Subjects with a complication related to the MRI scan. All adverse events in the time frame were recorded at the subject's center and assessed by a centralized Adverse Event Advisory Committee. The committee determined whether each adverse event was a complication (requiring invasive intervention), and whether the event was related to the MRI scan.

Subjects who underwent an MRI scan following study protocol-specified instructions are included. Of the 243 subjects who completed a one-month post-MRI (4-month) visit, 32 did not complete the MRI scan according to the protocol instructions, and are not included.

Subjects' atrial pacing capture threshold (the energy sent from the pacemaker needed to make the heart's atrium beat) was measured at the 9-12 week visit (before the MRI scan was performed for those in the MRI group) and at the 4-month visit (one month post-MRI). Subjects were considered successful if their pacing capture threshold did not increase by 1.0 volt (V) or more.

Subjects were excluded from this analysis if: they did not have atrial pacing capture threshold measurements at 9-12 weeks or 4 months; or (for the MRI group) their MRI scan was not done according to protocol.

Subjects' ventricular pacing capture threshold (the energy sent from the pacemaker needed to make the heart's ventricle beat) was measured at the 9-12 week visit (before the MRI scan was performed for those in the MRI group) and at the 4-month visit (one month post-MRI). Subjects were considered successful if their pacing capture threshold did not increase by 1.0 volt (V) or more.

Subjects were excluded from this analysis if: they did not have ventricular pacing capture threshold measurements at 9-12 weeks or 4 months; or (for the MRI group) their MRI scan was not done according to protocol.

Subjects' atrial sensed amplitude (the minimum energy produced by the heart's atrium that the pacemaker can sense) was measured at the 9-12 week visit (before the MRI scan was performed for those in the MRI group) and at the 4-month visit (one month post-MRI). Subjects were considered successful if their sensed amplitude did not decrease by more than 50% and remained above 1.5 millivolts (mV).

Subjects were excluded from this analysis if: they did not have atrial sensed amplitude measurements at 9-12 weeks or 4 months; or (for the MRI group) their MRI scan was not done according to protocol; or if their 9-12 week atrial sensed amplitude was less than 1.5 mV.

Subjects' ventricular sensed amplitude (the minimum energy produced by the heart's ventricle that the pacemaker can sense) was measured at the 9-12 week visit (before the MRI scan was performed for those in the MRI group) and at the 4-month visit (one month post-MRI). Subjects were considered successful if their sensed amplitude did not decrease by more than 50% and remained above 5.0 millivolts (mV).

Subjects were excluded from this analysis if: they did not have ventricular sensed amplitude measurements at 9-12 weeks or 4 months; or (for the MRI group) their MRI scan was not done according to protocol; or if their 9-12 week ventricular sensed amplitude was less than 5.0 mV.

Subjects with a complication related to the implanted system, which consisted of the pacemaker, leads to the right chambers of the heart (atrium and ventricle), pacemaker software, and programmer. All adverse events in the time frame were recorded at the subject's center and assessed by a centralized Adverse Event Advisory Committee. The committee determined whether each adverse event was a complication (requiring invasive intervention), and whether the event was related to the system.

All implanted subjects with either a 4-month follow-up or a system-related complication within the first 4 months post-implant are included.

Number of participants with adverse device effects (ADEs) that resulted from insufficiencies or inadequacies in the instructions for use or deployment of the device, or from user error. ADE's were investigator-reported.

Includes all subjects undergoing an MRI using the instructions in the protocol.

Number of participants with sustained ventricular arrhythmias or asystole episodes that occurred during the MRI scan that were considered attributable to the MRI scan

Arrhythmia was defined as heart rate > 150 beats per minute for > 30 seconds. Asystole was defined as standstill 6 seconds in electrical activity of the heart. Episodes were assessed via pulse oximetry monitoring during MRI scans.

Subjects' atrial lead impedance (a measure of electrical resistance) was measured at the 9-12 week visit (before the MRI scan was performed for those in the MRI group) and at the 4-month visit (one month post-MRI). Both measurements were conducted by the pacemaker. The difference between the two is reported.

Subjects with non-missing data are included

Subjects' ventricular lead impedance (a measure of electrical resistance) was measured at the 9-12 week visit (before the MRI scan was performed for those in the MRI group) and at the 4-month visit (one month post-MRI). Both measurements were conducted by the pacemaker. The difference between the two is reported.

Subjects with non-missing data are included

Physicians' rated atrial lead handling during the implant on a scale of -3 to +3 where: -3 = well below expectations; -2 = moderately below expectations; -1 = slightly below expectations; 0 = met expectations; +1 = slightly above expectations; +2 = moderately above expectations; and +3 = well above expectations.

All surveys completed are included

Physicians' rated ventricular lead handling during the implant on a scale of -3 to +3 where: -3 = well below expectations; -2 = moderately below expectations; -1 = slightly below expectations; 0 = met expectations; +1 = slightly above expectations; +2 = moderately above expectations; and +3 = well above expectations.

All surveys completed are included

Average atrial pacing capture threshold. Pacing capture threshold is the energy needed to pace the heart.

Includes all subjects with data.

Average ventricular pacing capture threshold. Pacing capture threshold is the energy needed to pace the heart.

Average atrial sensed amplitude.

Average ventricular sensed amplitude.