Device-detected atrial high-rate episodes (AHRE) are associated with more than twice the risk for cardiovascular and all-cause mortality, even in patients without prior atrial fibrillation (AF), atrial flutter (AFL), or atrial tachycardia (AT), new research suggested.
Cardiac implantable electronic devices (CIEDs) with continuous rhythm monitoring, including implantable cardioverter defibrillators (ICDs) and cardiac resynchronization therapy defibrillators (CRT-Ds), enable the detection of often asymptomatic, brief episodes of AT/AF, which are referred to as AHRE or subclinical AF.
"Previous studies have confirmed that patients with AHRE are at a higher risk of clinical AF, heart failure, and thromboembolism events," study author Shu Zhang, MD, PhD, of State Key Laboratory of Cardiovascular Disease, Arrhythmia Center, National Center for Cardiovascular Diseases, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College in Beijing, told Medscape Medical News. "These outcomes could potentially lead to a poor long-term prognosis."
Indeed, the retrospective analysis of patients with CIEDs revealed that after adjustment, patients with AHRE had a significantly higher risk for cardiovascular (hazard ratio [HR], 2.40) and all-cause mortality (HR, 2.31).
The study was published online on December 11 in the Canadian Journal of Cardiology.
Consider Additional Screening
The researchers analyzed archived data from the Safety and Efficacy of Biotronik Home Monitoring System in Cardiac Implantable Electronic Device Patients registry for patients with ICD or CRT-D implantation and no history of AF, AFL, or AT.
The investigators identified 343 patients (mean age, 62.5 years; 77.6% men) with at least 1 day of AHRE lasting ≥ 15 minutes. Overall, 49% had an ICD, and 51% had a CRT-D device. There were no significant differences in baseline characteristics such as age, sex, and comorbidities between those with and without AHRE, except for patients with AHRE who received more diuretics.
The study's primary endpoint was cardiovascular mortality, and the secondary endpoint was all-cause mortality.
During a mean follow-up of 4.2 years, there were 87 (25.4%) deaths, 61 (70.1%) of which were attributed to a cardiovascular cause. Of these deaths, 44 (35.5%) occurred in 124 patients with AHRE. This proportion was significantly higher than in patients without AHRE (43 patients, 19.6%).
A multivariate analysis showed that after adjustment for relevant variables, patients with AHRE had a significantly higher risk for cardiovascular (HR, 2.40) and all-cause mortality (HR, 2.31).
The investigators grouped patients with AHRE on the basis of the longest AHRE duration. The low-burden group had a duration of at least 15 minutes and < 6 hours. The moderate-burden group had at least 6 hours and < 24 hours, and the high-burden group had at least 24 hours.
After accounting for clinically and statistically significant variables, the researchers found that patients in the moderate-burden and high-burden groups had higher risks for cardiovascular (HR, 3.64 and HR, 2.33, respectively) and all-cause mortality (HR, 2.76 and HR, 2.26, respectively) than those in the low-burden group.
In a sensitivity analysis that excluded the 27 patients diagnosed with clinical AF during follow-up, the remaining 97 patients with AHRE still had an elevated risk for cardiovascular (HR, 2.41) and all-cause (HR, 2.98) mortality compared with patients without AHRE.
Because of the elevated risks, "anticoagulation and additional ECG or Holter screening should be considered, based on the patient's AHRE burden and stroke risk factors," said Zhang.
"Combining our study and the recently published ARTESIA study [shows] that patients with AHRE, or subclinical AF, face similar health hazards as those with clinical AF," he added. "In the future, we will strengthen the electrocardiogram and Holter screening of these patients to ensure timely and accurate diagnosis, followed by appropriate treatment."
Unknown Confounders, Variables
Commenting on the study for Medscape Medical News, José Joglar, MD, professor of cardiac electrophysiology at UT Southwestern Medical Center in Dallas and chair of the committee that drafted the 2023 AHA/ACC Guideline for the Diagnosis and Treatment of Atrial Fibrillation, said, "AHRE is a very heterogeneous term. But I would not doubt the findings, since prolonged AHREs are considered a precursor of AF." Joglar did not participate in the current study.
Certain limitations of the study must be considered, however, he said. "This study was observational, so there are a lot of unknown cofounders and variables not accounted for." For example, it's not clear which therapies were given to the patients that might have affected the findings and what other variables may have affected risks.
In terms of future research, he said, "We need to see more nuanced data. What are the underlying conditions or risk factors triggering prolonged AHREs? Are patients being treated and screened properly for those conditions?"
For now, clinicians need to be aware that "prolonged AHREs are a precursor of AF, so patients need to be evaluated and monitored, as well as treated for underlying conditions," Joglar concluded.
This study was supported by the Beijing Municipal Science and Technology Commission. Zhang and Joglar declare no competing interests.
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