CRT - Indications and Response to Therapy

CRT - Indications and Response to Therapy

06 April 2019

Raja Selvaraj, JIPMER

Introduction

What is CRT ?

A third of patients with advanced heart failure have a prolonged QRS duration
Electrical dyssynchrony associated with mechanical dyssynchrony
CRT is a form of multisite ventricular pacing that corrects the dyssychrony
Improvement in systolic function, remodeling of the ventricle, reduction of MR
Improvement in functional capacity

Illustrative case

45 year old male
DOE NYHA III
LVEF 18%
Normal coronaries

Start with example of a patient we saw 9 years back Very symptomatic

CRT implant

Echo - Pre and Post (3 months)

Now - 8 years later

NYHA I
LVEF 55%
Beta blocker and ACEI

Prognosis would have been poor without crt in this patient Can be truly transformative in the right patients Therefore choosing the right patient is critical

Indications

Guidelines based

ACC AHA guidelines
Focused update
EHRA
ESC

ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities. Circulation. 2008;117:e350–e408
2012 ACCF/AHA/HRS focused update incorporated into the ACCF/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities. J Am Coll Cardiol 62:e6–e75
2013 ESC / EHRA guidelines on cardiac pacing and cardiac resynchronization therapy. Eur Heart J 34:2281–2329.
2016 ESC guidelines for the diagnosis and treatment of acute and chronic heart failure. Eur Heart J 18:891–975

Rely on a lot of guidelines. Device guidelines from ACC is from 2008, but there was a focused update in 2013. EHRA guidelines also in 2013, ESC guidelines in 2016

Class I Indication

LVEF < 35%

LBBB

QRSd > 150

NYHA II / III / IV

Sinus rhythm

When all these are present, it signifies someone very likely to respond When any of these are absent, the indications veer from class I to varying degrees

In addition

Should be receiving guideline directed medical therapy
Interval more than
- 3 months from initial diagnosis
- 40 days after MI
- 3 months after revascularization

Beyond class I guidelines

QRS duration < 150 ms

qrs<150.png

Stavros Stavrakis et al. The Benefit of Cardiac Resynchronization Therapy and QRS Duration: A Meta‐Analysis. JCE 2012;23:163-168

QRS duration < 150 ms

qrs>150.png

Narrow QRS - QRSd < 120 ms

Echo identified mechanical dyssynchrony does not predict response
Class III with QRSd < 120 / 130 ms

Echo CRT - Ruschitzka F., Abraham W.T., Singh J.P., et al. (2013) Cardiac-resynchronization therapy in heart failure with a narrow QRS complex. N Engl J Med 369:1395–1405
Lesser earth - Thibault B., Harel F., Ducharme A., et al. (2013) Cardiac resynchronization therapy in patients with heart failure and a QRS complex <120 milliseconds: the Evaluation of Resynchronization Therapy for Heart Failure (LESSER-EARTH) trial. Circulation 127:873–881

QRSd 120-130 ms

ACC / AHA - Class IIa (2012)
ESC EHRA - Class I (2013
ESC HFA - Class III (2016)

ECHO CRT study

NYHA III or IV
LVEF < 35%
QRSd < 130 ms
Echo evidence of dyssynchrony

Frank Ruschitzka et al. Cardiac-Resynchronization Therapy in Heart Failure with a Narrow QRS Complex. N Engl J Med 2013; 369:1395-1405

800 + patients randomized 1:1 to CRTD with active CRT and CRTD with pacing turned off Terminated prematurely because of excess deaths

ECHO CRT study

No decrease in composite endpoint (death + hf hospitalization) Excess of deaths

Non LBBB wide QRS

Class IIa when QRSd > 150 and NYHA III / IV
Class IIb - NYHA II, QRSd > 150
Class IIb - NYHA III, QRSd < 150

NYHA Class IV

Most patients in trials are in NYHA III
Overall, NYHA IV comprise 10% or less
Most of these are ambulatory IV
Not useful in acute decompensated heart failure

Evidence is available only for ambulatory class IV and even that is sparse

NYHA Class I

Class IIb indication in ischemic CMP with EF < 30% and LBBB, QRSd>150
Based on benefit with CRTD in MADIT CRT trial (15% of patients were NYHA I)

Zareba W., Klein H., Cygankiewicz I., et al. (2011) Effectiveness of cardiac resynchronization therapy by QRS morphology in the Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy (MADIT-CRT). Circulation 123:1061–1072.

The guidelines are off on this one. Logically NICM should be a setting where this may work. However, evidence is there only for iCM

Atrial fibrillation

Class IIa
Other indications met
Ensure near 100% pacing
Will need good pharmacologic rate control or AV node ablation

Pacing requirement in heart failure or reduced LVEF

Reduced LVEF
Heart failure
Pacing requirement > 40%

BLOCK HF - Curtis A.B., Worley S.J., Adamson P.B., et al. (2013) Biventricular pacing for atrioventricular block and systolic dysfunction. N Engl J Med 368:1585–1593
DAVID - Sharma A.D., Rizo-Patron C., Hallstrom A.P., et al. (2005) Percent right ventricular pacing predicts outcomes in the DAVID trial. Heart Rhythm 2:830–834.

Ischemic heart disease

Not differentiated in guidelines
Clinical / remodeling response less compared to NICM
Survival benefit of CRTD over ICD in trials
Predominantly used in North America (>50% of all CRT)

Heart failure, LBBB, EF 35-50%

Evolution of CRT usage

Summary

Summary

Better selection = less non responders
Situations where trial may be considered although chance of response less
Should be discussed with patient

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CRT - Indications and Response to Therapy 06 April 2019 Raja Selvaraj, JIPMER