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Markers of Atrial Myopathy in the General Population
Quick Takes
- Atrial myopathy is an emerging concept that has been linked to risk of AF and AF consequences such as stroke and heart failure.
- An analysis of the SCRAPIS study of general population individuals shows that atrial myopathy markers are very common, but they do not overlap, and that they are correlated with different clinical characteristics.
Study Questions:
What are the prevalence, clinical correlates, and overlap between potential atrial myopathy markers?
Methods:
The authors used the SCAPIS (Swedish CArdioPulmonary biolmage Study) database. The SCAPIS database included 6,013 AF-free subjects who had 24-hour Holters. Resting electrocardiograms (ECGs) measuring P-wave indices were collected on 1,201 subjects, and a random sample of 385 individuals had echocardiographic left atrial volume index (LAVi). The authors postulated the following atrial myopathy markers: 1) ≥500 premature atrial complexes (PACs)/24 hours, 2) LAVi ≥34 ml/m2, 3) P-wave duration >120 ms, or 4) P-wave terminal force in V1 >4000 ms·s. Analyzed clinical correlates included age, sex, body mass index (BMI), height, smoking, physical activity, coronary artery disease (CAD), diabetes, systolic blood pressure (SBP), antihypertensive medication, and low education.
Results:
Within the cohort, 42% of the sample with all diagnostic modalities available had ≥1 atrial myopathy marker, but only 9% had 2 and 0.3% had ≥3. Only P-wave duration and LAVi were correlated (ρ = 0.10, p = 0.04). Clinical correlates of PACs, P-wave indices, and LAVi differed; current smoking, SBP, diabetes, and CAD were associated with PACs. Physical activity ≥2 hours/week was associated with increased LAVi and BMI was associated with P-wave duration.
Conclusions:
The authors conclude that in the general population, indirect markers of atrial myopathy are common but only weakly correlated, and their risk factor patterns are different.
Perspective:
Despite the “statis of blood” hypothesis explaining the notion of thrombus formation in patients with AF, the pathogenesis of an AF-related stroke is much more complex. Studies of patients with implantable loop monitors and with pacemakers and defibrillators have shown lack of temporal association between distinct episodes of AF and strokes. The acknowledgment of this fact is reflected in the most recent 2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of AF (published Nov. 30, 2023), which highlights the preclinical stages and emphasizes the upstream opportunity to alter the natural history of patients at risk for AF.
Atrial myopathy has been increasingly recognized as a key precursor of AF. Atrial myopathy has not been well defined, but several diagnostic criteria have been proposed to be an indicator of the substrate-associated risks: frequent PACs, terminal forces of the P-wave in lead V1, LA enlargement, P-wave duration, intra-atrial block, and abnormal P-wave axis. The current study shows that two fifths of the general population in Sweden has ≥1 of the indirect markers of atrial myopathy. The overlap between the markers, however, was very low and <1% of the general population had an indirect marker of atrial myopathy with all three domains: 24-hour Holter, resting ECG, and echocardiogram.
Further research is needed to establish how to identify individuals with atrial myopathy and how the markers may predict the risk of incident AF, heart failure, and stroke. Individuals with atrial myopathy, if they can be identified, could potentially be an important target group for preventive actions to reduce AF and stroke risk.
Clinical Topics: Arrhythmias and Clinical EP, Atrial Fibrillation/Supraventricular Arrhythmias
Keywords: Atrial Fibrillation, Electrocardiography
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