Focus on cardiac arrhythmias and conduction disorders

Abstract

The sudden appearance of cardiac arrhythmias or the development of new conduction disorders always should trigger to look for underlying changes in myocardial perfusion and/or pump function, electrolyte or metabolic disturbances and electrophysiological side-effect of medications. Cardiac surgery is frequently complicated by the development of postoperative atrial fibrillation (AF) (in about 30 % of the patients after coronary artery bypass grafting and 50% after valve surgery) which is associated with an increased postoperative morbidity and mortality due to acute heart failure, stroke and other thrombo-embolic complications, ventricular arrhythmias. The current European Society of Cardiology (ESC) guidelines recommend betablocker therapy in all patients and prophylactic amiodarone therapy in high risk patients to prevent postoperative AF.1 Precise tools for assessing the risk for postoperative AF are however missing. In a prospective study of cardiac surgery patients in whom clinical, biological, ECG and transthoracic echocardiography data were preoperatively collected, history of AF and an indexed left atrial volume >32 ml/m2 were the strongest predictors of postoperative AF.2 In absence of previous AF indexed LV mass >110g/m2 was also an independent predictor. These findings suggest that preoperative echocardiography may allow a more accurate identification of high-risk patients who potentially may benefit from an improved prevention of postoperative AF by prophylactic amiodarone treatment. Moreover, as diastolic dysfunction with elevated left ventricular filling pressure is most probably the most frequent underlying cause responsible for the left atrial remodeling, the postoperative fluid balance should be more cautiously monitored in AF patients with dilated left atria and eventually preload reducing agents such as diuretics, nitrates or ACE-inhibitors administered in order to prevent too excessive swings in left atrial pressure that may trigger AF. Higher preoperative NT-pro brain natriuretic peptide levels were indeed strongly associated with the development of postoperative AF. Known permanent or new-onset AF is a relatively common comorbid condition or complication in patients with an acute coronary syndrome (ACS). A post-hoc analysis from the long-tErm follow-uP of antithrombotic management patterns In acute CORonary syndrome patients (EPICOR) registry (NCT01171404), a prospective, observational study conducted in Europe and Latin America, shows that in real life clinical practice patients with ACS and AF are less frequently treated with revascularization therapies, and that more than half do not receive oral anticoagulation at discharge, with a decline in use over time.3 They experienced a high event rate during long-term follow-up, with increased mortality, and cardiovascular and bleeding events compared with ACS patients without AF. Known permanent AF was a strong independent predictor of both mortality and the composite endpoint of death, nonfatal myocardial infarction or non-fatal stroke during the first 2 years after discharge, whereas new-onset AF was not. These findings indicate that the implementation of guideline-recommended therapies needs to be markedly improved in these high-risk ACS patients both during the initial hospitalization and follow-up. A literature review shows that the incidence of AF varies widely (1 to 44%) in patients hospitalized with an acute medical illness and is heavily dependent on the intensity of continuous ECG-monitoring.4 Recurrence rates after discharge are high (42 to 68%) and possibly also underestimated. Further prospective studies using systematic and sensitive AF detection strategies are needed to assess the incidence, recurrence rate and long-term clinical outcome of AF during an acute medical illness. Patients with recent-onset AF (>48 hours) are frequent visitors at the emergency department (ED). Early conversion without any delay may reduce the risk of thromboembolic complications and prevent electrical and mechanical left atrial remodeling. Pharmacological conversion of recent-onset AF is a valuable alternative for electric cardioversion without any need for anesthesia or fasting what may improve the patient flow at the ED. In a non-randomized retrospective study intravenous vernakalant was safe, almost two times more effective and Focus on cardiac arrhythmias and conduction disorders