Surface ECG interatrial block-guided treatment for stroke prevention: rationale for an attractive hypothesis

Abstract

Atrial fibrillation (AF) is the most common sustained arrhythmia and is associated with stroke, cognitive impairment, and cardiovascular death. Some predisposing factors − as aging, diabetes, hypertension − induce and maintain electrophysiological and ultrastructural remodeling that usually includes fibrosis. Interatrial conduction disturbances play a crucial role in the initiation of atrial fibrosis and in its associated complications. The diagnosis of interatrial blocks (IABs) is easy to perform using the surface ECG. IAB is classified as partial when the P wave duration is ≥120 ms, and advanced if the P wave also presents a biphasic pattern in II, III and aVF. IAB is very frequent in the elderly and, particularly in the case of the advanced type, is associated with AF, AF recurrences, stroke, and dementia. The anticoagulation in elderly patients at high risk of AF without documented arrhythmias is an open issue but recent data suggest that it might have a role, particularly in elderly patients with structural heart disease, high CHA2DS2VASc (Congestive heart failure/left ventricular dysfunction, Hypertension, Age ≥ 75 [doubled], Diabetes, Stroke [doubled] – Vascular disease, Age 65–74, and Sex category [female]), and advanced IAB. In this debate, we discuss the association of surface ECG IAB, a marker of atrial fibrosis, with AF and stroke. We also present the rationale that justifies further studies regarding anticoagulation in some of these patients.

Interatrial block and ischemic stroke

“…IAB has been described to predict occurrence of new onset and recurrent AF. A disturbed interatrial conduction, as in IAB, results in varying/shorter refractory periods and slower conduction velocities within the atrial myocardium-a potential substrate for the development of atrial arrythmias (5)(6)(7).…”

“…Anti-arrhythmic treatment of patients with aIAB has shown to reduce AF occurrence, however; no randomized data are available at the present time (6). Furthermore, IAB is highly prevalent in patients with embolic stroke (5,6,8,9). In patients with aIAB, due to a block of impulse propagation between the atria, depolarization follows a caudo-cranial route, first towards the AV node and then in a retrograde direction through the left atrium (3) (Figure 3), resulting in poor left atrial electromechanical function (6).…”

“…A poorly functioning left atrium predisposes to clot formation (6). It has been suggested that aIAB should be included in the risk assessment of patients with cryptogenic stroke even if no AF has been recorded (5). In this case, presence of aIAB warranted extended ambulatory ECG recording, which showed AF and anticoagulation treatment could be commenced.…”

Interatrial block

“…Исследования взаимосвязи межпредсердной блокады и эмболического инсульта привели к обсуждению возможности применения антикоагулянтов с целью профилактики инсульта у пациентов высокого тромбоэмболического риска с далеко зашедшей межпредсердной блокадой даже при отсутствии фибрилляции предсердий [47,51,52]. Кроме того, основанием для идеи применения антикоагулянтов у пациентов без…”

Bayés syndrome phenocopy in a patient with 1: 1 atrial flutter and corrected tetralogy of Fallot

“…Bayés syndrome is currently defined as the finding of advanced interatrial block (a-IAB) on 12-lead ECG associated with atrial fibrillation (AF) (1). Several studies have demonstrated the high risk of developing atrial fibrillation for patients with a-IAB, which has practical consequences of anticoagulant administration (2)(3)(4).…”