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 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.