Short Bouts of Atrial Tachyarrhythmia Do Not Worsen Prognosis, Study Suggests

Perhaps providing some clarity to a vexing clinical scenario, a registry study shows that patients with only brief episodes of atrial tachycardia/atrial fibrillation (AT/AF) detected by implanted cardiac devices do not have higher rates of adverse outcomes compared with patients with no such occurrences.

The results “allow one to not overreact to brief episodes of atrial fibrillation . . . and anticoagulate patients who are likely to have more risk from anticoagulation than benefit,” lead author Steven Swiryn, MD (Northwestern University, Chicago, IL), told TCTMD.

Even so, he added, many patients initially presenting with only short episodes will eventually develop prolonged bouts, which were associated in this and prior studies with an elevated risk of adverse outcomes over time. That highlights the importance for careful and regular follow-up among those with brief AT/AF episodes, he said.

Commenting on the study for TCTMD, Ayman Hussein, MD (Cleveland Clinic, OH), said that “brief” probably meant that the episodes lasted about 15 to 20 seconds and that such events would not necessarily trigger any additional intervention in his practice.

More important than the duration of any AT/AF episodes is the overall risk profile of an individual patient, Hussein said, adding that if enough risk factors for stroke are present, he’ll anticoagulate even if only short episodes have been recorded.

That said, interpretation of the study findings is limited by the observational design and by the fact that the analysis looked at overall device populations without identifying specific high-risk subgroups, according to Hussein.

Thus, the study “provides significant information about the natural history of this type of rhythm abnormality and its implication but may not necessarily change clinical practice at this stage,” he said.

Prolonged Episodes Signal Increased Risk

The best way to respond to short-lived AT/AF detected by implanted devices is a common dilemma for clinicians, Swiryn said, and one that is not well addressed in practice guidelines.

In the current study, published in the October 18, 2016, issue of Circulation, investigators explored the potential impact of such brief episodes with data from the prospective RATE Registry. The analysis included 5,379 patients with a St. Jude Medical pacemaker or implantable cardioverter-defibrillator (ICD) enrolled at 225 US sites between 2006 and 2012. Median follow-up was 22.9 months.

Looking at electrograms, the researchers defined long episodes of AT/AF as those in which the onset and offset of the episode were not contained within a single recording. Short episodes were those in which the onset and offset were present within a single recording.

Overall, 50% of patients had at least one AT/AF episode of any duration. Only short episodes were found in 9% of patients with a pacemaker and 16% of those with an ICD.

After multivariable adjustment, long AT/AF episodes were not associated with any clinical events in patients with a pacemaker. That contrasts with the findings from the ICD population, in which long episodes were related to higher risks of composite adverse outcomes (OR 1.57; P = 0.006), hospitalization for clinical AT/AF (OR 5.35; P = 0.0001), and all-cause mortality (OR 2.00; P = 0.006).

In an analysis combining the pacemaker and ICD populations, long bouts of AT/AF were associated with incident clinical events (HR 1.68; 95% CI 1.49-1.88), including incident stroke/TIA (HR 1.51; 95% CI 1.03-2.21).

Short episodes, however, were not associated with clinical outcomes in any analysis.

Careful Monitoring Needed

Many patients who at first had only brief episodes of AT/AF went on to develop prolonged bouts, including 55% and 45% of patients with a pacemaker or ICD, respectively.

That’s something that clinicians need to watch out for when their patients with devices return to the clinic for evaluation, Swiryn said. Although some devices can be interrogated remotely, older devices still require patients to come in for face-to-face visits, he noted.

There are no data to inform how frequently those patients should be seen, but it might be worth checking in with a patient with a brief episode of AT/AF every few months, Swiryn suggested.

Hussein, on the other hand, said that he would not necessarily increase the frequency with which patients come in for a device check based on the detection of a short AT/AF episode. In his practice, patients are seen every 3 to 6 months. “We’ll just continue routine follow-up and the anticoagulation decision is totally independent of whether this event was very short or very long,” he said.