Incidence, type of atrial fibrillation and risk factors for stroke: a population-based cohort study

Figures & data

Figure 1 Flow chart showing the patients with atrial fibrillation or atrial flutter (AF) who were included in this study.

Abbreviation: ICD-10, the International Classification of Diseases-10.

Figure 2 The incidence of first-diagnosed atrial fibrillation or atrial flutter (AF) according to age group and sex.

Table 1 Baseline table showing characteristics of 607 patients with first-diagnosed atrial fibrillation or atrial flutter (AF)

Age at diagnosis, years (mean)	73.5±12.2
Female sex	257 (42.3)
Congestive heart failure	110 (18.1)
Hypertension	380 (62.6)
Diabetes mellitus	101 (16.6)
Previous stroke, TIA or arterial embolism	113 (18.6)
Vascular diseasea	126 (20.8)
CHA2DS2-VASc, mean	3.3±1.9
CHA2DS2-VASc 0 points	42 (6.9)
CHA2DS2-VASc 1 point	75 (12.4)
CHA2DS2-VASc ≥2 points	490 (80.7)

Notes:

a Previous myocardial infarction, objectively verified peripheral arterial disease, complex aortic plaque or previous surgery for an arterial aneurysm. CHA₂DS₂-VASc score for AF stroke risk: congestive heart failure, hypertension, age ≥75 years (scored as 2 points), diabetes mellitus, previous stroke/TIA/arterial embolism (scored as 2 points), vascular disease, age 65–74 years and female sex. Data are reported as n (%) or as mean ± standard deviation.

Abbreviation: TIA, transient ischemic attack.

Table 2 Characteristics of 607 patients with and without a provoking factor associated with first-diagnosed atrial fibrillation or atrial flutter (AF)

	Cardiac surgery; n = 46	Non-cardiac surgery; n = 21	Acute infection n = 24	Myocardial infarction; n = 16	Othera n = 18	No provoking factor; n = 482
Age, years, mean ± standard deviation	68.0±10.7	73.6±10.8	73.3±14.2	78.3±8.5	76.3±10.6	73.8±12.3
Female sex, n (%)	12 (26.1)	8 (38.1)	10 (41.7)	6 (37.5)	11 (61.1)	210 (43.6)
Deceased, n (%)	2 (4.3)	0 (0)	8 (33.3)	4 (25.0)	5 (27.8)	49 (10.2)

Notes:

a Other types of provoking factors included anemia (six patients), thyrotoxicosis or overdosage of levothyroxine (four patients), dehydration (two patients), acute abdominal pain (two patients), high tumor burden (two patients), aortic aneurysm (one patient) and status epilepticus (one patient). Data are reported as n (%) or mean ± standard deviation.

Table 3 Type of atrial fibrillation and atrial flutter (AF) in 607 patients with first-diagnosed AF

Types of AF
	Single episode of AF, n = 147	Paroxysmal AF, n = 123	Persistent AF, n = 138	Permanent AF, n = 197
Age, years, mean ± standard deviation	74.3±13.0	74.4±9.5	67.1±12.9	78.4±10.1
Female sex, n (%)	64 (43.5)	65 (52.8)	46 (33.3)	81 (41.1)
Provoking factor, n (%)a	45 (30.6)	23 (18.7)	37 (26.8)	22 (11.2)
CHA2DS2-VASc, mean ± standard deviation	3.2±1.9	3.4±1.7	2.6±1.8	3.7±1.8
Deceased, n (%)	16 (10.9)	10 (8.1)	2 (1.4)	39 (19.8)

Notes: Two patients had unclassified AF and are not shown in this table.

a Provoking factor in association with the first-diagnosed episode of AF. CHA₂DS₂-VASc score for AF stroke risk: congestive heart failure, hypertension, age ≥75 years (scored as 2 points), diabetes mellitus, previous stroke/TIA/arterial embolism (scored as 2 points), vascular disease, age 65–74 years and female sex. Data are reported as n (%) or as mean ± standard deviation.

Table S1 Detailed definitions of risk factors for stroke and systemic embolism and provoking factors for AF

Condition	Definition
Risk factors for stroke and systemic embolism:
Congestive heart failure	ICD-10 diagnosis of congestive heart failure or LVEF ≤40% or at least moderately decreased left ventricular systolic function
Hypertension	ICD-10 diagnosis of hypertension or receiving antihypertensive treatment
Diabetes mellitus	ICD-10 diagnosis of diabetes mellitus or a diagnosis of diabetes mellitus in the medical record
Previous stroke	ICD-10 diagnosis of stroke or a diagnosis of stroke in the medical record
Previous TIA	ICD-10 diagnosis of TIA or diagnosis of TIA in the medical record plus sudden onset of neurological symptoms and/or signs that lasted less than 24 hours
Previous arterial embolism	ICD-10 diagnosis of arterial embolism or a diagnosis of arterial embolism in the medical record
Vascular disease	Previous myocardial infarction, objectively verified peripheral arterial disease (verified by appropriate imaging or treated with revascularization or amputation), complex aortic plaque or previous surgery for an arterial aneurysm
Provoking factors for the first episode of AF:
Cardiac surgery	All types of cardiac surgery performed within 30 days preceding the first-diagnosed episode of AF (valvular repair or replacement surgery, coronary artery bypass grafting, percutaneous coronary intervention included)
Non-cardiac surgery	All types of non-cardiac surgery performed within 30 days before the first-diagnosed episode of AF
Acute infection	A diagnosis of an acute infection in the medical record at the same time as the first-diagnosed episode of AF
Myocardial infarction	A diagnosis of a myocardial infarction in the medical record at the same time as the first-diagnosed episode of AF
Anemia	Anemia noted in the medical record at the same time as the first-diagnosed episode of AF
Thyrotoxicosis or overdosage of levothyroxine	Thyrotoxicosis or overdosage of levothyroxine noted in the medical record as a provoking factor for the first episode of AF at the same time as the first-diagnosed episode of AF
Dehydration	Dehydration noted in the medical record as a provoking factor for the first episode of AF at the same time as the first-diagnosed episode of AF
Acute abdominal pain	Acute abdominal pain noted in the medical record as a provoking factor for the first episode of AF at the same time as the first-diagnosed episode of AF
High tumor burden	High tumor burden noted in the medical record as a provoking factor for the first episode of AF at the same time as the first-diagnosed episode of AF
Aortic aneurysm	Aortic aneurysm noted in the medical record as a provoking factor for the first episode of AF at the same time as the first-diagnosed episode of AF
Status epilepticus	Status epilepticus noted in the medical record as a provoking factor for the first episode of AF at the same time as the first-diagnosed episode of AF

Abbreviations: AF, atrial fibrillation or atrial flutter; ICD-10, the International Classification of Diseases-10; LVEF, left-ventricular ejection fraction; TIA; transient ischemic attack.

Table S2 Incidence of first-diagnosed atrial fibrillation and atrial flutter presented as number of incident cases per two years and incidence per 1,000 person-years, by age and sex

Age, years	Men			Women
	Total population	Incident cases	Incidence	Total population	Incident cases	Incidence
0–19	8,655	0	0	8,186	0	0
20–29	4,539	1	0.11	3,927	1	0.13
30–39	4,340	6	0.69	4,011	1	0.12
40–44	2,439	6	1.23	2,313	2	0.43
45–49	2,522	7	1.39	2,451	3	0.61
50–54	2,436	10	2.05	2,482	5	1.01
55–59	2,618	31	5.92	2,592	6	1.16
60–64	2,596	41	7.90	2,497	13	2.60
65–69	2,365	57	12.05	2,406	27	5.61
70–74	1,659	60	18.08	1,877	36	9.59
75–79	1,189	42	17.66	1,598	46	14.39
80–84	802	39	24.31	1,265	54	21.34
85–89	453	31	34.22	738	43	29.13
90–94	91	18	98.90	311	17	27.33
95–99	18	1	27.78	61	3	24.59
100+	0	0	0	4	0	0