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CRT’S, ICD’S & AF.
No its not a gynae
topic !
Dr MB Davidson
University of Witwatersrand.
Hannes Meyer Reg Forum: 12/04/08
Rationale for Cardiac
Resynchronisation
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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.
MUSTIC Trial
Effects of multisite biventricular pacing
in patients with heart failure and
intraventricular conduction delay.
S Cazeu, C Leclercq, et al. NEJM. 2001: 344; 12
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Single-blind randomized control cross-over trial.
67 patients responses were compared over two 3-month periods.
Atrio-Biventricular Pacing vs None.
Admission criteria:
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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)
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Secondary End Points:
– Peak O2 uptake, Hospitalisation, Death & Patient’s Preference.
MUSTIC Trial
Results: 6-Minute walk test
23% Longer (P<0.001) than INACTIVE
MUSTIC Trial
Results: Minnesota Score
Decreased by 32% with pacing (P<0.001)
MIRACLE Trial
Cardiac Resynchronization in Chronic
Heart Failure.
W Abraham, W Fisher, et al. NEJM. 2002: 346; 24
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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:
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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)
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Secondary End Points:
– Peak O2 consumption, Time on treadmill, LVEF, LVEDD, Severity of MR,
duration of QRS interval & clinical response.
MIRACLE Trial
Results:
MIRACLE Trial
Results:
MIRACLE Trial
Results:
MIRACLE Trial
Risk of Death or Hospitalisation
was 40% less in the CRt group (P = 0.03)
Implantable Cardioverter
Defibrillators:
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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%.
MADIT II Trial
Prophylactic Implantation of a
defibrillator in patients with myocardial
infarction & reduced ejection fraction.
A Moss, W Zarebra, et al. NEJM. 2002: 346; 24
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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%.
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Exclusion Criteria:
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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.
MADIT II Trial
Results: 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
DINAMIT Trial
Prophylactic use of an Implantable
Cardioverter-Defibrillator After AMI.
S Hohnloser, K Kuck, et al. NEJM. 2004: 351; 24
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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:
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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.
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Primary End Point: Death from any cause.
DINAMIT Trial
Results:
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)
SCD-HeFT Trial
Amiodarone or an ICD for Congestive Heart
Failure.
G Bardy, K Lee, et al. NEJM. 2005: 352; 3
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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%
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Primary End Point: Death from any cause.
SCD-HeFT Trial
ICD resulted in a 23% reduction
in mortality
COMPANION Trial
Cardiac-Resynchronisation Therapy with
or without an Implantable Defibrillator
in Advanced Chronic Heart Failure.
M Bristow, L Saxon, et al. NEJM. 2004: 350; 21
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A multi-centre randomised control trial comparing Optimal
Medical Therapy vs CRT vs CRT with a PacemakerDefibrillator.
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:
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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.
Companion Trial
Results:
Companion Trial
Results:
DECREASE-HF Trial
Reduced Ventricular Volumes and
Improved Systolic Function with CRT.
R Rao, U Kumar, et al. Circulation. 2007; 115: 2136-2144
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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:
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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.
DECREASE-HF Trial
Results:
DECREASE-HF Trial
Results:
RethinQ study
Cardiac Resynchronisation therapy in
Heart Failure with Narrow QRS Complexes.
J Beshai, R Grimm, et al. NEJM. 2007: 357; 24
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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:
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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.
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Secondary End Points:
– Improvement in Quality of Life score at 6 months.
– Improvement in NYHA at 6 months.
RethinQ Study
Results:
CRT & ICD’s in
conclusion
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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.
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Implantable Cardiovertor-Defibrillators have
proven benefit:
– They decrease Mortality.
in conclusion
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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.
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In conjunction with Optimal Medical Therapy.
What is the role of the Cardiac Surgeon ?
Atrial Fibrillation
Introduction.
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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.
Atrial Fibrillation
Definitions & PathoPhysiology:
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Pathophysiology:
– Multiple Macro-Reentry
Wavelets.
– Focal Triggers Theory.
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Classification:
– Paroxysmal: AF terminates
spontaneously.
– Persistent: AF can be converted
with therapy.
– Permanent: AF is refractory to
treatment.
Atrial Fibrillation
The Gold Standard - Cox-Maze III Procedure.
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Indications for surgery:
– Symptomatic AF with Failed Medical Therapy.
– Not performed for Heart Failure unless the Heart Failure
can be directly attributed to AF.
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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.
Atrial Fibrillation
Cox-Maze III Procedure.
J Cox, R Scheusller, et al. Semin Thor & CVS. 2000; 12: 2-14
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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%.
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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%.
AF
Energy
sources
in
clinical
use for
the
ablation
of AF.
G Comas,
Y Imren,
et al. Semin
Thor & CVS.
2007; 19: 16-24
Atrial Fibrillation
Modified-Maze III Procedure.
Atrial Fibrillation
AF And Concomitant cardiac Surgery.
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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