Table 1

Population characteristics in London and California

Variable	London	California	P value
	Per patient	Per patient
	(n=361)	(n=619)
Age (years, mean±SD)	60±11	63±10	0.001*
Female sex	98 (27)	153 (25)	0.401
Body mass index (kg/m², mean±SD)	29±6	30±5	0.133
Long-standing persistent AF (>1 year)	105 (29)	157 (25)	0.204
Left atrial diameter (mm, mean±SD)†	47±8	45±7	<0.0001*
Left ventricular function			<0.0001*
Normal	232 (64)	448 (72)
Mildly impaired	50 (14)	122 (20)
Moderately impaired	38 (11)	33 (5)
Severely impaired	41 (11)	16 (3)
Valvular heart disease‡	38 (11)	49 (8)	0.166
Extreme comorbidity§	39 (11)	27 (4)	0.0001*
Hypertension	105 (29)	318 (51)	<0.0001*
Diabetes mellitus	29 (8)	67 (11)	0.156
Coronary artery disease	53 (15)	90 (15)	1.000
Thyrotoxicosis within the last year¶	11 (3)	13 (2)	0.355
Pulmonary disease	10 (3)	38 (6)	0.002*
Stroke or TIA	21 (6)	48 (6)	0.253
Renal dysfunction	5 (1)	N/A	N/A
Previous antiarrhythmic drugs (median(IQR))**	1 (0–1)	1 (1–2)	<0.0001*
Previous use of amiodarone	115 (32)	209 (34)	0.540
FLAME score (mean±SD)	2.9±1.7	2.5±1.6	<0.0001*

	Per procedure	Per patient
	(n=416)	(n=619)
Follow-up (months, mean±SD/median (IQR))	12±3	25 (12–50)	<0.0001*

Values shown are number (%) unless otherwise indicated. Per patient values are calculated at the time of a patient’s first procedure.
*Statistically significant p<0.05.
†Transthoracic echocardiographic left parasternal long axis anteroposterior diameter at end-systole.
‡Moderate or greater stenosis or regurgitation, replacement or repair of any left-sided valve.
§See figure 1 for definition
¶Thyrotoxic within the last year.
**Class I or III agents.
AF, atrial fibrillation; FLAME, Female, Long-lasting, Atrial diameter, Mitral, Extreme; N/A, not available; TIA, transient ischaemic attack.