Stroke rates before and after ablation of atrial fibrillation and in propensity-matched controls in the UK

Figures & data

Table 1 Baseline patient characteristics

Characteristics	PVA vs AF match (N=4,991 per cohort)		PVA vs CV match (N=5,407 per cohort)
	PVA	AF Control	PVA	CV Control
CHADS2 risk scorea
0	62.8%	63.0%	58.7%	58.9%
1	29.2%	29.1%	32.6%	32.7%
2	6.9%	7.0%	7.4%	7.1%
3	1.0%	0.8%	1.1%	1.1%
4	0.1%	0.2%	0.1%	0.1%
≥5	0.0%	0.0%	0.0%	0.0%
CHA2DS2-VASc risk scorea
0	34.6%	33.8%	33.5%	33.5%
1	30.9%	31.7%	30.6%	30.8%
2	19.4%	19.9%	19.8%	20.0%
3	10.3%	10.1%	11.1%	10.9%
4	3.4%	3.4%	3.6%	3.8%
5	1.2%	0.9%	1.2%	0.9%
6	0.2%	0.1%	0.2%	0.1%
≥7	0.0%	0.0%	0.0%	0.0%
Age group at index date
<35	3.0%	3.2%	2.6%	2.6%
35 to <45	9.1%	8.8%	8.1%	8.1%
45 to <55	22.6%	22.5%	21.5%	21.4%
55 to <65	35.9%	36.2%	37.3%	37.4%
65 to <75	25.4%	24.9%	26.4%	26.4%
75 to <85	4.0%	4.2%	4.0%	4.0%
85+	0.1%	0.2%	0.1%	0.1%
Sex
Female	30.9%	30.9%	29.6%	29.6%
Male	69.1%	68.9%	70.4%	70.4%
Undetermined	0.0%	0.2%	0.0%	0.0%
Year of index date
2007	2.0%	2.3%	2.0%	1.9%
2008	6.8%	6.5%	6.4%	6.7%
2009	10.2%	10.5%	9.7%	9.4%
2010	12.7%	13.9%	12.8%	12.8%
2011	17.8%	17.7%	17.5%	17.4%
2012	23.4%	23.2%	23.3%	23.4%
2013	24.9%	24.3%	26.3%	26.3%
2014	2.3%	1.6%	2.1%	2.1%
Months from first AF to index dateb
Mean	15	15	21	5
Median	9	9	13	0
Interquartile range	0–22	0–22	0–33	0–5
Months of follow-up after index datec
Mean	28.1	28.9	27.5	27.8
Median	24.0	25.0	24.0	23.0
Interquartile range	11–42	12–44	11–41	11–42

Notes:

a Based on diagnoses and procedures recorded within 3 years prior to the index date;

b first AF is based on a diagnosis seen in a hospital setting;

c follow-up is measured through the end of 2013.

Abbreviations: AF, atrial fibrillation; CV, cardioversion; PVA, pulmonary vein ablation.

Table 2 Sample sizes and reasons for loss to follow-up by year

PVA vs General AF match
Follow-up	Population size with utilizationa		Died in hospital during the year		Data ended prior to end of year
	AF control	PVA cohort	AF control	PVA cohort	AF control	PVA cohort
±1 year	2,444	3,083	60	7	1,289	1,355
±2 years	1,572	1,819	28	7	512	868
±3 years	963	1,072	29	5	384	521
±4 years	527	572	9	1	235	320
±5 years	227	242	9	0	213	240
PVA vs CV match
Follow-up	Population size with utilizationa		Died in hospital during the year		Data ended prior to end of year
	CV control	PVA cohort	CV control	PVA cohort	CV control	PVA cohort
±1 year	3,049	3,319	16	10	1,533	1,534
±2 years	1,876	1,944	17	7	832	949
±3 years	1,137	1,147	9	4	521	562
±4 years	599	598	11	1	342	359
±5 years	275	254	3	0	228	250

Notes:

a Follow-up is measured through the last date of hospital utilization only.

Abbreviations: AF, atrial fibrillation; CV, cardioversion; PVA, pulmonary vein ablation.

Figure 1 Yearly observed stroke rates in matched cohorts. (A) PVA vs matched general AF cohorts; (B) PVA vs matched cardioversion cohorts.

Abbreviations: AF, atrial fibrillation; PVA, pulmonary vein ablation.

Table 3 Repeated measures logistic regression model resultsa

Model estimates of stroke rates	Adjusted overall mean	Standard error of mean	p-value for cohort comparison
PVA vs general AF match
Preindex model
PVA cohort	0.30%	0.08%	0.8292
Control cohort	0.28%	0.07%
Postindex model
PVA cohort	0.64%	0.11%	<0.0001
Control cohort	1.84%	0.23%
PVA vs cardioversion match
Preindex model
PVA cohort	0.37%	0.09%	0.5198
Control cohort	0.42%	0.08%
Postindex model
PVA cohort	0.82%	0.15%	0.0222
Control cohort	1.37%	0.18%

Notes:

a Models included cohort and year as predictors, with year as a categorical variable and cohort–year interaction included only when statistically significant.

Abbreviations: AF, atrial fibrillation; PVA, pulmonary vein ablation.

Table S1 Diagnosis or procedure codes

Diagnosis or procedure	Definition
Ablation – atrial flutter	Any of the following OPCS-4 codes appear in any procedure field:
	K622 – Percutaneous transluminal ablation of atrial wall for atrial flutter
	K623 – Percutaneous transluminal ablation of conducting system of heart for atrial flutter NEC (April 2007 onward)
Ablation – atrioventricular node	Any of the following OPCS-4 codes appear in any procedure field:
	K521 – Open ablation of atrioventricular node
	K571 – Percutaneous transluminal ablation of atrioventricular node
Ablation – other foci	Any of the following OPCS-4 codes appear in any procedure field:
	K574 – Percutaneous transluminal ablation of accessory pathway (April 2006 onward)
	K575 – Percutaneous transluminal ablation of atrial wall NEC (April 2006 onward)
	K578 – Other specified other therapeutic transluminal operations on heart
Ablation – pulmonary vein	Any of the following OPCS-4 codes appear in any procedure field:
	K621 – Percutaneous transluminal ablation of pulmonary vein to left atrium conducting system (April 2007 onward)
Atrial fibrillation or flutter	Any of the following ICD-10 codes appear in any diagnosis field:
	I48X – Atrial fibrillation or flutter
Cardiomyopathy	Any of the following ICD-10 codes appear in any diagnosis field:
	I42 – Cardiomyopathy
	I43 – Cardiomyopathy in diseases classified elsewhere
	I255 – Ischemic cardiomyopathy
Cardiomyopathy – hypertrophic	Any of the following ICD-10 codes appear in any diagnosis field:
	I421 – Obstructive hypertrophic cardiomyopathy
	I422 – Other hypertrophic cardiomyopathy
Cardioversion	Any of the following OPCS-4 codes appear in any procedure field:
	X501 – Direct current cardioversion
	X502 – External cardioversion NEC
Chronic kidney disease	Any of the following ICD-10 codes appear in any diagnosis field:
	I12 – Hypertensive renal disease
	I13 – Hypertensive heart and renal disease
	N18 – Chronic kidney disease
COPD	Any of the following ICD-10 codes appear in any diagnosis field:
	J439 – Emphysema, unspecified
	J44 – Other chronic obstructive pulmonary disease
Coronary artery bypass graft	Any of the following OPCS-4 codes appear in any procedure field:
	K40 – Saphenous vein graft replacement of coronary artery
	K41 – Other autograft replacement of coronary artery
	K42 – Allograft replacement of coronary artery
	K43 – Prosthetic replacement of coronary artery
	K44 – Other replacement of coronary artery
	K45 – Connection of thoracic artery to coronary artery
	K46 – Other bypass of coronary artery
Coronary artery disease	Any of the following ICD-10 codes appear in any diagnosis field:
	I20 – Angina pectoris
	I21 – Acute myocardial infarction
	I22 – Subsequent myocardial infarction
	I23 – Certain current complications following acute myocardial infarction
	I24 – Other acute ischemic heart diseases
	I25 – Chronic ischemic heart disease
	Z951 – Presence of aortocoronary bypass graft
Diabetes mellitus	Any of the following ICD-10 codes appear in any diagnosis field:
	E10 – Insulin-dependent diabetes mellitus
	E11 – Noninsulin-dependent diabetes mellitus
	E12 – Malnutrition-related diabetes mellitus
	E13 – Other specified diabetes mellitus
	E14 – Unspecified diabetes mellitus
Heart failure	Any of the following ICD-10 codes appear in any diagnosis field:
	I110 – Hypertensive heart disease with (congestive) heart failure
	I130 – Hypertensive heart and renal disease with (congestive) heart failure
	I132 – Hypertensive heart and renal disease with both (congestive) heart failure and renal failure
	I50 – Heart failure
Hyperlipidemia	Any of the following ICD-10 codes appear in any diagnosis field:
	E780 – Pure hypercholesterolemia
	E781 – Pure hyperglyceridemia
	E782 – Mixed hyperlipidemia
	E783 – Hyperchylomicronemia
	E784 – Other hyperlipidemia
	E785 – Hyperlipidemia, unspecified
Hypertension	Any of the following ICD-10 codes appear in any diagnosis field:
	I10 – Essential (primary) hypertension
	I11 – Hypertensive heart disease
	I12 – Hypertensive renal disease
	I13 – Hypertensive heart and renal disease
	I15 – Secondary hypertension
Obesity	Any of the following ICD-10 codes appear in any diagnosis field:
	E66 – Obesity
Other arrhythmias/conduction disorders	Any of the following ICD-10 codes appear in any diagnosis field:
	I44 – Atrioventricular and left bundle-branch block
	I45 – Other conduction disorders
	I47 – Paroxysmal tachycardia
	I49 – Other cardiac arrhythmias
Other operations on the heart conduction system	Any of the following OPCS-4 codes appear in any procedure field:
	K522 – Epicardial excision of rhythmogenic focus
	K523 – Endocardial excision of rhythmogenic focus
	K524 – Open division of accessory pathway within heart
	K525 – Open division of conducting system of heart NEC
	K528 – Other specified open operations on conducting system of heart
	K529 – Unspecified open operations on conducting system of heart
	K572 – Percutaneous transluminal ablation of conducting system of heart NEC
	K573 – Percutaneous transluminal removal of foreign body from heart (April 2006 onward)
Pacemaker or implantable cardioverter defibrillator (ICD)	Any of the following OPCS-4 codes appear in any procedure field:
	K591 – Implantation of cardioverter defibrillator using one electrode lead
	K592 – Implantation of cardioverter defibrillator using two electrode leads
	K593 – Resiting of lead of cardioverter defibrillator
	K594 – Renewal of cardioverter defibrillator
	K595 – Removal of cardioverter defibrillator
	K596 – Implantation of cardioverter defibrillator using three electrode leads
	K598 – Other specified cardioverter defibrillator introduced through the vein
	K599 – Unspecified cardioverter defibrillator introduced through the vein
	K601 – Implantation of intravenous cardiac pacemaker system NEC
	K602 – Resiting of lead of intravenous cardiac pacemaker system
	K603 – Renewal of intravenous cardiac pacemaker system
	K604 – Removal of intravenous cardiac pacemaker system
	K605 – Implantation of intravenous single chamber cardiac pacemaker system
	K606 – Implantation of intravenous dual chamber cardiac pacemaker system
	K607 – Implantation of intravenous biventricular cardiac pacemaker system
	K608 – Other specified cardiac pacemaker system introduced through vein
	K609 – Unspecified cardiac pacemaker system introduced through vein
	K611 – Implantation of cardiac pacemaker system NEC
	K612 – Resiting of lead of cardiac pacemaker system NEC
	K613 – Renewal of cardiac pacemaker system NEC
	K614 – Removal of cardiac pacemaker system NEC
	K615 – Implantation of single chamber cardiac pacemaker system
	K616 – Implantation of dual chamber cardiac pacemaker system
	K617 – Implantation of biventricular cardiac pacemaker system
	K618 – Other specified other cardiac pacemaker system
	K619 – Unspecified other cardiac pacemaker system
	U311 – Distant pacemaker test
	U318 – Other specified pacemaker testing
	U319 – Unspecified pacemaker testing
	OR
	Any of the following ICD-10 codes appear in any diagnosis field:
	Z450 – Adjustment and management of cardiac pacemaker
	Z950 – Presence of cardiac pacemaker
Percutaneous coronary intervention	Any of the following OPCS-4 codes appear in any procedure field:
	K49 – Transluminal balloon angioplasty of coronary artery
	K50 – Other therapeutic transluminal operations on coronary artery
	K75 – Percutaneous transluminal balloon angioplasty and insertion of stent into coronary artery (only available from April 2006)
Peripheral vascular disease (PVD)	Any of the following ICD-10 codes appear in any diagnosis field:
	I70 – Atherosclerosis
	I71 – Aortic aneurysm and dissection
	I72 – Other aneurysm and dissection
	I73 – Other peripheral vascular diseases
	I74 – Arterial embolism and thrombosis
	I798 – Other disorders of arteries, arterioles, and capillaries in diseases classified elsewhere
Pulmonary disease	Any of the following ICD-10 codes appear in any diagnosis field:
	I26 – Pulmonary embolism
	I27 – Other pulmonary heart diseases
	I28 – Other diseases of pulmonary vessels
Sleep apnea	Any of the following ICD-10 codes appear in any diagnosis field:
	G473 – Sleep apnea
Stroke – hemorrhagic	Any of the following ICD-10 codes appear in any diagnosis field:
	I60 – Subarachnoid hemorrhage
	I61 – Intracerebral hemorrhage
	I62 – Other nontraumatic intracranial hemorrhage
Stroke – ischemic	Any of the following ICD-10 codes appear in any diagnosis field:
	I63 – Cerebral infarction
	I64X – Stroke, not specified as hemorrhage or infarction
Transient ischemic attack	Any of the following ICD-10 codes appear in any diagnosis field:
	G45 – Transient cerebral ischemic attacks and related syndromes
Valvular disease	Any of the following OPCS-4 codes appear in any procedure field:
	K253 – Prosthetic replacement of mitral valve
	K263 – Prosthetic replacement of aortic valve
	OR
	Any of the following ICD-10 codes appear in any diagnosis field:
	I05 – Rheumatic mitral valve diseases
	I06 – Rheumatic aortic valve diseases
	I07 – Rheumatic tricuspid valve diseases
	I08 – Multiple valve diseases
	I091 – Rheumatic diseases of endocardium, valve unspecified
	I34 – Nonrheumatic mitral valve disorders
	I35 – Nonrheumatic aortic valve disorders
	I36 – Nonrheumatic tricuspid valve disorders
	I37 – Pulmonary valve disorders
	I38 – Endocarditis, valve unspecified
	I39 – Endocarditis and heart valve disorders in diseases classified elsewhere
	Z952 – Presence of prosthetic heart valve
	Z953 – Presence of xenogenic heart valve
Vascular disease	Any of the components in these fields:
	Coronary artery disease
	Peripheral vascular disease
	Coronary artery bypass graft
	Percutaneous coronary intervention

Abbreviations: NEC, not elsewhere classified; ICD, International Classification of Diseases; OPCS, Office of Population Censuses and Surveys.