Atrial electromechanical interval may predict cardioembolic stroke in apparently low risk patients with paroxysmal atrial fibrillation

Purpose: Considerable number of patients with atrial fibrillation (AF) develop cardioembolic stroke (CE) despite low CHADS2 score. We examined the possibility that use of the atrial electromechanical interval (AEMI) improves prediction of CE in patients with paroxysmal AF (PAF), particularly those with low CHADS2 score. Methods: We consecutively enrolled 122 patients with nonvalvular PAF (72±10 years, 83 men) and 52 healthy subjects as controls (70±6 years, 27 men). The PAF patients were divided into two groups depending on presence (n=43) or absence (n=79) of history of CE. Left atrial (LA) volume index (LAVI), peak myocardial velocity during late diastole (a') and AEMI (defined as time from onset of P-wave to onset of lateral a') were measured. Results: Patients with PAF had significantly larger LAVI (p 32 ml/m2 for LA volume index, 73 msec for AEMI. Using these thresholds, sensitivities and specificities of prediction of patients with PAF were 58% and 75% for LAVI, 49% and 75% for lateral a', 82% and 90% for AEMI, respectively. The sensitivity of AEMI for prediction of patients with PAF were significantly higher (p<0.05) than those of LAVI and lateral a'. Multivariate logistic regression analysis indicated that age (p<0.05), CHADS2 score (p<0.01), use of β-blockers (p<0.05), use of antiarrhythmic drugs (p<0.05), and AEMI (p<0.05), but not LAVI or a', were independently associated with history of CE in PAF patients. In PAF patients categorized into low risk by CHADS2 score (i.e.,CHADS2 score = 0 or 1, n=61), those with prolonged AEMI (≥82 msec) had significantly higher rates of CE than those with <82 msec (45% vs. 15%, p<0.05). Conclusions: As compared with echocardiographic parameters of LA size and LA function, AEMI appears to be more useful for identifying PAF patients. AEMI may enable to detect high risk PAF patients, especially those categorized into low risk by CHADS2 score.