Assessment Of Left Ventricular Contraction Patterns Using Gated SPECT MPI To Predict Cardiac Resynchronization Therapy Response

[Background].Cardiac resynchronization therapy(CRT)is an effective treatment for patients with drug-refractory heart failure,but 30%-40%patients after CRT cannot get favorable responses.The U-shaped left-ventricular(LV)contraction pattern,identified by MRI or echocardiography,is associated with improved CRT response.Gated SPECT MPI can measure both myocardial viability and mechanical dyssynchrony in a single scan.This study is aimed to apply gated MPI to identify LV contraction pattern and evaluate its influence to CRT response in patients with left bundle branch block(LBBB).[Methods]Fifty-eight patients who met CRT guidelines,had pre-CRT MPI andreceived CRT,were enrolled.The perfusion with less than 50%of maximum uptake was defined as scar.The LV regional contraction onsets were used to identify contraction patterns.The U-shaped pattern was characterized by a U-shaped sequence of mechanical contraction caused by a block line in the direction of contraction propagation.CRT response was defined as the left ventricular ejection fraction(LVEF)increase at least 5%after 6-month follow-up.[Results]Twenty-eight patients(48.3%)had a U-shaped contraction pattern and thirty patients(51.7%)had a non-U-shaped contraction pattern.The U-shaped group showed a significantly higher response rate than the non-U-shaped group(89.3%vs.56.7%;p=0.005).In univariate and multivariate logistic regression analysis,the U-shaped pattern was independent predictor of CRT response(Univariate:OR:6.37,95%CI:1.57 to 25.80 p =0.009;Multivariate:OR:16.01;95%CI:1.82 to 140.58 p=0.012).[Conclusion]Gated SPECT MPI can identify LV mechanical contraction patterns.The U-shaped contraction pattern is significantly associated with improved CRT response.