Clinical Characteristics and Prognostic Factors of Atrial Fibrillation at a Tertiary Center of Pakistan - From a South-Asian Lens - a Retrospective Study.

It is a retrospective observational study done at Aga Khan University Hospital, Karachi, Pakistan, which is a tertiary care teaching hospital with a cardiology and cardiac surgery center. Aga Khan Hospital is one of the main referral health centers in Pakistan.

This study was approved by Aga Khan University ethical review committee (ERC No. # 2019-1008-2905).We reviewed hospital record files of 651 patients including both males and females, admitted in Aga Khan University Hospital from 1st July 2018 to 31st December 2018, who were found to have atrial fibrillation as a primary or associated diagnosis. Diagnosis of atrial fibrillation was confirmed on a 12 lead ECG. Fifteen patients were excluded who did not have electrocardiographic evidence of atrial fibrillation.

For all patient, demographic information including age and gender, reason of admission and duration of arrhythmia were noted from the written medical records. Comorbidities were tabulated including: diabetes mellitus, hypertension, coronary artery disease, heart failure, cardiomyopathy, valvular heart disease, chronic obstructive pulmonary disease, and hyperthyroidism. Echocardiographic data were reviewed for left atrial (LA) dimension, LA volume index and left ventricular (LV) systolic function.

Patients were labeled as Diabetic if they had HbA1c of >6.5gm/dl or they were already on treatment for diabetes mellitus. Hypertension was defined as average of two readings of systolic blood pressure of ≥140mmHg or diastolic blood pressure of ≥90mmHg or patients already taking antihypertensive medications. Coronary artery disease was defined as ≥50% stenosis in at least one of the epicardial coronary arteries. Cardiomyopathy was defined as left ventricular ejection fraction of ≤50% Chronic obstructive pulmonary disease was defined as forced expiratory volume in 1st second to forced vital capacity ratio of \<70% of the predicted value. Patients were labeled hyperthyroid if they have low serum TSH and high serum concentration of free T4 or T3 as per laboratory reference range.

All patients were followed from the time of inclusion to the time of discharge or till inpatient death. Hemodynamic parameters including heart rate and blood pressure were recorded at the time of inclusion for patients with known atrial fibrillation and at the time of onset of arrhythmia for those with new onset atrial fibrillation. Patients' treatment record were reviewed for medications. Complications related to atrial fibrillation or its treatment were recorded.