Atrial standstill in a patient with progressive severe heart failure

Atrial standstill (AS) is a very rare condition characterized by complete loss of electrical and mechanical activity and excitability of the atria. Absence of P waves, bradycardia and junctional escape rhythm may suggest AS on surface ECG. In nearly half of the reported cases, the condition manifested with syncope [1, 2]. AS must be differentiated from common sinus node disease with sinus arrest or highgrade sinoatrial block that may have similar symptoms and surface ECG presentation [3]. AS has been rarely described to be primary with familial clustering and/or associated cardiac ion channel mutations [2, 4]. More commonly, it has been linked to heart disorders such as myocarditis, ischemic heart disease, or dilated cardiomyopathy [5–7]. AS occurring in the context of structural myocardial disease may indicate a poor prognosis [1, 8]. A 48-year-old female patient was referred to our emergency department due to fatigue, progressive dyspnoea on exertion and recurring syncope since a few months. Three years earlier she had presented to our outpatient clinic for recurrent pulmonary infections, where a normal ECG had been registered (Fig. 1a). Four months before she had been hospitalized at an external institution for ascites and pleural effusion of unknown origin and atrial fibrillation was diagnosed on surface ECG. A diuretic as well as oral anticoagulation were initiated. At presentation, the patient reported no family history of syncope or sudden death, and physical examination revealed cachexia (BMI 18.6 kg/m), but no obvious cardiopulmonary pathologies. Shortly after admission, the patient exhibited rapid polymorphic ventricular tachycardia (VT), requiring CPR and defibrillation. Twelve-lead surface ECG, recorded prior the arrhythmic event, showed absence of P waves with an escape rhythm of 48/min, a QRS duration of 70 ms, constant R–R intervals, and a prolonged QT interval of 600 ms (QTc 536 ms) (Fig. 1b). Laboratory findings revealed mild hypokalemia (3.2 mmol/ L), slightly elevated liver enzymes, an INR value of 2.1, N-terminal pro-BNP of 1,465 pg/mL (7.39 of normal value) and an ANP of 2.89 nmol/L (1.59 of normal value), whereas normal values were found for calcium, blood cell count, CRP, renal and thyroid functional parameters and CK. Chest X-ray revealed marked cardiomegaly, and the echocardiogram showed a dilated left ventricle with a severely reduced left ventricular ejection fraction (LVEF) of 20 %. Of note, LVEF had been reported to be 45 and 60 %, 2 and 3 months earlier, respectively. Furthermore, echocardiography showed dilated right and left atria along with moderate to severe tricuspid and moderate mitral regurgitation. A transesophageal echocardiogram revealed a thrombus in the left atrial appendage, where no significant flow was identifiable with Doppler imaging (Fig. 1c, d). Few hours after admission, the patient again developed recurrent polymorphic VT with syncope and need for defibrillation despite normalization of potassium levels (Fig. 1e). Coronary artery disease was ruled out angiographically and a temporary transvenous pacemaker was inserted. Myocardial biopsies were taken from the right ventricle, but provided no evidence for acute myocarditis [9], arrhythmogenic right ventricular dysplasia [10], amyloidosis or hemosiderosis. This was in line with findings from cardiac MRI, so that idiopathic dilated cardiomyopathy was diagnosed. With ventricular overdrive pacing at 80 bpm and initiation of beta-blocker medication VT did M. R. Schroeter (&) G. Hasenfus M. Zabel D. Vollmann Abt. Kardiologie und Pneumologie, Universitatsmedizin Gottingen, Herzzentrum, Robert-Koch-Str. 40, 37099 Gottingen, Germany e-mail: mschroeter@med.uni-goettingen.de