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Potential Novel Heart Failure Diagnosis Method for Patients With AFib


Among patients with atrial fibrillation (AFib) in the RATE-AF trial, the index-beat approach produced superior results on a potential diagnosis of heart failure vs consecutive-beat methods.

Among patients with atrial fibrillation (AFib) enrolled in the RATE-AF trial, the index-beat approach produced superior results on a potential diagnosis of heart failure compared with consecutive-beat methods, according to the study published in Heart.

Knowing that approximately half of patients with AFib eventually develop heart failure, and that the current method of evaluating systolic and diastolic function may be unreliable because of R-R intervals that vary, the authors wanted to evaluate a more physiological-based approach of gauging heart failure risk in patients with AFib. The current consecutive-beat methods they evaluated were averaging 3 beats (clinical routine) and 5 and 10 beats (per guidelines).

“We wanted to improve the echocardiographic assessment of heart failure in patients with AFib by comparing conventional averaging of consecutive beats with an index-beat approach, whereby measurements are taken after 2 cycles with similar R-R interval,” they said.

Among their cohort of 160 patients (54% male) whose median (interquartile range [IQR]) age was 75 (69-82) years, the lowest within-beat coefficient of variation for left ventricular ejection fraction (LVEF) was 32% with the index-beat method. In contrast, that for 5 and 10 consecutive beats was 51% and 53%, respectively.

Global longitudinal strain (GLS) and mitral E wave max/average diastolic tissue Doppler velocity (or E/e’) were also lowest under the index-beat method compared with the consecutive-beat methods:

  • GLS: 26% vs 43% (5 beats) vs 42% (10 beats)
  • E/e’: 25% vs 41% (5 and 10 beats)

Intraoperator/interoperator variability, time efficiency, and validity against natriuretic peptides were also assessed, and these results demonstrate that it took less time (P < .001) to perform the index-beat method: 35.4 s (95% CI, 33.1-37.8) to measure E/e’ vs 44.7 s (95% CI, 41.8-47.5) with the 5-beat method and 98.1 s (95% CI, 91.7-104.4) with the 10-beat method.

“Using a single index-beat did not compromise the association of LVEF, GLS, or E/e’ with natriuretic peptide levels,” the authors added. “The index-beat approach also demonstrated higher intraclass correlation coefficient (ICC) values for LVEF, GLS, and E/e’.”

All patients enrolled in the RATE-AF trial had baseline echocardiograms (ECGs), and AFib was confirmed via 12-lead ECG. Individuals were excluded if they had a heart rate below 60 bpm or evidence of second- or third-degree heart block, and images were only excluded when their quality did not permit accurate measurements. Most were White British or Irish (93.1%); few were black African, Caribbean, or Black British (1.9%) or Asian or Asian British (5.01%). Baseline measures encompassed a median (IQR) heart rate of 100 (86-112) bpm, median (IQR) blood pressure of 134/84 (123/76-148/93) mm Hg, and median LVEF, GLS, and E/e’ of 59% (IQR, 52%-64%), –14% (IQR, –12% to –15%), and 9.4 (IQR, 7.8-11.7), respectively.

LVEF, GLS, and E/e’ also had the strongest ICC with the index-beat method:

  • LVEF had an ICC of 0.94 (95% CI, 0.93-0.96) vs 0.71 (95% CI, 0.64-0.77) for 3 consecutive beats, 0.76 (95% CI, 0.71-0.81) for 5 consecutive beats, and 0.74 (95% CI, 0.69-0.79) for 10 consecutive beats.
  • GLS had an ICC of 0.88 (95% CI, 0.85 to 0.91) vs 0.81 (95% CI, 0.76-0.85) for 3 consecutive beats, 0.82 (95% CI, 0.77-0.85) for 5 consecutive beats, and 0.80 (95% CI, 0.75-0.84) for 10 consecutive beats.
  • E/e’ had an ICC of 0.96 (95% CI, 0.95-0.97) vs 0.81 (95% CI, 0.76-0.85) for the average of 3 beats, 0.77 (95% CI, 0.72-0.81) for the average of 5 beats, and 0.78 (95% CI, 0.73-0.81) for the average of 10 beats.

Noting that accurate systolic and diastolic measures are a must-have for patients with AFib, because heart failure is often a common outcome, the authors highlight that strengths of their findings include the “very high levels of variation” their study showed in the 10-consecutive-beat method and that the index-beat method “has a high level of reproducibility between different operators.”

“In a blinded analysis without preselection for image quality, assessing left ventricular function using the index-beat method provides a more reproducible and quicker method of assessing heart function in patients with AFib,” they concluded. “Pending independent validation, our results suggest that echocardiography departments should change to the index-beat method to diagnose and characterize heart failure in patients with AFib.”


Bunting KV, Gill SK, Sitch A, et al; RAte control Therapy Evaluation in permanent Atrial Fibrillation (RATE-AF) trial group. Improving the diagnosis of heart failure in patients with atrial fibrillation. Heart. Published online March 10, 2021. doi:10.1136/heartjnl-2020-318557

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