Effect of optimizing the VV interval on left ventricular contractility in cardiac resynchronization therapy

Area of Science:

• Cardiology
• Biomedical Engineering
• Heart Failure Management

Background:

• Simultaneous biventricular pacing is known to improve left ventricular (LV) function in heart failure patients with LV asynchrony.
• The precise timing of the interventricular pacing interval (VV interval) may offer further optimization of LV function.

Purpose of the Study:

• To investigate the acute hemodynamic response to varying the VV interval.
• To assess the impact of VV interval optimization on LV function, using maximum LV dP/dt (LV dP/dt(max)) as the primary parameter.

Main Methods:

• A biventricular pacemaker was implanted in 53 patients with advanced heart failure (NYHA class III-IV), left bundle branch block, LV asynchrony, and QRS interval >150 ms.
• Optimization of atrioventricular and VV intervals was guided by LV dP/dt(max) measurements using a 0.014-in sensor-tipped pressure guidewire.

Main Results:

• Simultaneous biventricular pacing improved LV dP/dt(max) by 17% in ischemic cardiomyopathy, 18% in idiopathic dilated cardiomyopathy, and 21% in atrial fibrillation.
• Optimizing the VV interval yielded further absolute increases in LV dP/dt(max) of 8%, 7%, and 3% in the respective groups.
• Optimal VV intervals varied, with LV pacing first being the most common configuration for achieving maximum dP/dt(max).

Conclusions:

• Optimization of the VV interval significantly enhances LV dP/dt(max) compared to standard simultaneous biventricular pacing.
• The 0.014-in sensor-tipped pressure guidewire provides an easy, accurate, and reliable method for evaluating VV interval optimization.
• Tailoring the VV interval is a crucial step in maximizing hemodynamic benefits in patients receiving biventricular pacing for heart failure.