Incidence and diagnosis of patients developing atrial fibrillation in intensive care

Introduction

Atrial fibrillation (AF) is a common arrhythmia encountered in critically ill patients. In this study we evaluated the incidence and risk factors associated with the occurrence of AF in a general ICU.

Methods

One hundred and ten patients admitted to the ICU during a 3-month period were screened for AF. Case notes and daily management charts of these patients were analysed retrospectively.

Results

Twenty-nine (26.3%) out of 110 patients developed AF. The mean age of patients was 71.8 (± 9.2) years and the APACHE II score was 21.3 (± 6.3). Electrolytes were within the normal range in 85% of the patients. The main cardiac factors identified in our patients with AF were hypertension (71.4%) and coronary artery disease (48.3%). Less commonly encountered cardiac diagnoses were congenital heart disease and history of previous atrial fibrillation. Inotropic support and sepsis were the leading noncardiac factors found in 24 (82.8%) and 22 (75.9%) patients, respectively. Diabetes mellitus and obesity contributed in 17.2% of patients.

Troponin T was determined in 13 patients and found to be elevated in 10 patients (34.5% of AF patients). Transthoracic echocardiography was performed on 10 patients with persistent AF (34.5%). Seven patients had valve pathology whereas left ventricular dysfunction was present in five patients. Only one echocardiography was reported normal. Patients were treated according to local guidelines with amiodarone (19 (65.5%)), digoxin (5 (17.2%)) and β-blockers (4 (13.8%)), and DC cardio-version was used in only one patient. Eighteen (62.1%) patients were successfully cardioverted.

Conclusion

Apart from known risk factors for AF such as increased age, hypertension or ischaemic heart disease, sepsis and inotropes increase susceptibility for AF. Less frequently associated causes such as congenital heart disease, obesity and diabetes can contribute towards AF. Echocardiography could reveal less obvious causes of AF like valvular pathologies and left ventricular dysfunction, and could be a useful diagnostic tool in critically ill patients with AF.