Table 1.

Comparison of device parameters at the time of magnetic resonance imaging and at 6 mo

Variable	Before MRI	Immediately after MRI: mean difference (95% CI)	P*	At 6 mo: mean difference (95% CI)	P†
Battery life
Volts	2.8	0.05 (−0.02 to 0.12)	.19 (n = 218)	−0.05 (−0.12 to 0.024)	.19 (n = 54)
Years	8.1	0.02 (−0.13 to 0.16)	.81 (n = 114)	−0.32 (−0.56 to −0.08)	.01 (n = 22)
Rate	77	0.00 (−9.00 to 9.00)	>.99 (n = 6)	−4.00 (−54.82 to 46.82)	.50 (n = 4)
Right atrial sensing (V)	2.9 ± 3.1	0.02 (−0.07 to 0.12)	.61 (n = 266)	−0.20 (−0.50 to 0.11)	.20 (n = 184)
Right atrial impedance (Ω)	458.0 ± 130.0	−4.02 (−10.86 to 2.82)	.25 (n = 281)	−2.28 (−10.96 to 6.41)	.60 (n = 193)
Right atrial threshold (mV)	0.8 ± 0.3	0.01 (−0.01 to 0.04)	.20 (n = 252)	0.07 (0.01 to 0.12)	.03 (n = 171)
Right ventricular sensing (V)	11.2 ± 7.6	−0.19 (−0.42 to 0.03)	.10 (n = 297)	0.31 (−0.49 to 1.12)	.44 (n = 202)
Right ventricular impedance (Ω)	481.0 ± 171.0	−54.14 (−9.27 to 0.98)	.11 (n = 353)	−3.70 (−17.44 to 10.05)	.60 (n = 238)
Right ventricular threshold (mV)	0.8 ± 0.5	−0.01 (−0.04 to 0.03)	.67 (n = 353)	0.04 (−0.03 to 0.12)	.25 (n = 236)
Coronary sinus sensing (V)	14.9 ± 6.4	−0.52 (−1.34 to 0.31)	.19 (n = 22)	−2.21 (−9.27 to 4.84)	.40 (n = 15)
Coronary sinus impedance (Ω)	680.5 ± 185.5	−9.25 (−23.64 to 5.14)	.19 (n = 39)	−25.90 (−83.14 to 33.34)	.30 (n = 25)
Coronary sinus threshold (mV)	1.0 ± 0.6	0.01 (−0.01 to 0.04)	.37 (n = 39)	0.08 (−0.32 to 0.48)	.49 (n = 23)

Numbers are expressed as mean ± SD (analysis unit is the MRI study). All comparisons of continuous data are made using mixed effects models, accounting for clustering of outcomes at an individual level. The number of observations used for each comparison is listed for each P value.

CI = confidence interval; MRI = magnetic resonance imaging.

^*P value for the comparison of post-MRI to pre-MRI.

^†P value for the comparison of 6 mo to pre-MRI.