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CRT’S, ICD’S & AF. No its not a gynae topic !

This article discusses the rationale for cardiac resynchronization therapy (CRT) and the use of implantable cardioverter-defibrillators (ICDs) in patients with heart failure. It provides an overview of key clinical trials and their results.

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CRT’S, ICD’S & AF. No its not a gynae topic !

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  1. CRT’S, ICD’S & AF.No its not a gynae topic ! Dr MB Davidson University of Witwatersrand. Hannes Meyer Reg Forum: 12/04/08

  2. Rationale for Cardiac Resynchronisation • 30-50% prevalence of IV conduction delay among patients with Heart Failure (HF). • Intraventricular Conduction Delay is associated with dyssynchronous LV contraction caused by regional delays in electrical activation of chamber. • Results in poor coordination of ventricular contraction & relaxation. • Results in reduced systolic function & increased end systolic volume. • Enhances the hemodynamic consequences of chronic LV systolic dysfunction. (ie. LV remodelling) • Biventricular stimulation synchronises the activation of the Intraventricular Septum & the LV free wall improving & coordinating LV systolic function.

  3. MUSTIC TrialEffects of multisite biventricular pacing in patients with heart failure and intraventricular conduction delay.S Cazeu, C Leclercq, et al. NEJM. 2001: 344; 12 • Single-blind randomized control cross-over trial. • 67 patients responses were compared over two 3-month periods. Atrio-Biventricular Pacing vs None. • Admission criteria: • Severe CCF (NYHA III) due to LV Systolic dysfunction. • EF < 35% • LVEDD > 60 mm. • Sinus rhythm c QRS complex > 150 msec. • No other indication for a pacemaker. • Primary End Points: • Distance walked in 6 minutes. • Quality of life (Minnesota Living with HF Questionnaire) • Secondary End Points: • Peak O2 uptake, Hospitalisation, Death & Patient’s Preference.

  4. MUSTIC TrialResults: 6-Minute walk test23% Longer (P<0.001) than INACTIVE

  5. MUSTIC TrialResults: Minnesota ScoreDecreased by 32% with pacing (P<0.001)

  6. MIRACLE TrialCardiac Resynchronization in Chronic Heart Failure. W Abraham, W Fisher, et al. NEJM. 2002: 346; 24 • A Multi-Centre Double-blind randomized control trial comparing Atrio-Biventricular Pacing vs control over a period of 6 months. • 453 patients randomised to either arm (228 CRT vs 225 control). • Admission criteria: • Severe CCF (NYHA III or IV) due to Ischemic or Non, Dilated CMO. • EF < 35% • LVEDD > 55 mm. • QRS complex > 130 msec. • 6-Minute walk test of 450m or less. • Primary End Points: • NYHA Class. • Distance walked in 6 minutes. • Quality of life (Minnesota Living with HF Questionnaire) • Secondary End Points: • Peak O2 consumption, Time on treadmill, LVEF, LVEDD, Severity of MR, duration of QRS interval & clinical response.

  7. MIRACLE TrialResults:

  8. MIRACLE TrialResults:

  9. MIRACLE TrialResults:

  10. MIRACLE TrialRisk of Death or Hospitalisation was 40% less in the CRt group (P = 0.03)

  11. Implantable Cardioverter Defibrillators: • Sudden Cardiac Death claims 300,000 lives in the USA per year. • 80% of cases are due to the abrupt onset of VTach that progresses to VF. • Unsustained VTach in the setting of previous MI is associated with a 2-year mortality of 20%.

  12. MADIT II TrialProphylactic Implantation of a defibrillator in patients with myocardial infarction & reduced ejection fraction. A Moss, W Zarebra, et al. NEJM. 2002: 346; 24 • A Multi-Centre Double-blind randomized control trial comparing ICD vs conventional drug treatment. • 1232 patients randomised in a 3:2 ratio (742 ICD vs 490 control). • Admission criteria: • Experienced an AMI 30 days prior to enrolment. • LVEF < 30%. • Exclusion Criteria: • Prior cardiac arrest or syncope unrelated to AMI. • NYHA class IV at enrolment. • CABG or PCI revascularisation < 3 months prior to enrolment. • Use of antiarrhytmic agents (except for atrial arrhytmias). • Other comorbidity with decreased life-expectancy. • Primary End Point: Death from any cause.

  13. MADIT II TrialResults: 31% Reduction in mortality Mortality: Conventional therapy: 97 of 490 (19.8%) Vs ICD Group: 105 of 742 (14.2%) Hazard Ratio:(95% CI) 0.69 (0.51 – 0.93) P = 0.016

  14. DINAMIT TrialProphylactic use of an Implantable Cardioverter-Defibrillator After AMI. S Hohnloser, K Kuck, et al. NEJM. 2004: 351; 24 • A randomized open-label comparison of ICD therapy vs none 6 to 40 days after an acute myocardial infarction. • 674 patients were enrolled & randomised (332 ICD vs 342 control). • Admission criteria: • Recent Myocardial Infarction (6 to 40 days prior to enrolment) • LVEF < 35% • LVEDD > 55 mm. • Impaired cardiac autonomic function (based on 24hr Holter ECG). • Exclusion criteria: • NYHA Class IV. • CABG or 3 vessel PCI performed since AMI or planned within 4 weeks. • Requirement for an ICD or prior implantation of a pacemaker. • Primary End Point: Death from any cause.

  15. DINAMIT TrialResults: Mortality (120): Control Group: 58 of 342 (17%) Vs ICD Group: 62 of 332 (18.7%) Hazard Ratio:(95% CI) 1.08 (0.76 – 1.55)

  16. SCD-HeFT TrialAmiodarone or an ICD for Congestive Heart Failure. G Bardy, K Lee, et al. NEJM. 2005: 352; 3 • A randomized double blind study comparing conventional therapy & placebo vs conventional therapy & Amiodarone vs conventional therapy & shock-only single lead ICD. • 2521 patients enrolled (847 placebo vs 845 amiodarone vs 829 ICD). • Admission criteria: • NYHA II-III chronic stable CHF due to ischemic or non-ischemic cause. • LVEF < 35% • Primary End Point: Death from any cause.

  17. SCD-HeFT TrialICD resulted in a 23% reduction in mortality

  18. COMPANION TrialCardiac-Resynchronisation Therapy with or without an Implantable Defibrillator in Advanced Chronic Heart Failure. M Bristow, L Saxon, et al. NEJM. 2004: 350; 21 • A multi-centre randomised control trial comparing Optimal Medical Therapy vs CRT vs CRT with a Pacemaker-Defibrillator. • 1520 patients enrolled across 128 US centres in a 1:2:2 ratio (308 Medical Therapy vs 617 CRT vs 595 CRT-ICD). • Admission criteria: • NYHA III or IV HF due to Ischemic or Nonischemic CMO. • LVEF < 35% • QRS complex > 120 msec. • Sinus rhythm c PR interval > 150 msec. • No indication for a pacemaker or ICD. • Hospitalisation for HF within previous 12 months. • Primary End Point: • Composite of Death or Hospitalisation from any cause.

  19. Companion TrialResults:

  20. Companion TrialResults:

  21. DECREASE-HF TrialReduced Ventricular Volumes and Improved Systolic Function with CRT. R Rao, U Kumar, et al. Circulation. 2007; 115: 2136-2144 • A randomised double-blind study comparing Sequential BiV pacing vs Simultaneous BiV pacing vs LV pacing alone. • 306 patients enrolled (99 LV pacing vs 104 Sequential BiV pacing vs 100 Simultaneous BiV pacing). • Admission criteria: • NYHA III or IV HF due to Ischemic or Nonischemic CMO. • LVEF < 35%. • QRS complex > 150 msec. • Life-expectancy > 6 months. • Primary End Points: • Peak Oxygen Consumption. • LV end-systolic dimension.

  22. DECREASE-HF TrialResults:

  23. DECREASE-HF TrialResults:

  24. RethinQ studyCardiac Resynchronisation therapy in Heart Failure with Narrow QRS Complexes. J Beshai, R Grimm, et al. NEJM. 2007: 357; 24 • A randomised double-blind clinical study comparing the efficacy of CRT vs control in patients with narrow QRS complex & Echo evidence of dyssynchrony. • 172 pt’s enrolled across 34 centres (87 CRT vs 85 control.) • Admission criteria: • NYHA III or IV HF due to Ischemic or Nonischemic CMO. • LVEF < 35%. • QRS complex < 130 msec. • Evidence of mechanical dyssynchrony on Echo Tissue Dopplers. • Primary End Point: • Improvement in Peak Oxygen Consumption at 6 months. • Secondary End Points: • Improvement in Quality of Life score at 6 months. • Improvement in NYHA at 6 months.

  25. RethinQ StudyResults:

  26. CRT & ICD’s in conclusion • Cardiac Resynchronisation Therapy has proven benefits: • It decreases Mortality (Hence improves Survival) • It improves Quality of Life. • It improves Exercise Capacity & Functional Status. • It decreases the need for Hospitalisation. • It decreases LV Volumes & improves LV Systolic Function (LVEF.) • It decreases the degree of Mitral Regurgitation. • It leads to LV Reverse Remodeling. • Implantable Cardiovertor-Defibrillators have proven benefit: • They decrease Mortality.

  27. in conclusion • Thus CRT & ICD is indicated in the following pt’s: • NYHA Class III or IV Heart Failure due to Ischemic or Non-Ischemic Dilated CMO. • LVEF < 35% • Prolonged QRS interval > 120 msec. • In conjunction with Optimal Medical Therapy. • What is the role of the Cardiac Surgeon ?

  28. Atrial FibrillationIntroduction. • AF is the most common cardiac arrhythmia. • 2.2 Million in USA & 5.0 Million worldwide. • 1% of general population & 6% of those over 65 years. • In the USA accounts for 875,000 hospitalisations and costs $6.6 Billion. • Risk of stroke associated with AF is 5-12% per year. • Risk of stroke may be reduced by warfarin by 37-86%; at risk of bleeding of 0.5-2.8% per year. • Chronic AF is associated with progressive Atrial Myocardial Fibrosis. • End Stage result is Tachycardia Induced CMO.

  29. Atrial FibrillationDefinitions & PathoPhysiology: • Pathophysiology: • Multiple Macro-Reentry Wavelets. • Focal Triggers Theory. • Classification: • Paroxysmal: AF terminates spontaneously. • Persistent: AF can be converted with therapy. • Permanent: AF is refractory to treatment.

  30. Atrial FibrillationThe Gold Standard - Cox-Maze III Procedure. • Indications for surgery: • Symptomatic AF with Failed Medical Therapy. • Not performed for Heart Failure unless the Heart Failure can be directly attributed to AF. • Operative Technique: • Multiple incisions made in the atria that interrupt the conduction routes of the most common reentrant circuits. • Redirects the SA-node impulse to the AV-node along a specified route with multiple blind-ending alleys off the main conduction route to preserve atrial contractility.

  31. Atrial FibrillationCox-Maze III Procedure. J Cox, R Scheusller, et al. Semin Thor & CVS. 2000; 12: 2-14 • Cox et al: • 346 Patients. 299 Had Maze III. • 2% Operative Mortality. • Overall success rate of 99% in sinus rhythm. • No permanent damage to SA node. • Functional LA in 93% & RA in 99%. • Schaff et al: • 221 Maze procedures. 75% concomitant cardiac surgery. • Early mortality was 1.4% incl 26 patients c depressed LVEF. • 85-90% were free of AF. • Mean LVEF increased by 31 to 53%.

  32. AFEnergy sources in clinical use for the ablation of AF.G Comas, Y Imren, et al. Semin Thor & CVS. 2007; 19: 16-24

  33. Atrial FibrillationModified-Maze III Procedure.

  34. Atrial Fibrillation AF And Concomitant cardiac Surgery. • Present in 50% of patients undergoing Mitral valve surgery. • Present in 1-6% of patients undergoing CABG or Aortic valve surgery. • The addition of a traditional Cox-Maze procedure does not increase operative mortality or morbidity. • However 5-10% risk of need for a pacemaker especially if pre-existing sinus node dysfunction. • Restoration of sinus rhythm is reported in 70-96%. • Greater LA diameter, longer duration of pre-op AF & advanced patient age all increase the prevalence of late AF. • Hence Maze procedure is a safe addition to concomitant cardiac surgery. • Also indicated for severely symptomatic, drug-refractory AF

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