Interatrial blocks. A separate entity from left atrial enlargement: a consensus report.

Impaired interatrial conduction or interatrial block is well documented but is not described as an individual electrocardiographic (ECG) pattern in most of ECG books, although the term atrial abnormalities to encompass both concepts, left atrial enlargement (LAE) and interatrial block, has been coined. In fact, LAE and interatrial block are often associated, similarly to what happens with ventricular enlargement and ventricular block. The interatrial blocks, that is, the presence of delay of conduction between the right and left atria, are the most frequent atrial blocks. These may be of first degree (P-wave duration >120 milliseconds), third degree (longer P wave with biphasic [±] morphology in inferior leads), and second degree when these patterns appear transiently in the same ECG recording (atrial aberrancy). There are evidences that these electrocardiographic P-wave patterns are due to a block because they may (a) appear transiently, (b) be without associated atrial enlargement, and (c) may be reproduced experimentally. The presence of interatrial blocks may be seen in the absence of atrial enlargement but often are present in case of LAE. The most important clinical implications of interatrial block are the following: (a) the first degree interatrial blocks are very common, and their relation with atrial fibrillation and an increased risk for global and cardiovascular mortality has been demonstrated; (b) the third degree interatrial blocks are less frequent but are strong markers of LAE and paroxysmal supraventricular tachyarrhythmias. Their presence has been considered a true arrhythmological syndrome.

Prediction of paroxysmal atrial fibrillation after aortic valve replacement in patients with aortic stenosis: identification of potential risk factors.

BACKGROUND AND AIM OF THE STUDY: Paroxysmal atrial fibrillation (AF) is a frequent complication after cardiac surgery. The study aim was to identify preoperative predictors of risk for this condition in patients with aortic stenosis after aortic valve replacement. METHODS: The influence of clinical, echocardiographic and 24 h electrocardiogram (ECG) parameters on episodes of paroxysmal AF after aortic valve replacement (AVR) in 423 patients (156 women, 267 men; mean age 58 +/- 10 years) with aortic stenosis was analyzed. Episodes of postoperative paroxysmal AF were noted in 120 patients (28%). RESULTS: Univariate analyses identified the following variables as risk factors for arrhythmia: age, NYHA functional class, history of preoperative paroxysmal AF, left ventricular mass index, >300 supraventricular beats on 24h ECG before surgery, presence of supraventricular tachycardia (SVT), SVT of >5 beats or with a rate >120 beats/min. Concomitant coronary artery bypass (CABG) grafting and presence of enlarged left atrium had no impact. By multivariate analysis, four variables were identified as independent predictors: age (odds ratio 1.7; 95% CI 1.2-2.1); history of paroxysmal AF (OR 3.2; CI 1.4-7.3); presence of >300 supraventricular beats/24 h (OR 1.9; CI 1.1-3.4); and presence of SVT (OR 2.1; CI 1.3-3.4). Discriminatory analysis revealed that a model comprising these four parameters enabled risk prediction in 68% of patients. CONCLUSION: In patients with isolated aortic stenosis, age, past history of paroxysmal AF episodes, >300 supraventricular beats/24 h and presence of SVT during 24 h before AVR were predictors of postoperative paroxysmal AF episodes. Left atrial diameter and simultaneous CABG during AVR did not influence the likelihood of postoperative paroxysmal AF.