Ablation the Big Winner in the CABANA Study

By far the major newsmaker at the conference was the announcement of the results from the highly anticipated CABANA (Catheter Ablation vs. Antiarrhythmic Drug Therapy for Atrial Fibrillation) clinical trial with more than 2,200 randomized patients. Although it did not prove that catheter ablation was superior to medical management for a combined endpoint of all-cause death, stroke, serious bleeding, or cardiac arrest, most news stories drew conclusions similar to this BiogWorld analysis:

“The study was close enough to a home run to suggest more widespread use of this technology, a proposal undergirded by patients’ unwillingness to deal with the side effects of antiarrhythmic drugs and a significant improvement in patient quality of life.”

Some key findings and observations highlighted in the articles included:

• The “treatment received” and per protocol analysis drew the most attention from electrophysiologists because in both, ablation demonstrated a significant advantage over drug therapy for the primary composite outcome. The “treatment received” analysis also showed reductions in all-cause mortality and a composite of death or cardiovascular hospitalization with ablation.
• According to Cardiology News, “the results seemed to establish first-line catheter ablation as at least a viable alternative to upfront antiarrhythmic drug management that some patients might find attractive, especially because the results also confirmed ablation as superior to medical treatment as a more definitive treatment of atrial fibrillation (AF) by cutting the rate of recurrent arrhythmia nearly in half.”
• The trial showed that ablation was safe with risks seemingly lower than previously thought and its results would likely accelerate the 15% year-over-year increase in ablations seen in the US in recent years.

AF Patients with Carotid Artery Disease at Increased Risk for Dementia

New research from the Intermountain Medical Center Heart Institute presented at HRS showed that AF patients who also have carotid artery disease are at a significantly higher risk for developing dementia. Both diseases have an adverse effect on blood flow to the brain, which can contribute to the onset of dementia or a decrease in cognitive function.

The data reinforces the continuing need for physicians to monitor and screen patients for both carotid artery disease and AF, especially those at higher risk. Both have similar risk factors, which include age, weight, hypertension, high cholesterol, smoking and diabetes.

New Integrated Risk Score Model More Accurately Predicts Stroke Risk in AF Patients

A composite stroke decision tool that combines the widely used CHA2DS2-VASc with the Intermountain Risk Scores (IMRS) was nearly twice as effective in predicting stroke risk in AF patients compared to using only the traditional CHA2DS2-VASc risk tool.

According to Benjamin Horne, PhD, the lead author of the study, and director of cardiovascular and genetic epidemiology of the Intermountain Medical Center Heart Institute, “the improved effectiveness of the new risk score model can be attributed to better assignment of low-risk and high-risk people to the appropriate stroke prognosis category.”

For example, the traditional CHA2DS2-VASc score places about 80% of women and 50% of men with atrial fibrillation in a group of people at high risk of stroke. In comparison, the IMRS-VASc model places 33% of all people in each of three categories — low, moderate and high-risk.

The study also found that IMRS-VASc more appropriately assigns people to the risk group that relates to their actual prognosis; a lower rate of stroke occurred in the low-risk group and a higher rate in the high-risk category. More accurate assessments of a patient’s risk can help clinicians make better decisions about which patients should have oral anticoagulants or other types of medications and diagnostics tests, and which need to have more frequent clinic visits.

30-second Threshold for Defining an AF Episode May Not Reflect Disease Burden

Although an episode of atrial fibrillation is defined as a fibrillation event lasting at least 30 seconds, a new analysis of monitoring data from 615 patients showed that applying this standard threshold can lead to many patients being diagnosed with AF even though their disease burden may be extremely low.

“A more clinically relevant definition of AF might be a patient with at least one episode that persists for at least 3.8 hours, because this threshold identified people with a median AF burden of just under 10%, “ said Jonathan S. Steinberg, MD, in presenting a poster on the study at HRS. “We’re concerned that the current standard of 30 seconds is way too sensitive.”

ECG Monitoring Detects Paroxysmal AFib More Effectively Than Holter, Patch Methods

Paroxysmal atrial fibrillation (PAF) can be difficult to detect because of its episodic nature. But the results from another large-scale study presented at HRS demonstrates that shortening or extending monitoring duration based on streaming results transmitted by an online ECG monitoring technology improves diagnostic yield compared to fixed offline methods.

The study analyzed 16,595 cardiac telemetry reports developed through use of the PocketECG online monitoring system, a leading arrhythmia monitoring system that transmits full disclosure ECG signal for up to 30 days. It evaluated the impact of monitoring duration on diagnostic yield (DY) in patients with PAF (for AFB ≤ 1% and AFB ≤ 10%) and analyzed the difference in DY between the online method (up to 30 days) and simulated offline methods (24 and 48 hours Holter and multiday patch).

The investigators found that:

For AF burden ≤ 1 %, online monitoring with PocketECG showed:

• DY 6 times higher than the first 24h of Holter monitoring
• DY 3.5 times higher than the first 48h of Holter monitoring
• DY higher by 36 % than the first 11 days with the offline patch
• DY higher by 14 % than the first 18 days with the offline patch

For AF burden ≤ 10 %, the online method showed:

• DY 4 times higher than the first 24h of Holter monitoring
• DY 2.5 times higher than the first 48h of Holter monitoring
• DY higher by 25 % than the first 11 days with the offline patch
• DY higher by 10 % than the first 18 days with the offline patch

For a research summary and abstract of the PocketECG study, click here.