Ablation versus anti-arrhythmic therapy for reducing all hospital episodes from recurrent atrial fibrillation: a prospective, randomized, multi-centre, open label trial.

AIMS: There is rising healthcare utilization related to the increasing incidence and prevalence of atrial fibrillation (AF) worldwide. Simplifying therapy and reducing hospital episodes would be a valuable development. The efficacy of a streamlined AF ablation approach was compared to drug therapy and a conventional catheter ablation technique for symptom control in paroxysmal AF. METHODS AND RESULTS: We recruited 321 patients with symptomatic paroxysmal AF to a prospective randomized, multi-centre, open label trial at 13 UK hospitals. Patients were randomized 1:1:1 to cryo-balloon ablation without electrical mapping with patients discharged same day [Ablation Versus Anti-arrhythmic Therapy for Reducing All Hospital Episodes from Recurrent (AVATAR) protocol]; optimization of drug therapy; or cryo-balloon ablation with confirmation of pulmonary vein isolation and overnight hospitalization. The primary endpoint was time to any hospital episode related to treatment for atrial arrhythmia. Secondary endpoints included complications of treatment and quality-of-life measures. The hazard ratio (HR) for a primary endpoint event occurring when comparing AVATAR protocol arm to drug therapy was 0.156 (95% CI, 0.097-0.250; P < 0.0001 by Cox regression). Twenty-three patients (21%) recorded an endpoint event in the AVATAR arm compared to 76 patients (74%) within the drug therapy arm. Comparing AVATAR and conventional ablation arms resulted in a non-significant HR of 1.173 (95% CI, 0.639-2.154; P = 0.61 by Cox regression) with 23 patients (21%) and 19 patients (18%), respectively, recording primary endpoint events (P = 0.61 by log-rank test). CONCLUSION: The AVATAR protocol was superior to drug therapy for avoiding hospital episodes related to AF treatment, but conventional cryoablation was not superior to the AVATAR protocol. This could have wide-ranging implications on how demand for AF symptom control is met. TRIAL REGISTRATION: Clinical Trials Registration: NCT02459574.

Hemodynamic assessment of mitral mechanical prostheses under high flow conditions: comparison between dynamic exercise and dobutamine stress.

BACKGROUND AND AIM OF THE STUDY: The study aim was to compare the effects of dobutamine stress and exercise on prosthetic mitral valve hemodynamics. METHODS: Twenty-three patients who had recently (3 +/- 1 months) undergone mechanical mitral valve implantation were studied. Hemodynamic variables, two-dimensional echocardiographic and Doppler mitral/aortic flows were recorded at rest, and then repeated during exercise and dobutamine stress. The investigations were randomized place to determine which stress would be performed first. RESULTS: Heart rates and pressure drops rose significantly from resting values. At maximum stress, exercise produced maximum and mean pressure drops which were statistically greater than with dobutamine (19.4 +/- 6.0 versus 12.8 +/- 4.7 mmHg (p < 0.001) and 10.2 +/- 3.5 versus 6.8 +/- 2.8 (p < 0.01), respectively). Exercise was associated with statistically shorter diastolic filling times and higher transvalvular diastolic flow rates. Dobutamine produced a greater augmentation in mitral effective orifice area (EOA) (p < 0.05). The slopes of pressure drop/cardiac flow were calculated for stress type and shown to be significantly lower during dobutamine administration (p = 0.03). CONCLUSION: Normally functioning mitral prostheses can generate significant increases in valvular pressure drops under high flow conditions. Physiological differences exist between dobutamine stress and exercise when assessing diastolic filling. At a given flow rate, dobutamine produces a greater augmentation in the mitral EOA and a smaller drop in transvalvular pressure.

Hemodynamic performance of the Ultracor and Carpentier-Edwards aortic prostheses using exercise and dobutamine stress echocardiography.

BACKGROUND AND AIM OF THE STUDY: The study aim was to compare the hemodynamic profiles of the aortic standard porcine Carpentier-Edwards (C-E) and Ultracor (tilting-disc) valve using exercise and dobutamine stress. METHODS: A total of 36 patients was examined, 18 for each valve type. When analyzing the data, valve types were matched for valve size, which ranged from 21 to 25 mm. All patients were analyzed within an 18-month period after implantation. Hemodynamic variables, two-dimensional echocardiography and Doppler flows were recorded at rest. These were repeated during bicycle ergometry, performed for a maximum of four, 3-min stages, with each stage increasing in workload by 20 W. After resting, patients were subjected to dobutamine stress, administered up to a maximum 40 microg/kg/min, dependent upon heart rate. RESULTS: Mean (+/- SD) resting pressure drops across the C-E and Ultracor valves were comparable (maximum drop 19.4 +/- 8.6 versus 22.9 +/- 12.2 mmHg; mean drop 9.96 +/- 3.8 versus 11.83 +/- 6.6 mmHg, respectively). During exercise, the maximum cardiac flow rate attained was approximately 400 ml/s for both valve types. At this flow rate, the maximum and mean pressure differences between valve types were 6.2 mmHg and 4.4 mmHg, respectively (p = NS). During dobutamine stress, the maximum cardiac flow attained was approximately 500 ml/s, which resulted in significant differences between valve types of 11.6 and 7.3 mmHg, for maximum and mean pressure drops, respectively. When slopes of the mean pressure drop/cardiac flow were calculated for individual valves, a difference was observed between the two valve types (p = 0.02 and p = 0.039 for dobutamine and exercise, respectively). CONCLUSION: Both prostheses demonstrated significant increases in pressure drop under stress conditions. The standard porcine C-E valve had a statistically better hemodynamic profile than the Ultracor prosthesis at higher flow rates. When a study cohort of patients is small, these differences will only be evident at optimal flow rates. The higher flow rates seem most easily obtained when using pharmacological stress.