Potential Clinical Correlates and Risk Factors for Interatrial Block

Abstract

Background: Interatrial block (IAB; P wave ≧110 ms) denotes a conduction delay between the atria, is strongly associated with atrial tachyarrhythmias, left atrial enlargement, left atrial electromechanical dysfunction, and is a risk for embolism. Despite this, potential risk factors for IAB have not been clearly defined. Methods: Patients admitted via the Emergency Department for nonacute medical reasons to the nontelemetry general medical floors of a tertiary care general hospital from October to November 2004 were screened for sinus rhythm on electrocardiograms. Four hundred and four patients who met our criteria were then evaluated for IAB on respective electrocardiograms. All patients were subsequently compared for common diseases as well as coronary artery disease (CAD) risk factors and divided into two groups, those with IAB and those without (control). Mean age ± standard deviation, odds ratios (ORs), 95% confidence intervals (CIs), r values, and p values were calculated. p values <0.05 were considered statistically significant. Results: From the sample (n = 404), 182 patients had IAB (45%; mean age 64.32 ± 19.27 years; males 51.6%) while 222 did not (control). CAD (OR 3.150, 95% CI 2.05–4.83; p < 0.001, r = 0.3), hypertension (OR 2.918, 95% CI 1.85–4.60; p < 0.001, r = 0.2), diabetes mellitus (OR 2.542, 95% CI 1.62–3.97; p < 0.001, r = 0.1), and hypercholesterolemia (OR 1.823, 95% CI 1.22–2.74; p = 0.004, r = 0.2) were significant risk factors and correlates for IAB. Multivariate analysis using stepwise linear regression revealed these factors as direct correlates of IAB. Conclusion: CAD, hypertension, diabetes mellitus and hypercholesterolemia appear to be risk factors for IAB in general hospital patients admitted for nonacute reasons. Considering the known sequelae of IAB, awareness of its associations with such risk factors could be important for patient risk stratification.

Prospective evaluation of atrial tachyarrhythmias in patients with interatrial block

“…We had previously demonstrated that coronary artery disease and its perennial risk factors such as hypertension, diabetes mellitus and hypercholesterolemia could be potential risk factors for developing of interatrial block [12]. These comorbidities presumably exert their deleterious effects by encumbering the Bachmann Bundle (the principal interatrial pathway) either directly, by altering atrial properties or indirectly, via ischemia of its vascular supply (sinoatrial nodal artery and its branches).…”

“…Atrial fibrillation (16) No atrial fibrillation (69) that prolongation of interatrial conduction is thought to be the main operative mechanism in atrial fibrillation, either risk factor, if not both, could have a multifarious relationship with interatrial block or its sequelae [12,13]. Indeed, hypertension, be it alone or in concert with interatrial block, could also trigger remodeling of the left atrial and potentiate its subsequent dysfunction, further contributing to the vicious cycle that increases the risk of atrial fibrillation [2,3,12].…”

“…Indeed, hypertension, be it alone or in concert with interatrial block, could also trigger remodeling of the left atrial and potentiate its subsequent dysfunction, further contributing to the vicious cycle that increases the risk of atrial fibrillation [2,3,12]. Results from the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study in which 4060 patients with recurrent atrial fibrillation aged ≥ 65 years were randomized to medical management via rhythm control (restoration and/or maintenance of sinus rhythm attempted) versus rate control (restoration and/or maintenance of sinus rhythm not attempted) strategies, have indeed indicated that a strategy of rate control among atrial fibrillation patients could be a desirable pursuit and at least, be as effective as efforts of rhythm control [8].…”

Exercise-Induced Improvement in Atrial Depolarization Abnormality in a Patient after Treatment with Beta-Adrenergic Blockers

“…Established cardiovascular risk factors such as hypertension, hyperlipidemia and diabetes mellitus are frequently prevalent in patients with partial and advanced IAB [2, 11]. It is not surprising therefore that myocardial ischemia has been implicated as a potential cause for worsening interatrial conduction [12].…”

Limited utility of interatrial block in predicting ischemia on coronary angiography in patients with suboptimal exercise performance

“…The principal pathophysiology is quite likely centered around an ischemic focus pertaining the Bachmann Bundle, where impairment of its vascular supply (thought to be mainly the sinoatrial nodal artery and its branches) could be a leading cause. Indeed, we had previously delineated the potential association of interatrial block with underlying coronary artery disease, hypertension, diabetes mellitus and hypercholesterolemia, all potent harbingers of atherosclerosis [4]. More importantly, increase in P-wave durations has also been shown to occur with cardiac ischemia [5][6][7], particularly in patients with coronary artery disease who undergo exercise tolerance [5,8].…”