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Ablation and pacing for atrial fibrillation

 

Clinical bottom line

Studies of predominantly non-randomised, non-controlled studies with 1181 patients in 21 reports show that the calculated one year total and sudden death mortality after ablation and pacing therapy was 6.3% and 2.0% respectively.


Reference

MA Wood et al. Clinical outcomes after ablation and pacing therapy for atrial fibrillation. A meta-analysis. Circulation 2000 101: 1138-1144.

Review

The review sought published outcomes studies of radiofrequency ablation and pacing therapy through to June 1998 using MEDLINE, reference lists, and manual searches. Only English language papers were used.

Inclusion criteria were publication in peer-reviewed journal, use of radiofrequency catheter ablation to produce complete heart block in medically refractory atrial tachycardia, or explicit separation of radiofrequency ablation data from direct catheter ablation, and explicit data on sudden death and total mortality.

Results

There were 21 studies, two of which only were randomised trials. Mortality information was available from 16 studies with 1073 patients.

The size of studies varied from 10 to 235 patients, and duration of follow up from seven weeks to 2.3 years (though predominantly longer than six months). The calculated one year total and sudden death mortality after ablation and pacing therapy was 6.3% (95% CI 5.5% to 7.2%) and 2.0% (1.5% to 2.6%) respectively. Mortality was zero for both randomised trials, both with six month follow ups and with 30 and 43 patients with radiofrequency ablation.

There were wide variations. The range of total mortality for one year was 0% to 23%. The range of sudden death was 0% to 9%.

Comment

What are we to think?

On the negative side is that these are predominantly case series, are therefore uncontrolled, and many of limited size (only four had 100 patients or more). We know that non-randomised studies can over-estimate the effects of treatment. Nor are we happy about the exclusion of studies not published in English, even though the authors tell us that they are in broad agreement (which begs the question that if they know that much, why not include them?). Hawkeyed readers of the paper will also spot that the study was supported by the company that makes the equipment.

On the positive side is that this technique is carried out in patients with medically refractory atrial tachycardia, and that, as best we can judge, the patients were not dissimilar (the mean age was mostly in the mid-60s, for instance). We also know that new techniques are often tried first on patients with complicated disease, and for which we may have little else to offer. Knowing the average mortality helps, and it also helps to know that there were wide variations, though the causes were not clear from this paper. In any event, we know what others have achieved, so we have a target against which to measure any service we might use.

There is also an analysis of other measures of clinical outcome, like exercise duration, cardiac function, quality of life, symptoms and healthcare use, all of which show benefit (presumably over pre-treatment, though this is not explicit). So there were fewer outpatient visits, hospital admissions and use of cardiac drugs.

Perhaps the best way of thinking about this is to say that it is a useful start, from which better things can come.