Purpose: The TRAJECTORIES study (Trajectory Changes Of Coronary Sinus Lead Tip And Cardiac Resynchronization Therapy Outcome, NCT02340546) is an observational study by seven Italian centers about the prediction of CRT-induced LV reverse remodeling by means of the acute 3DTJ changes at CRT implant. Preliminary description and results are reported.
Methods: In CRT implants with standard indications, stable CHF and regular ventricular rhythm, a fluoroscopic sequence in two standard X-rays views of a few seconds was acquired immediately before (T-1) and after the start of BIV (T0). 3DTJ at T-1 and T0 were reconstructed using a procedure to track the CS lead cathode pole throughout the cardiac cycle and applying stereo-photogrammetric rules, and the mean 3DTJ over a cardiac cycle was computed. Geometric features and shape of mean 3DTJ were then analyzed. Changes of S1/S2 (?S1/S2) between T-1 and T0 were compared with the volumetric response at six-month f.u: the percent negative variation of S1/S2 (?S1/S2<0), marking a more multi-directional shape of 3DTJ, was assumed to predict the response to CRT. Volumetric response was adjudicated by a core-lab using a cut-off reduction = 15% in echocardiographic LV end-systolic volume at f.u..
Results: Out of 119 patients enrolled in 42 months, 39 pts ended f.u. (28 m; age 69±10) and 10 dropped–out. Fluoroscopies were acquired easily and 3DTJ were fully reconstructed. Patients baseline features were: ischemic heart disease (IHD) 24/39 pts; sinus rhythm 35/39 pts; upgrade from PM/ICD 9/39 pts; QRS morphology with LBBB 30/39, intraventricular aspecific delay 3 and RV pace 6 pts; LV ejection fraction (EF) 32±10%; QRS duration 162±26 ms. At f.u., volumetric R were 26/39 (66%). Concordance between ?S1/S2 (as either ?S1/S2<0 or ?S1/S2>0) and volumetric response was 79% overall (31/39), 92% in R (24/26), 61% in non-R (8/13). Non-concordant patients were older (73±8), predominantly with IHD (6/8) and mostly non-R (5/8), but no differences in QRS and EF were found. The proposed 3DTJ metric showed sensitivity = 82%, specificity =72%; positive predictive value = 88%, negative predictive value = 61%.
Conclusions: Metrics of 3DTJ seem promising to acutely predict CS pacing site-specific response to CRT in long-term, above all in R. 3DTJ might depict aspects of CRT delivery effects on LV mechanics.