Plasma Big Endothelin-1 Levels and Long-Term Outcomes in Patients With Atrial Fibrillation and Acute Coronary Syndrome or Undergoing Percutaneous Coronary Intervention

The impact of new-onset atrial fibrillation in the setting of acute coronary syndrome

Approximately 10 % of patients who have suffered from myocardial infarction develop new-onset atrial fibrillation (AF). Coronary artery disease implicating atrial branches has been associated with AF. The following variables have been associated with new-onset AF in the setting of acute coronary syndrome: older age, history of hypertension, history of angina, history of stroke, chronic renal failure, body mass index, no statin use, worse nutritional status, worse Killip class, admission heart rate ≥ 85 bpm, complete atrioventricular block, Glasgow prognostic score, Syntax score, C2HEST score > 3, PRECISE-DAPT score ≥ 25, left ventricular ejection fraction ≤40 %, increased left atrial diameter, E/E' ratio > 12, epicardial fat tissue thickness, and thrombolysis in myocardial infarction flow < 3. Regarding laboratory variables, elevated D-dimer levels, C-reactive protein levels, N-terminal pro-B-type natriuretic peptide, creatine kinase-MB, high-sensitivity troponin T at baseline, midregional pro-atrial natriuretic peptide, and cholesterol levels have been proposed as potential predictors of AF in this setting. Regarding the impact of new-onset AF on clinical outcomes, it has been associated with an increased risk of stroke, higher mortality rates, heart failure, cardiogenic shock, higher odds of ventricular arrhythmias and major adverse cardiac events. New-onset AF is an indicator of worse in-hospital prognosis compared to patients with a previous history of AF. New-onset AF, as well as previous AF, were strong predictors of ischemic stroke, and therefore, patients with new-onset AF should be anticoagulated according to the CHA2DS2-VASc score. Cardioversion to sinus rhythm, if possible, is advised before the discharge as it may be related to better outcomes.

Coronary microvascular dysfunction, arrythmias, and sudden cardiac death: A literature review

The coronary vascular system has a unique structure and function that is adaptive to myocardial demand. It is composed of a continuous network of vessels receding in size from epicardial arteries to the microvascular circulation. Failure to meet myocardial demand results in ischemia, angina, and adverse myocardial outcomes. It is evident that 50 % of patients with angina have a non-obstructive coronary disease and 66 % of these patients have coronary microvascular dysfunction (CMD). The impact of CMD on the atria and ventricles is exhibited through its association with atrial fibrillation and distortion of ventricular repolarization. Ultimately, this influence increases the risk of mortality, morbidity, and sudden cardiac arrest. CMD serves as an independent risk for atrial fibrillation, increases ventricular electrical inhomogeneity, and contributes to the progression of cardiac disease. The underlying pathogenesis may be attributed to oxidative stress evident through reactive oxygen species, impaired vasoactive function, and structural disorders such as fibrotic changes. Myocardial ischemia, brought about by a demand-supply mismatch in CMD, may create a milieu for ventricular arrythmia and sudden cardiac arrest through distortion of ventricular repolarization parameters such as QT dispersion and corrected QT dispersion.