Trial # Patients Inclusion criteria Randomization arms Follow-up Results
Trial # Patient Inclusion criteria Randomization arms Follow-up  
ADOPT [42] 319 enrolled
288 analyzed
≥2 AF episodes within 1 month prior to implant, sinus node dysfunction DDDR @60bpm with continuous overdrive ON vs. OFF 6 months Reduction in AF burden from 2.5 to 1.87% (p=0.005). No difference in QOL or # AF episodes
Puglisi et al.[43] 149 enrolled
98 analyzed
1 episode AT within 6 months, bradycardia DDD@70bpm closed loop system vs. DDD@70bpm with continuous overdrive vs.
DDDR@70bpm
6 months Decreased AT burden in closed loop system (20.3min/d) vs. overdrive (56min/d) or DDD (63min/d) (p<0.01)
PIRAT[44] 70 enrolled
37 analyzed
Device-documented AT, bradycardia DDDR + all therapies with ERAF suppression ON vs OFF (atrial overdrive, short-long prevention, burst+ATP, ramp ATP active in both phases) 3 months No difference in median number AT episodes, AT burden, % ERAF, symptoms, or QOL
3/4[45] 107 PAF, bradycardia 3 triggered algorithms (PAC suppression, short-long prevention, post-exercise response) vs. 4 (3 triggered + continuous overdrive) 3 months Decreased AF burden in 3 vs. 4 from (5.1 vs. 12.7, p=0.026). Decreased AF episodes in 3 vs. 4 (405 vs. 621, p=0.05).
SAFARI[28] 554 enrolled
187 analyzed
AF, bradycardia All algorithms ON vs. OFF (continuous overdrive, short-long prevention, post-exercise response, PAC suppression, ERAF suppression, VRS) 6 months Decrease in AF burden with algorithms ON (decrease by 0.11h/d vs. increase of 0.01in OFF group). No difference AF frequency, avg sinus duration, hospitalizations, or cardioversions.

Table 1: Trials evaluating pacing algorithms for prevention of AF (bradycardia indication required)

Trial # Patient Inclusion criteria Randomization arms Follow-up Results
PAF-PACE[46] 42 enrolled
35 analyzed
≥2 episodes/month during prior 3 months No pacing vs. medium overdrive vs. high overdrive pacing Variable depending on severity of PAF Medium (p=0.01) and high (p=0.002) overdrive pacing reduced symptomatic AF versus no pacing.
PIPAF[47] 95 enrolled
55 analyzed
≥1 episode AF within 3 months, 49% bradycardia DDDR@70bpm with algorithms ON vs. OFF (atrial overdrive, short-long prevention, PAC suppression) 6 months No difference in AT duration, frequency, or symptoms. Decrease in AT duration with low ventricular pacing (p<0.04) and decrease in AT number with increased atrial pacing (p<0.03).
PAFS[48] 182 enrolled
79 analyzed
≥3 AF episodes within 1 month, AF burden 1-50% Atrial overdrive vs. VRS vs. atrial overdrive + VRS + ERAF suppression vs. OFF (DDR@60bpm) 1 month No difference in AF burden. PAC triggered AF reduced with atrial overdrive.

>Table 2: Trials evaluating pacing algorithms for prevention of AF (bradycardia indication not required)

Figure 1: Heart rate trend over 24 hours that shows a patient with persistent AF. Note that the ventricular rate regularization algorithm is initially turned “on” and the average heart rate is around 90 bpm. Once this algorithm is turned “off”, the average heart rate is in the range of 70 bpm.

Figure 2: Stored histogram of atrial high rate episodes over a period of several months. Initially, AF is recorded by the device as occurring daily for approximately 24 hours per day. This is consistent with the patient history of persistent AF. After AF ablation, no further AF is recorded. This information is potentially useful in patient management.

Figure 3: An example of far field over sensing on the atrial channel of a dual chamber device (arrow points to one example). Far field over sensing may result in false automatic mode switch or atrial high rate episodes. While programming the sensitivity may sometimes eliminate far field sensing, in this example the far field R wave is too large.

Figure 4: A) Pacemaker interrogation reveals multiple episodes of mode switch during a single day. This most likely represents a single episode of AF, with intermittent under sensing of atrial electrograms which results in counting multiple episodes rather than one. B) Atrial electrogram in atrial fibrillation. Note the irregular amplitude of the signals leading to intermittent under detection. This figure illustrates some of the challenges in utilizing the pacemaker to detect the amount of AF the patient is having.