BLOCK HF trial

Improvements in Clinical outcome with biventricular versus Right

ventricular Pacing

The Block HF study

JACC May 2016

Dr Joura Vishal

Introduction • Heart failure : end stage of various cardiac

conditions

• Refractory heart failure : symptoms at rest inspite of diet , fluid modifications and Optimal medical therapy ( OMT )

• Affects 2.5 % in United states and european countries

2.5 to 5 million in India

Introduction • Systolic heart failure may have - intraventricular dyssynchrony - interventricular dyssynchrony - atriventricular dysnchrony

These patients are at high risk of refractory heart failure and suden cardiac death Baldasseroni et al Am Heart J 2002

Introduction

Cardiac resynchronization therapy • minimises regional left ventricular delay • Reduces Mitral regurgitation • Normalises neurohormonal factors

Thus altering the natural history of disease Mc Alister FA et al JAMA 2007

Introduction

Biventricular pacing is a/w - improved QOL - increased functional capacity - reducing hospitalization - Improved survival

The Block HF trial

RV pacing lead to worse clinic outcomes compared to low rate ventricular pacing in patients with pacemakers and ICD who have intact AV conduction

In AV block pacing is required all the time

Hypothesis In patients with AV block , LVEF < 50% , NYHA class I , NYHA II

Biventricular pacing would be superior to RV pacing with respect to • combined end point of death • heart failure related urgent care • adverse LV remodeling manifested by a > 15 %

LVESV index

NEJM 2013

Methods • Prospective • Multicenter ( 58 sites in United States & 2 in

Canada ) • Randomized • Double blind

Methods • 918 patients were enrolled from Dec 2003 till Nov

2011• 691 randomized • Follow up average 37 months

Statistical analysis : Bayesian statistical method was used with pre specified metric of benefit being : posterior probability > 0.95

Methods

Eligibility criteria

• Class I / IIa indication for pacing • NYHA I – NYHA III heart failure • LVEF less than 50%

Methods

Exclusion criteria • Previous receipt of CRT • Unstable angina • Acute MI • PCI / CABG in last 30 days • Valvular disease with indication for surgery /

repair

Methods • Implanted pacemaker with or without ICD with

biventricular pacing capability • RV pacing for 30 -60days while OMT was given

• In patients without atrial arrhythmias atrial lead was also implanted for atrial synchronized RV or biventricular pacing

Methods

• Echocardiographic examination was done at baseline then at 6 , 12, 18 and 24 months

Prespecified outcomes: • Packer clinical composite score • QOL• NYHA functional class

Packer composite clinical score

Worsened • Died • Experienced a hospitalization• Worsening of NYHA class Improved Improvement in NYHA class Reduced symptoms Unchanged : none of the above criteria met

Results

Packer composite clinical score

NYHA class at baseline

NYHA functional status

NYHA functional status in Crossovers

QOL

QOL

Discussion

Miracle trial • 453 patients • Moderate to severely symptomatic • LVEF <35%• QRS >130ms

Assessed for NYHA class ; QOL ; 6min walk distance CRT arm versus no CRT with OMT

Miracle trial : results

Significant improvement in • 6 minute walk distance • QOL• Time on treadmill• Ejection fraction • Required fewer hospitalization / iv medications

Miracle trial

Effects similar to those seen with beta blockers in heart failure were seen in this trial but these effects

were seen with CRT who were already on beta blockers

Miracle trial

COMPANION TRIAL

NEJM 2004

COMPANION TRIAL

CARE HF trial

CARE HF trial • 82 European centers • Jan 2001 to march 2003 • non blinded trial • CRT versus OMT

Eligible patients ( 404 to CRT ; 409 to OMT ) • NYHA III –IV on OMT • LVEF <35%• LVEDD at least 30mm • QRS >120ms

Kaplan Meir estimate of primary end

outcome

Kaplan Meir estimate of primary secondary

outcome

REVERSE trial

Reverse Trial • 610 patients • NYHA class I / II • QRS >120ms• LVEF < 40%

Received CRT +/- D

Reverse Trial • Clinical composite score • LV systolic volume index

Results : Significant improvement in LV systolic index Fewer hospitalization

Reverse Trial Conclusion :

CRT reduces the hospitalization in HF patients and improves ventricular structure and function in NYHA class I and II with ventricular dyssynchrony

MADIT CRT trial

MADIT CRT trial

MADIT CRT trial

MADIT CRT trial Conclusion

CRT D versus ICD alone • Reduced heart failure events • Females benefit more than males • QRS >150 benefit more • Patients with LBBB show a significant reduction in

VT /VF and death compared to non LBBB

RAFT trial

RAFT trial

RAFT trial

Updated CRT guidelines

• Limitation of class I indication to QRS >150ms • Limitation of class I indication to LBBB • Expansion of class I indication to NYHA II and with

LBBB with QRS >150ms• Addition of class IIb recommendation who have - LVEF <30% - Ischemic HF - Sinus rhythm - LBBB with QRS > 150 ms - NYHA I