Clinical and gated SPECT MPI parameters associated with super-response to cardiac resynchronization therapy

Area of Science:

• Cardiology
• Medical Imaging
• Biomedical Engineering

Background:

• Cardiac resynchronization therapy (CRT) is a key treatment for heart failure.
• Super-response to CRT, defined by significant improvements in left ventricular ejection fraction (LVEF) and New York Heart Association (NYHA) class, is associated with better outcomes.
• Assessing cardiac mechanical synchrony using phase standard deviation (PSD) from gated myocardial perfusion imaging single-photon emission computed tomography (gSPECT) may help identify super-responders.

Purpose of the Study:

• To evaluate cardiac mechanical synchrony (PSD) in super-responders after CRT.
• To identify clinical and imaging characteristics associated with super-response to CRT.

Main Methods:

• 158 patients underwent gSPECT before and 6 months after CRT.
• Super-responders (SR) were defined as those with LVEF improvement > 15% or LV end-systolic volume reduction > 30%, with NYHA class I/II.
• Regression analysis was used to identify predictors of super-response.

Main Results:

• 22% of patients (34/158) were classified as super-responders.
• Super-responders had significantly lower PSD at 6 months post-CRT (32° ± 17°) compared to responders (45° ± 24°) and non-responders (46° ± 28°) (P = .02).
• Independent predictors of super-response included absence of prior coronary artery disease (CAD) (OR 18.7), absence of diabetes mellitus (OR 13), and history of hypertension (OR 0.2).

Conclusions:

• Improved LV dyssynchrony post-CRT, not at baseline, is a hallmark of super-responders.
• Absence of diabetes and CAD, and a history of hypertension, are independently associated with super-response to CRT.