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Purpose: Left ventricle (LV)-only pacing is non-inferior to biventricular pacing but permanent fusion pacing is needed to ensure cardiac resynchronization therapy (CRT) responsiveness. The role of systematic exercise testing (ET) in these patients has not been established. This study was designed to assess clinical and therapeutic implications (device programming/drugs) of systematic ET in patients requiring fusion-pacing CRT without an right ventricle (RV) lead. Methods: Consecutive patients with a right atrium/LV-only dual-chamber (DDD) pacing system were included. Prospective data were obtained: device interrogation, ET, and echocardiography at every 6-month follow-up visit. CRT assessment during ET included maximal heart rate, beat-to-beat echocardiography analysis of LV fusion pacing, LV loss of capture, and improvement in exercise capacity. If LV loss of capture or unsatisfactory LV fusion pacing occurred, reprogramming was individualized for each patient and ET redone. Results: A total of 55 patients (29 male) aged 62±11 years were included. During follow-up (39±18 months), a total of 235 ETs were performed, with mean exercise load 6.4±1.3 metabolic equivalents of task (118±35 W, maximal heart rate 119±17 beats/min). Twenty patients (36%) had inadequate pacing or loss of LV capture during ET, due to exceeding the maximum tracking rate (11%), chronotropic incompetence (7%), and LV pacing outside the fusion-pacing band (18%), caused by physiological shortening of the PR interval or exagerated LV preexcitation during maximum exercise. Post-ET CRT-device optimization included reprogramming of rate-adaptive atrioventricular interval (total decrease 23±8 ms), individualized programming of maximum tracking rate, or rate-response function. Drug optimization was performed in 32% of patients, and ET redone in 36%. Conclusion: In one of three ETs, an intervention in device and medication optimization was done to ensure a better outcome. Routine ET should be a standard approach to maximize fusion-pacing CRT response during follow-up., Competing Interests: The authors report no conflicts of interest in this work.

Background: Premature ventricular contractions (PVCs) may cause subtle changes in left atrium (LA) structure and function which may not be readily detected by conventional parameters., Aim: To explore the relationship between PVCs and LA shape and size remodelling in patients without known structural heart disease., Methods: PVC frequency per 24 h was divided into tertiles. Echocardiographic measurements included left ventricular ejection fraction (LVEF) and volume, LA volume (LAV), mid-LA transverse diameter (LAt), and basal LA maximal transverse diameter (LAb). Trapezoidal LA shape was defined by LAt less than LAb. The association between PVCs and LA shape was explored by multivariable adjusted logistic regression., Results: The 121 patients had a mean age of 43.1 years (63% male) and mean LVEF of 56%. Mean LAV was 57.7 mL in the lowest PVC tertile, 70.9 mL in the middle, and 87.1 mL in the highest PVC tertile (p < 0.001). Trapezoidal LA shape was documented in 32 patients. Five per cent of patients in the lowest and 65% in the highest PVC tertile had trapezoidal LA shape (p < 0.001). PVC frequency correlated with LAV (r = 0.87, p < 0.001) and LAb (r = 0.56, p < 0.001). Each 10% increase in PVCs was significantly associated with trapezoidal LA shape (OR = 1.32, 95% CI 1.17-1.48), after adjustment for age, sex, mean blood pressure, LVEF, and LV end-diastolic diameter., Conclusions: Frequent PVCs are associated with larger LAV and trapezoidal LA shape in otherwise healthy patients, suggesting LA remodelling in response to increased LV filling pressure.

Purpose: Assessment of volume in relation with left atrial (LA) shape alteration before and after PV isolation., Methods: We compared trapezoidal modification of LA using echocardiography with the ellipsoid formula (EEL: ) and CT, with both ellipsoid (CTEL: ) and truncated cone formulas (CTTR: ), in 40 patients, before and +/-3 months after AF ablation., Results: A trapezoidal shape was present in 76.3% of patients. The different volume measurements were statistically correlated (r = 0.603-0.837, p < 0.001) irrespective of the formula used. After reverse remodeling, with 77.5% of patients in stable sinus rhythm, correlation coefficient for volume remained significant (p < 0.001)., Conclusions: In AF, dilation of the LA is associated with a geometrical trapezoidal change in many cases. The CT truncated cone formula applies best for precise evaluation of trapezoidal shape alteration in dilated AF atria. There is a good correlation between CTTR: and echocardiography which remains a valuable estimation for volume calculation in clinical practice.

Background: The ellipse formula often underestimates left atrial (LA) dilation. Complete echocardiographic analysis of LA shape in relation to electrical remodeling has not been performed., Aim of the Study: To analyze the relation between LA shape/surface and vulnerability to atrial fibrillation (AF)., Methods: We studied 112 patients aged 43 +/- 16 years, and referred for electrophysiological study. LA surface (LAS) was measured at end-systole (maximal). Trapezoidal LA shape was defined if the transverse dimension was less than the basal dimension. Decremental index (DI) was calculated as the maximal percentage prolongation of interatrial conduction time during atrial extrastimulation. The LA was considered vulnerable if AF was inducible. DI > 50%, repetitive atrial activity, and fragmented electrograms defined susceptibility to vulnerability., Results: LAS ranged between 10.5 and 36.6 cm(2); 77 patients had a trapezoidal LA. By simple regression analysis LAS correlated with DI (r(2) = 0.38, P = 0.0001). LAS predicted susceptibility to vulnerability better than vulnerability to AF (area under the ROC curve: 0.93 vs 0.81). The best cut-off value for LAS as predictor of susceptibility to vulnerability was 19.5 cm(2) (sensitivity: 89%; specificity: 90.5%; positive predictive value: 93.4%; negative predictive value: 84.4%). Using LAS > 25 cm(2) as a cut-off value, LA vulnerability to AF was detected with a sensitivity of 56.2% and a specificity of 95% (positive predictive value: 81.8%; negative predictive value: 83.3%). LA shape was trapezoidal in 72% patients with LAS > 25 cm(2) and in 30% patients with LAS < 19.5 cm(2) (P < 0.0001)., Conclusions: LA dilation and electrical remodeling are related. Progressive LA dilation is accompanied by shape remodeling. Appropriate characterization of LA remodeling should therefore include LAS measurement and LA shape assessment.

Unlabelled: Prolongation of the interatrial conduction time (ia-CT) is considered an important factor in the pathophysiology of atrial fibrillation (AF) and as a criterion to perform multisite atrial pacing. Measurement of ia-CT requires an electrophysiologic study. The aim of this study was to compare echocardiographic with electrophysiologic measurements to determine if they are correlated., Methods and Results: The study included 32 consecutive patients who underwent electrophysiologic studies. We measured ia-CT between the high right atrium and the distal coronary sinus. In all patients we measured P wave duration, left atrial diameter and area, and ia-CT by Doppler echocardiography was measured as the difference in time intervals between the QRS onset and the tricuspid A wave, and the QRS onset and the mitral A wave (DT). Ia-CT was statistically correlated with DT (r = 0.79, P < 0.0001), but not with P wave duration or left atrial dimensions., Conclusions: Measurement DT may be reliable to estimate ia-CT without invasive procedure. Accordingly, DT could be used as a simple selection criterion when considering patients for atrial resynchronization therapy.