HRS Feature: Higher ablation volume = better outcomes, especially for VT

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DENVER—Both mortality and complication rates of catheter-based ablations for arrhythmia appear to decrease as total procedure volume at a given center increases, according to poster study presented here Wednesday at the 31st annual scientific sessions of the Heart Rhythm Society. Lead author Russell Heath, MD, told Cardiovascular Business News that their data is “suggestive” that these procedures should only be performed in centers of excellence.

With many invasive procedures, there is a correlation between the quantity performed and the complication and mortality rates. However, the study authors wrote that it is “unclear” whether hospital volume of catheter ablation of cardiac arrhythmias is associated with complications or mortality.

Heath, a cardiology fellow at the University of Colorado in Denver, and colleagues obtained public discharge for the years 2000-2006 from the California Office of Statewide Health Planning and Development, which documents every admission to an acute-care facility in the state. Using ICD-9 codes, they identified admissions, including catheter ablation in cardiac tissue; and quantified complications and mortality using these codes where the diagnosis was present on admission and the ablation was performed.

The researchers assessed data on 26,389 cardiac ablations. Heath acknowledged they are aware of individual operator volume, but with its limitations, administrative data allow investigators access to a great deal of patient information.

They reported that in-hospital mortality was 0.61 percent and major complications occurred in 4.5 percent. These both decreased as procedure volume increased, according to the authors. Mortality by hospital volume was: 0-10: 1.68 percent; 10-50: 0.90 percent; and more than 50 percent: 0.59 percent.

Heath noted that the “straightforward data” with ventricular tachycardia (VT) ablations are likely to be statistically significant. However, “with atrial fibrillation [AF] ablations, the data are much less clean because AF is just a diagnosis, so patients who come in for other types of ablations may get lumped into that group.” As a result, fewer conclusions can be drawn from the AF ablation data, whereas with the VT ablations, Health said he could “cautiously" conclude that volume is consistently equated with better outcomes.

Regardless, Heath and colleagues concluded that there “appears to be a threshold of total procedures beyond which both the mortality and complication rates reach a steady state.”

For a volume threshold, Heath said it varies across the type of ablation performed, which “tracks well according to the complexity of the procedure.” For example, VT ablation requires a higher number of procedures to reach the threshold, compared with the other types of ablation procedures. While 500 procedures per facility seems to be the best uniform threshold, if it is broken down to specific ablative types, it “varies quite a bit,” Heath said.