Improvements in Clinical outcome with biventricular versus Right ventricular Pacing The Block HF study JACC May 2016 Dr Joura Vishal
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
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
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
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
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 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
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