LAUSR

Objective: To assess the diagnostic accuracy of a novel oscillometric 24-hour ambulatory blood pressure (ABP) monitor (Microlife WatchBP O3 Afib) with implemented algorithm for automated atrial fibrillation (AF) detection during each ABP measurement in elderly hypertensives. Design and method: Elderly subjects (age > 64 years, or 50–64 years, untreated or treated for hypertension, with stroke history or suspected arrhythmias) were subjected to simultaneous 24-hour ABP monitoring and 24-hour electrocardiography (ECG). Results: One hundred subjects (mean age 70.6 ± 8.2 [SD] years, men 53%, hypertensives 85%, 17 with permanent AF, 4 paroxysmal AF, 79 non-AF) were analyzed. Among a total of 6,410 valid ABP readings, 1,091 (17%) were taken in ECG AF rhythm. In reading-to-reading ABP analysis, the sensitivity, specificity and accuracy of the ABP monitor in detecting AF was 93%, 87% and 88% respectively. In non-AF subjects, 12.8% of the 24-hour ABP readings indicated false positive AF, of whom 27% were taken during supraventricular premature beats. There was a strong association between the proportion of false positive AF readings and that of supraventricular premature beats (r = 0.67, p < 0.001). In paroxysmal AF and non-AF subjects, the receiver operating characteristics curve (area under the curve 0.83, p < 0.01) showed that positive AF readings at 15% during 24-hour ABP monitoring had 90% sensitivity and 77% specificity for detecting AF (episode of any duration in 24-hour ECG). Conclusions: A novel 24-hour ABP monitor with AF detecting algorithm has high sensitivity and moderate specificity for AF screening during routine ABP monitoring in elderly hypertensives. AF detected in 15% or more of the 24-hour ABP readings in elderly hypertensives should mandate 24-hour ECG monitoring for suspected AF.