Study variables
Dependent variables: Appropriate use of anti-thrombotic therapy in patients with AF.
Independent variables: 1) Socio demographic characteristics -age, sex, marital status, educational status and place of residence 2) Patient-related factors -eligibility for treatment, medication side effects, contra indication to treatment, and afford for INR monitoring 3) Clinical factors- heart failure, hypertension, diabetes, chronic kidney disease, CHA2DS2VASec score, type of AF, prior stroke/TIA, and hyperthyroidism.
Data collection instrument and procedures
Data were collected through an investigator administered pre-designed questionnaire. Patients were interviewed to obtain socio-demographic data. Focused clinical examination was done to each of study subjects. Relevant medical history and laboratory parameters were obtained from patients’ records. Diagnosis of atrial fibrillation was based on detection of irregular arterial pulse and ‘f’ waves on 12-lead ECG tracing. Clinical evaluation, echocardiography, chest X-ray and blood chemistry were used to diagnose underlying causes of AF.
Twelve-Lead ECG (ECG 1200G, YSIP-155, Beijing, China) were performed on all patients by physician with standardization of 1 mV = 10 mm and paper speed of 25 mm/sec. ECG-based AF diagnoses were reviewed by a cardiologist.
Two-Dimensional Doppler Transthoracic Echocardiography (B/W Digital Ultrasound Scanner, ARI group, China) was performed for AF patients with heart failure by a cardiologist to determine abnormalities on ventricular ejection fraction, valve morphology, ventricular wall size and motion, and atrial and ventricular chamber dimensions.
Venous blood samples were collected from AF patients in plain tubes and centrifuged at 2500 rpm for 15 min at room temperature to obtain serum. Serum glucose and creatinine were determined by enzymatic glucose oxidase and kinetic alkaline picrate method respectively using Mindray BS-480 (Shenzhen Mindray Bio-Medical electronics Co., Ltd., China) clinical chemistry analyzer. Thyroid function tests (TSH, T4 and T3) were determined in whom thyroid disorders were suspected. Thyroid function tests were determined using Radioimmunoassay (RIA) technique (Roche, Switzerland), and kits were from Beijing Isotope Nuclear Electronic Co., Beijing, China.
Definition of terms
Atrial fibrillation: ECG-evidenced cardiac rhythm disorder where the normal atrial ‘P’ waves are replaced by chaotic, fibrillatory ‘f’ waves. It was clinically detected by irregular arterial pulse and confirmed by 12-lead ECG tracing [
1,
2].
Anti-thrombotic therapy: Medications (anti-platelets and anticoagulants) which are given for patients with AF who are at high-risk of developing systemic embolic events.
Appropriateness to anti-thrombotic therapy: Patients are considered as appropriately treated with anti-thrombotic therapy when they are given oral anticoagulants for CHA
2DS
2VASc score ≥ 2, aspirin/oral anticoagulants for CHA
2DS
2VASc score of 1, no treatment for CHA
2DS
2VASc score of 0, oral anticoagulants for patients of valvular AF irrespective of the CHA
2DS
2VASc score, and oral anticoagulants for patients of hypertrophic cardiomyopathy with AF independent of the CHA
2DS
2VASc score. Patients with AF are inappropriately treated with anti-thrombotic therapy when they are not treated according to the above recommendation [
1,
2].
CHA2DS2VASc score: Congestive heart failure or left ventricular ejection fraction < 40% (score 1), hypertension (score 1), age ≥ 75 years (score 2), diabetes (score 1), prior stroke/TIA (score 2), vascular diseases (prior myocardial infarction, peripheral arterial disease or aortic plaque) (score 1), age 65–74 years (score 1), sex category (female, score 1).
Framingham criteria: Clinical criteria for heart failure diagnosis, and require presence of either two major, or one major and two minor criteria. Major criteria include paroxysmal nocturnal dyspnea, neck vein distension, acute pulmonary edema, positive hepatojugular reflex, rales, S3 gallop, increased venous pressure > 16 cmH20, cardiomegaly, and weight loss ≥4 kg in response to treatment. Minor criteria include nocturnal cough, dyspnea on ordinary exertion, pleural effusion, tachycardia (Pulse rate ≥ 120 bps), hepatomegaly, extremity edema, and vital capacity reduced by one-third from normal.
HAS-BLED score: Uncontrolled hypertension (score 1), abnormal kidney or liver disease (score 1, each), stroke (score 1), bleeding predisposition or tendency (score 1, each), labile INR (TTR < 60% score 1), elderly (age ≥ 65 years, score 1), and drugs or alcohol (score1, each). HAS-BLED score is used to assess the risk of bleeding, in which high risk patients (score ≥ 3) should be reviewed and followed frequently [
17].
TTR (Time in INR Therapeutic Range): The duration of time in which the patient’s international normalized range (INR) values were within a desired range (INR = 2–3).
Valvular-AF: AF in the presence of moderate to severe mitral stenosis, mechanical prosthetic valve, or mitral valve repair.
Non-valvular AF: AF in the absence of moderate to severe mitral stenosis, mechanical prosthetic valve, or mitral valve repair.
Hypertension: Presence of persistently elevated systolic blood pressure ≥ 140 mmhg and/or diastolic blood pressure ≥ 90 mmhg in patients aged 18 years of age and above, history of hypertension, or the use of anti-hypertensive drug(s).
Diabetes mellitus: Fasting serum glucose ≥126 mg/dl, history of diabetes, or use medications for diabetes.
Chronic kidney disease: Abnormalities of kidney structure or function present for more than 3 months, with implications for health. Diagnosis of chronic kidney disease was settled by clinical, biochemical (raised serum creatinine) and/or imaging (ultrasound-proven reduced kidney size) findings.
Heart failure: Clinical syndrome that results from any structural or functional impairment of ventricular filling or ejection of blood. The Framingham criteria were used to diagnose heart failure.
Stroke/TIA: Neurological deficit attributed to an acute focal injury of the central nervous system by a vascular cause. Diagnosis of stroke/TIA was settled by clinical and imaging (brain CT/MRI) evaluation.
Hyperthyroidism: Clinical state that involves excess synthesis and secretion of thyroid hormones by the thyroid gland. Diagnosis of hyperthyroidism was made in the presence of suggestive clinical symptoms and signs including enlarged thyroid gland, and confirmed by RIA test from serum revealing low TSH and/or raised T3/T4.