  shocks. 
Pacemaker and ICD sense differently 
  • Understanding how each sense the abnormality is the key in understanding pacemaker or ICD 




  • Primary prevention of SCD after MI 
    • Late Post-MI Trials
      • MADIT (1996)
        • Prior MI 
        • NSVT on monitoring
        • LVEF (≤35 percent)
        • Inducible sustained monomorphic VT during electrophysiology study (EPS) that was also inducible after administration of intravenous procainamide
      • MUSTT (1999)
        • Prior MI (4 days post MI to 3 yrs prior)
        • Asymptomatic NSVT  (at least 4 days post MI )
        • EF < 40 
        • Inducible Sustained VT during EPS in a patient with NSVT
        • No history of Sustained VT or V tach (Secondary prevention) 
      • MADIT2 (2002)
        • Prior MI (>30 days of MI or > 3 months of CABG
        • EF <30
      • CABG Patch Trial (1997 NEJM)
        • Severe CAD requiring surgical revascularization
        • LVEF <36 percent
        • Abnormal signal-averaged electrocardiogram
        • No history of sustained ventricular tachyarrhythmia or syncope
      • SCD HeFT (2005 NEJM) 
        • > 40 days post MI 
        • NYHA II-III, 
        • EF < 35
        • CHF present for at least 3 mth prior to randomization with optimal medical management 
      • Bottom line
      • SCE HeFT criteria (No need to fulfill other electrical criteria of MADIT-I due to its absence in SCD HeFT and still had benefit) 
      • MUSTT Trial Data still valid due to EF < 40 % as inclusion criteria 
        • Vs. SCD HeFT: less severe patients but high risk on further Elecrophysiological Study
      • MADIT - II still valid as it was for EF < 30 % and NYHA Class I patients 
        • Vs. SCD HeFT: Less symptoms but higher risk by EF
    • Early POST-MI 
      • DYNAMIT
      • IRIS 
  • Non-ischemic Cardiomyopathy
    • SCDHeFT (had both patient population) Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT)
      • Amiodarone or an Implantable Cardioverter–Defibrillator for Congestive Heart Failure
      • 2521 patients, half of whom had nonischemic systolic heart failure. 
      • The only randomized trial involving patients with nonischemic systolic heart failure in which a significant benefit with regard to all-cause mortality
      • In patients with NYHA class II or III CHF and LVEF of 35 percent or less, amiodarone has no favorable effect on survival, whereas single-lead, shock-only ICD therapy reduces overall mortality by 23 percent.
      • However, the positive effect of ICD treatment was confined to patients in NYHA class II, and no patients received concomitant CRT. In addition, medical treatment for heart failure has changed since SCD-HeFT was conducted. Only 69% of enrolled patients received beta-blockers at baseline, 20% of patients received a mineralocorticoid-receptor antagonist, and no patients received concomitant CRT 
      • enrolled patients between 1997 and 2001, and 
    • The Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure (COMPANION) study 
        • 1520 patients
        • New York Heart Association (NYHA) class III or IV heart failure 
        • medical therapy, a cardiac re- synchronization therapy (CRT) pacemaker, or a CRT defibrillator, 
        • significantly lower all-cause mortality in association with a CRT defibrillator than with medical treatment alone, but a CRT defibrillator was not shown to be superior to a CRT pacemaker 
    • The Cardiomyopathy Trial (CAT)
      • 2002
      • Primary Prevention of Sudden Cardiac Death in Idiopathic Dilated Cardiomyopathy
      • This trial did not provide evidence in favor of prophylactic ICD implantation in patients with DCM of recent onset and impaired left ventricular ejection fraction.
      • Patients were eligible if they were between 18 and 70 years of age, had symptomatic DCM for ≤9 months and impaired LV function (LVEF ≤30% obtained during LV angiography), and were in NYHA class II or III. Coronary artery disease (coronary stenosis >70%) had to be excluded by angiography. Patients with a history of prior myocardial infarction, myocarditis, or excessive alcohol consumption were not included in the trial

    • AMIOVIRT  
      • Amiodarone versus implantable cardioverter-defibrillator:randomized trial in patients with nonischemicdilated cardiomyopathy and asymptomatic non sustained ventricular tachycardia
      • Mortality and quality of life in patients with NIDCM and NSVT treated with amiodarone or an ICD are not statistically different. There is a trend towards a more beneficial cost profile and improved arrhythmia-free survival with amiodarone therapy
      • JACC 2003
      • enrolled patients between 1998 and 2002, 
      • included a larger proportion of patients who received beta-blockers (85%) but, again, no patients who received CRT 
    • DANISH Investigators (NEJM 2016)
      • A non-ischemic cause of heart failure was usually determined by coronary angiography, although a normal computed tomographic (CT) angiogram or nuclear myocardial perfusion imaging study was acceptable 
  • Secondary Prevention of SCD
    • AVID (1997)
      • EF <  40 
    • CASH (2000)
    • CIDS (2000)





Patient with Remote MI 


AVID: Secondary Prevention


  • Slide on incidence of SCD population and patient studied by primary prevention RCT 
  • Usually STEMI is not seen in normal ECHO 
  • Polymorphic VT are mostly ischemic 
  • Paper
    • 2015 Heart and Rhythm management of postural tachycardia syndrome .... 2015 

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