Snapshot A 68-year-old male presents with palpitations, lightheadedness, and weakness. These symptoms appear to worsen with increased alcohol intake. Medical history is significant for hypertension being treated with hydrochlorothiazide. On physical exam, the patient appears uncomfortable. There is an irregularly irregular pulse when palpating the radial artery. On cardiac auscultation, the first heart sound (S1) is of variable intensity. There is mild bibasilar crackles on pulmonary auscultation and an absence of peripheral edema. An electrocardiagram is obtained. Introduction A supraventricular tachyarrhythmia secondary to uncoordinated atrial contractions results in an irregularly irregular rhythm non-repetitive pattern in the RR interval may reduce cardiac output may result in thrombus formation in the atrium most common site of origin for ectopic foci is pulmonary veins Pathogenesis usually due to an underlying cause e.g., atrial enlargement and inflammation or infiltrative disease affecting the atrium Causes include structural abnormalities e.g., left atrial enlargement, mitral and aortic stenosis, mitral and aortic regurgitation, and malignancy conduction abnormalities e.g., Wolff-Parkinson-White (WPW) syndrome medications theophylline and digoxin cardiac functional abnormalities e.g., myocardial infacrtion, pulmonary embolism, and coronary artery disease hyperthyroidism electrolyte disturbances e.g., hypomagnesemia and hypokalemia cardiomyopathies e.g., dilated and hypertrophic cardiomyopathy alcohol abuse ("holiday heart syndrome") post-operatively after heart surgery especially after coronary artery bypass grafting (CABG) Epidemiology most common arrhythmia Presentation Symptoms asymptomatic in symptomatic cases palpitations shortness of breath (suggesting heart failure) lightheadedness Physical exam irregularly irregular pulse focal neurological deficit if this results in an embolic stroke in cases of atrial fibrillation leading to heart failure elevated jugular venous pulse (JVP) bibasilar rales on pulmonary auscultation peripheral edema Evaluation Electrocardiogram (EKG or ECG) irregularly irregular rhythm absent P waves if arrhythmia is not captured on ECG then Holter monitoring in the outpatient setting these patients are hemodynamically stable telemitry in the inpatient setting Transthoracic echocardiogram (TTE) can assess atrial size and ventricular function, thickness, and size can also assess for valvular and pericardial disease, and peak right ventricular pressure transesophageal echocardiogram (TEE) is more sensitive in detecting thrombi in the left atrium Laboratory testing thyroid stimulating hormone (TSH) and free T4 level hyperthyroidism is a possible cause of atrial fibrillation electrolyte level Differential Multifocal atrial tachycardia (MAT) commonly seen in patients with pulmonary disease e.g., chronic obstructive pulmonary disease (COPD) Premature atrial contractions (PACs) associated with alcohol, caffeine, and nicotine use Atrial flutter Wolff-Parkinson-White syndrome Treatment Hemodynamically unstable patients synchronized cardioversion Hemodynamically stable patients slowing of the ventricular rate patients with new onset atrial fibrillation become symptomatic due to rapid ventricular response (except in cases of stroke) intravenous β-blockers or nondihydropyridine calcium channel blocker wheezing (COPD/asthma) use calcium channel blocker or titratable beta blocker (esmolol) long-term management rate control (preferred) β-blocker or nondihydropyridine calcium channel blocker treatment is chosen based on patient's comorbidities beta blocker preferred in coronary artery disease digoxin in heart failure with reduced ejection fraction rhythm control antiarrhythmics depends on patient's comorbidities anticoagulation in order to decrease the risk of thromboembolism stroke risk stratification CHA2DS2-VASc score Congestive heart failure = 1 point Hypertension = 1 point Age (75 years or older) = 2 points Diabetes = 1 point Stroke/transient ischemic attack/thromboembolism = 2 point Vascular disease = 1 point e.g., previous myocardial infarction and peripheral artery disease Age (65 - 74 years) = 1 point Sex category (female) = 1 point score of 0 or 1 use aspirin conservative monitoring score of 2 or more use oral anticoagulation dabigatran rivaroxaban apixaban novel anticoagulants contraindicated in renal failure warfarin international normalized ratio (INR) target of 2-3 only warfarin should be used with vascular lesions (eg. mechanical valves) Prognosis, Prevention, and Complications Prognosis increased risk of stroke Complications atrial mural thrombi emboli to cerebral vessels can cause ischemic stroke and transient ischemic attack atrial thrombus to common iliac artery requires immediate embolectomy to remove occlusion and preserve limb renal infarction sudden flank pain and tenderness wedge-shaped infarct on CT