F-AMPLITUDE, LEFT ATRIAL APPENDAGE VELOCITY, AND THROMBOEMBOLIC RISK IN NONRHEUMATIC ATRIAL-FIBRILLATION

Background: Reduced left atrial appendage velocity (LAAV) has been ide ntified as a marker for thromboembolism in patients with atrial fibril lation. Hypothesis: It was postulated that electrocardiographic (ECG) F-wave amplitude would correlate with LAAV, and inversely with the ris k of thromboembolism in patients with atrial fibrillation. Methods: In all, 53 patients with nonrheumatic (NRAF) and 7 patients with rheumat ic (RAF) atrial fibrillation underwent assessment of maximum LAAV, whi ch was correlated to the maximum ECG F-wave voltage from lead V-1 (Fma x). In 450 NRAF patients on neither aspirin nor warfarin, the relation ship between Fmax and thromboembolic risk was assessed over an average follow-up of 1.3 years. Results: Fmax did not correlate with LAAV (r = 0.2, p = 0.07). Patients with intermittent atrial fibrillation (n = 123) had smaller Fmax amplitude than patients with constant atrial fib rillation (n = 327) (mean 0.73 vs. 0.88 mV(-1), p = 0.001). Fmax ampli tude was not related to a history of hypertension, systolic blood pres sure, duration of NRAF, abnormal transthoracic echocardiographic left ventricular (LV) systolic function or left atrial (LA) diameter There was a strong trend for increased LV mass being related to smaller Fmax amplitude after adjusting for body surface area (p = 0.06). Fmax ampl itude was not correlated with risk of embolic events, including only t hose events presumed by a panel of case-blinded neurologists to be car dioembolic. Conclusion: Fmax amplitude in NRAF is smaller in patients with intermittent versus constant AF. It does not correlate with LAAV, LA size, increased LV mass, or systolic dysfunction, hypertension, or risk of embolism. Therefore, Fmax amplitude may not be used as a surr ogate for LAAV, or as a measure of thromboembolic risk in NRAF.