Resynchronization Pacing for Heart Failure in Congenital Heart: Evaluating Noninvasive Studies to Define Clinical Improvement

Abstract

Background: Information on congenital heart disease (CHD) patients (pts) with heart failure (HF) following cardiac resynchronization therapy (CRT), is limited and currently recommended non-invasive (QRS, ejection fraction [EF]) parameters to monitor clinical improvement are often unreliable due to CHD anatomy, surgical repairs and preexisting pacemakers (PM). Objective: This is a review of young CHD pts with CRT/HF to determine if more updated (including strain) non-invasive studies offer improved correlation with clinical improvement. Methods: Sixteen CHD pts (mean age 17.4{±}5.2y) with CRT success confirmed by direct contractility indices [dP/dt-max]) and clinical findings, had non-invasive (ECG, ECHO) pre- and 1 year post-CRT comparisons. ECHO studies included newer global longitudinal strain (GLS), left atrial strain (LAS), sphericity indices, as well as standard measurements. Results: After 1 year following CRT, pts persisted with improved (I-II) NYHA status. Contractility (dP/dt) remained improved from pre-CRT values (908{±}295 vs 550{±}176mmHg-sec [p=0.002]). QRS duration shortened but only among pts with pre-existing PM (160{±}26 vs 127{±}20ms [p=0.02]). Standard measured ECHO parameters, including EF, showed only non-significant changes. However, endocardial GLS ([-6.4{±}2.9 vs. -9.4{±}4.8%] p =0.04) and contraction phase LAS ([-5.8{±}4 vs- 9.3{±}%] p=0.02) were significantly improved. Conclusion: CHD pts are a distinct group without established Guidelines to non-invasively follow clinical CRT/HF improvement. This first study of newer ECHO-derived measurements among CHD/CRT pts indicates that GLS and LAS have potentially greater correlation with clinical improvement than either EF or QRS duration and may offer better analysis of CRT efficacy.