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The EP Show: Right ventricular vs biventricular pacing

Eric Prystowsky MDDirector, Clinical Electrophysiology Laboratory St Vincent HospitalIndianapolis, IN

Bruce Wilkoff MDDirector, Cardiac Pacing/Tachyarrhythmia DevicesCleveland ClinicCleveland, OH

Leslie Saxon MDDirector, Department of ElectrophysiologyUSC University HospitalLos Angeles, CA

Michael Gold MDChief, Division of CardiologyMedical University South CarolinaCharleston, SC

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Right ventricular vs biventricular pacing

Can long-term right ventricular pacing actually hurt the heart?

June 2004

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How to pace?"Systole is better than asystole."

• If the heart needs to be paced, and there is heart block, the ventricle needs to be paced somehow

CONTROVERSY

• Pacing the atrium in AAI mode vs pacing in VVI or DDD modes

• Europeans lead way in promoting atrial pacing over ventricular pacing

WilkoffJune 2004

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The data

Data clear that wall-motion abnormality produced when ventricle is paced

June 2004 - Wilkoff

• Danish observational data suggest there is a mortality benefit with atrial pacing

• DDD vs VVI, as well as other trials, all include ventricular pacing

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DAVID Dual-Chamber and VVI Implantable

Defibrillator

Comparison of ICD therapy with dual-chamber pacing vs ventricular backup

pacing

June 2004

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DAVID trial: DDDR-70 vs VVI-40

programming

End point DDDR-70 (%)

VVI-40 (%)

Relative risk (95% CI)

Event-free survival at 1 year

73.3 83.9 1.61 (1.06-2.44)

Mortality 10.1 6.5 1.61 (0.84-3.09)

CHF hospitalization

22.6 13.3 1.54 (0.97-2.46)

The DAVID trial investigators. JAMA 2002; 288:3115-3123.

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DAVID trial

Pacing really caused a significant detriment to these patients

•The change in mortality and HF was equal to the benefit of amiodarone seen in the original AVID trials

•Large effect on HF and mortality without RV pacing, at least in patients who needed

defibrillators and had ventricular dysfunction

WilkoffJune 2004

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Landmark study

In some ways, the DAVID trial is one of the first randomized pacing trials

• Treatment vs nontreatment group

• First trial to show an isolated effect of DDDR pacing and RV pacing on HF and mortality

June 2004

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•Consistent with DAVID, MADIT II patients with dual-chamber defibrillators had a higher rate of hospitalization for heart failure than those with single-chamber devices

•Consensus emerging that RV pacing may be hurting patients

•Trying now to get the benefit of an atrial lead without

ventricular pacing

Gold

MADIT II

June 2004

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• Resynchronization therapy performed with simultaneous RV and LV pacing; or pace with LV alone

• Most data with biventricular pacing in symptomatic HF patients with conduction disease

Biventricular pacing

June 2004

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Biventricular pacing

• Patients feel better and exercise more, systolic response improves, and possible reverse remodeling

• Sickest patients appear to live longer and require fewer hospitalizations

June 2004

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What about the brady-indicated patient who does not meet criteria for CRT?

Help vs harmWhat is the risk of RV-pacing-induced

left bundle branch block?

How will this hurt the patient in the short and long term?

- Saxon

Biventricular pacing

June 2004

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"I think in some patients, chronic RV pacing will cause left ventricular dysfunction."

• Not a majority

In patients with LV dysfunction but with native left bundle branch block, RV pacing will not likely make that ventricle worse

• May be improved with biventricular pacing, but requires careful evaluation

Saxon

Biventricular pacing

June 2004

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A recurring question

What about the patient with chronic RV pacing and LV dysfunction who comes to the lab for an elective battery replacement?

• Upgrade to CRT represent "half of what I'm doing these days"

• Begin to think about the patient under the criteria of other prophylactic studies, such as MADIT II and SCD-HeFT

June 2004 - Saxon

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How is the LV paced?LV pacing achieved similar to right-sided implants

• LV lead placed into the venous system

• LV branch vein accessed through the coronary sinus great cardiac vein

• Coronary sinus accessed in a retrograde fashion from the lower right atrium

• Guide catheter employed into the great cardiac vein, with lead deployedinto branch vein to pace the left

ventricle

June 2004 - Saxon

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Negative effects of RV pacing

Not only does chronic RV pacing induce LV dyssynchrony, but even if atrial transport is maintained in DDD mode, there is an increased risk of atrial fibrillation, in addition to the increased risk of heart failure

SaxonJune 2004

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Indications for biventricular pacing

INDICATIONS

• Patients with class 3 or 4 heart failure, despite optimal medical treatment

• EF <35%

• Wide QRS interval (at least 120-130 ms)

• Left bundle branch block patient (typically)

June 2004

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"I think the AF data are difficult and confusing."

• Lack of P wave needed to pace ventricle

"The data we do have suggests these patients can benefit if you can achieve frequent, if not continuous, biventricular pacing."

AF data

GoldJune 2004

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Who gets a defibrillator? Two major trials:

SCD-HeFT Sudden Cardiac Death in Heart

Failure Trial

COMPANIONComparison of Medical Therapy,

Pacing, and Defibrillation in Heart Failure

Recent answers

June 2004

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SCD-HeFT mortality data

All-cause mortality

ICD Amiodarone Placebo

3 years (%) 17.1 24.0 22.3

5 years (%) 28.9 34.1 35.8

Bardy G. American College of Cardiology 2004 Scientific Sessions; Mar 7-10, 2004; New Orleans, LA.

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COMPANION: 12-month outcomes

Bristow MR et al. N Engl J Med 2004; 350:2140-2150.

End point OMTa, n=308 (%)

Plus CRT, n=617 (%)

HR(95% CI)

pb Plus CRT/ICD, n=595 (%)

RR(95% CI)

pb

All cause mortality/hospitalization

68 56 0.81(0.69-0.96)

0.015 56 0.80(0.68-0.95)

0.011

All-cause mortality

19 15 0.76(0.58-1.01)

0.06 12 0.64(0.48-0.86)

0.004

a OMT=Optimal medical therapyb p vs optimal medical therapy without device therapyHR=hazard ratioCI=confidence intervals

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SCD-HeFT and COMPANION

"Those studies have certainly made us move more and more toward combining defibrillators with biventricular pacing in a majority of our patients."

Gold

Impact

June 2004

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CRT plus a defibrillator

Is it fair to say that if patients meet the criteria for biventricular pacing, they will also have an indication for a defibrillator?

- Prystowsky

Yes, the clinical data support it.

- Gold

June 2004

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Biventricular pacemaker or defibrillator?

"There is another issue here and it has to do with reimbursement. We have to bring in who is going to pay for this."

• Still some "fuzziness" to NYHA functional class

• How do we treat the NYHA class 2 HF patients?

• Reimbursement decision expected from CMS by September 2004

WilkoffJune 2004

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Nonischemic HF• Very little data to support the use of defibrillators in

dilated nonischemic cardiomyopathy patients

DEFINITE study

• Medically managed HF patients with nonischemic cardiomyopathy implanted with an ICD showed a nonsignificant reduction in all-cause mortality with device therapy

"We're in a little bit of a bind here. We have some good clinical data, but we don't have administrative approval to be putting defibrillators in all these patients."

- Wilkoff

June 2004

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Social issues"There are a number of people that just don't

relate to the concept of having an implantable defibrillator."

• Need to discuss implications, but in general, if presented properly, most patients will want the device; others will refuse

• In ischemic patients, where there is reimbursement, we should be pushing for biventricular defibrillator devices

WilkoffJune 2004

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Patient selection

OTHER INDICATORS

• Wall motion indices as possibly superior to QRS duration?

• Response rates, in terms of clinical improvement, can be frustrating, especially in patients who meet standard criteria

June 2004

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Other indicatorsThe wider the QRS, the greater the

probability of benefit

• But QRS is a surrogate marker so there is a need to look for other, more direct, measures of dyssynchrony

• Echo and nuclear measures as possible predictors of patient benefit

GoldJune 2004

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More data needed

"I think this is an evolving field that's very interesting in trying to select these patients, but unfortunately we don't have long-term outcome data using these measures."

June 2004 - Gold

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Not there yetMechanical dysfunction identified typically by an

ECG

"It's not really the disease. It is a surrogate for the wall motion abnormality that we're trying to correct with an electrical answer."

"It is likely that we're going to have better measures for dyssynchrony and we're going to find better ways of identifying patients."

- Wilkoff

June 2004

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The future

• Moving toward resynchronization in a larger group of patients

• Need for studies to determine whether various imaging indices can prospectively identify responders

"Right now, these imaging methods are really experimental and should not be used as selection criteria."

SaxonJune 2004

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The futureIssue of whether the ventricle can

resynchronized with LV pacing alone is fascinating

• Early European data showing that LV pacing alone can improve the "feel-good" parameters as much as biventricular pacing

• Echo studies preliminary, but comparable

• QRS actually widens

June 2004

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The future

• New studies in brady-indicated patients randomized--regardless of LV function--to biventricular/LV pacing vs RV pacing alone

• Issue of who needs defibrillation has been worked out by the ICD trials that will trump indications for these patients currently under FDA approval

June 2004

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Off-label use

BEDSIDE PRACTICE

"You can't always wait for trials."

- Prystowsky

"I'm maybe more conservative than others, having been through the wars of biventricular pacing."

- Gold

June 2004

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Off-label use

"In general, if I have a patient with preserved LV function who is going to be pacing, whether because I've created complete heart block with an ablation or because they have intrinsic AV node disease, I will still tend to RV pace them. I know that's a safe, simple, reliable system."

GoldJune 2004

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The guy in the corner"Am I the only person who is pacing some

selected patients with a biventricular system that aren't in class 3 or 4 heart failure?"

- Prystowsky

"No, I'm doing it, Eric."

- Saxon

• PAVE trial showed improved exercise capacity in less symptomatic patients who were implanted with a biventricular device

June 2004

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Caution urged

• However, subanalysis in PAVE showed that the improvement was only in patients with EF <40%

• There was no benefit in patients who had preserved EF

• Study overall had a statistically significant end point, but subgroups had

disparate results

GoldJune 2004

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Not hypothetical

"These are not general and new guidelines. These are totally off the guidelines."

But the technology is available and it is not hypothetical. Clearly, it is a patient-by-patient discussion

PrystowskyJune 2004