High-degree atrioventricular block during anti-arrhythmic drug treatment: use of a pacemaker with a bradycardia-detection algorithm to study the time course after drug withdrawal.

AIM: This study examines the recurrence of high-degree atrioventricular block (AVB) during a follow-up period of 2 years in patients with restored AV node function after antiarrhythmic drug withdrawal at implantation of a pacemaker. METHODS: Nine men and eight women (77 +/- 7 years) taking antiarrhythmic drugs (beta-receptor blockers in 15) and presenting with high-degree AVB were followed for 2 years after being taken off drugs upon receiving a permanent pacemaker with special bradycardia detection software. RESULTS: At inclusion, surface ECG identified two subsets of patients: a QRS duration < 120 ms (n = 5) and those with a QRS duration > or =120 ms (n = 12). During the 2-year follow-up, progression to high-degree AVB occurred in these groups: 1/5 (20%) and 9/12 (75%) P < 0.05. Six patients had to be restarted on drugs, mostly beta-receptor blockers, due to atrial tachyarrhythmias: 3/5 and 3/12. In total, 16 patients (94%) either developed high-degree AVB needing pacing or atrial tachyarrhythmias requiring drug treatment. CONCLUSION: Patients on beta-receptor blocking drugs and QRS width > or =120 ms developing high-degree AVB should be recommended a pacemaker without further investigation or observation.

Assessment of atrial regional and global electromechanical function by tissue velocity echocardiography: a feasibility study on healthy individuals.

BACKGROUND: The appropriate evaluation of atrial electrical function is only possible by means of invasive electrophysiology techniques, which are expensive and therefore not suitable for widespread use. Mechanical atrial function is mainly determined from atrial volumes and volume-derived indices that are load-dependent, time-consuming and difficult to reproduce because they are observer-dependent. AIMS: To assess the feasibility of tissue velocity echocardiography (TVE) to evaluate atrial electromechanical function in young, healthy volunteers. SUBJECTS AND METHODS: We studied 37 healthy individuals: 28 men and nine women with a mean age of 29 years (range 20-47). Standard two-dimensional (2-D) and Doppler echocardiograms with superimposed TVE images were performed. Standard echocardiographic images were digitized during three consecutive cardiac cycles in cine-loop format for off-line analysis. Several indices of regional atrial electrical and mechanical function were derived from both 2-D and TVE modalities. RESULTS: Some TVE-derived variables indirectly reflected the atrial electrical activation that follows the known activation process as revealed by invasive electrophysiology. Regionally, the atrium shows an upward movement of its walls at the region near the atrio-ventricular ring with a reduction of this movement towards the upper levels of the atrial walls. The atrial mechanical function as assessed by several TVE-derived indices was quite similar in all left atrium (LA) walls. However, all such indices were higher in the right (RA) than the LA. There were no correlations between the 2-D- and TVE-derived variables expressing atrial mechanical function. Values of measurement error and repeatability were good for atrial mechanical function, but only acceptable for atrial electrical function. CONCLUSION: TVE may provide a simple, easy to obtain, reproducible, repeatable and potentially clinically useful tool for quantifying atrial electromechanical function.

Clopidogrel and warfarin: absence of interaction in patients receiving long-term anticoagulant therapy for non-valvular atrial fibrillation.

The effect of concomitantly administered clopidogrel on anti-coagulation status was investigated in patients receiving long-term warfarin therapy. Forty-three patients with non-valvular atrial fibrillation who were receiving long-term warfarin and had a stable international normalized ratio (INR) between 2 and 3 were randomly assigned to clopidogrel 75 mg daily or placebo for 8 days (Days 1-8). INR (primary endpoint) and plasma levels of warfarin enantiomers (secondary endpoint) were evaluated at Days 3, 6, 9, 13 and 22. Mean INR remained extremely stable in the clopidogrel group, the maximum percentage change from baseline being 0.6% at Day 6. Plasma levels of R- and S-warfarin also remained very stable in those receiving clopidogrel. No serious adverse events, premature discontinuations of study drug or bleeding occurred with clopidogrel. In conclusion, the stable anticoagulation status of patients receiving long-term warfarin therapy is unaffected by concomitant administration of clopidogrel 75 mg daily.