Validation of diagnostic accuracy of a handheld, smartphone-based rhythm recording device

Figures & data

Table 1. Baseline characteristics (n = 189). AF: atrial fibrillation, BMI: body mass index, CTI: cavotricuspid isthmus ablation, Extended AF-ablation: Including substrate modification, lines and/or complex fractionated atrial electrograms (CFAE), PVI: Pulmonary vein isolation, SD: standard deviation.

Age (mean ± SD)	69.0 ± 11.3
Female n (%)	38.1% (n = 72)
BMI (mean ± SD)	27.1 ± 4.5
Previous ablation procedures n (%) One ablation procedure n (%) Two or more ablation procedures n (%) PVI only n (%) PVI + extended AF-ablation n (%) CTI Atypical flutter	50.8% (n = 96) 25.4% (n = 48) 24.9% (n = 47) 32.8% (n = 62) 11.1% (n = 21) 4.8% (n = 9) 0.5% (n = 1)

Figure 1. The device is connected by Bluetooth to a smartphone. 30-second chest and 30-second thumb registrations are collected. Permission to use approved by Coala Life AB.

Figure 2. Chest-and thumb registrations during sinus rhythm and atrial fibrillation. Permission to use approved by Coala Life AB.

Figure 3. Study flow diagram. AF: atrial fibrillation, AFL/AT: atrial flutter/atrial tachycardia, ATA: atrial tachyarrhythmia, CHM: Coala Heart Monitor.

Table 2. Accuracy values of CHM~TC~

	Manual analysis of CHM-recordings for ATA (95% CI) (n = 198)	Manual analysis of CHM-recordings for ATA (95% CI) (n = 200)*	Manual analysis of CHM-recordings for AF (95% CI) (n = 198)	Manual analysis of CHM-recordings for AF (95% CI) (n = 200)*	Automatic analysis of CHM-recordings for ATA (n = 200)	Automatic analysis of CHM-recordings for AF (n = 200)
Prevalence	45.5%	46.0%	38.4%	39%	46.0%	39%
Sensitivity	98.9% (94.0–100)	96.7% (90.8–99.3)	100% (95.3–100)	97.4% (91.0–99.7)	93.5% (86.3–97.6)	97.4% (91.0–99.7)
Specificity	100% (96.6–100)	100% (96.6–100)	97.5% (93.0–99.5)	97.5% (93.0–99.5)	92.6% (85.9–96.7)	86.1% (78.6–91.7)
Overall accuracy	99.5% (97.2–100)	98.5% (95.7–99.8)	98.5% (95.6–99.7)	97.5% (94.3–99.2)	93.0% (88.5–96.1)	90.5% (85.6–94.2)
PPV	100%	100%	96.2% (89.3–99.2)	96.2% (89.3–99.2)	91.5% (83.9–96.3)	81.7% (72.4–89.0)
NPV	99.1% (95.0–100)	97.3% (92.3–99.4)	100% (96.9–100)	98.3% (94.2–99.8)	94.3% (88.1–97.9)	98.9% (93.4–99.8)
LR+	∞	∞	40.67 (13.3–124.3)	39.62 (13.0–121.2)	12.6 (6.5–24.6)	6.99 (4.5–10)
LR-	0.01 (0.00–0.08)	0.03 (0.00–0.08)	0	0.03 (0.01–0.10)	0.07 (0.03–0.15)	0.03 (0.01–0.12)
Interrater agreement (κ coefficient)	0.98 (0.95–1.0)	0.98 (0.95–1.0)	0.94 (0.89–0.99)	0.94 (0.89–0.99)

AF: atrial fibrillation, AFL/AT: atrial flutter/atrial tachycardia, ATA: atrial tachyarrhythmia, CHM: Coala Heart Monitor,

CI: confidence interval, LR-: negative likelihood ratio, LR+: positive likelihood ratio, NPV: negative predicitve value,

PPV: positive predictive value.

*Including two non-interpretable CHM-recordings.