Possible triggering of paroxysmal atrial fibrillation in normal hearts by psychological stressors: a report of two cases. Paroxysmal atrial fibrillation was triggered by psychological stress in two patients, both of whom had normal echocardiograms and coronary angiography. Neither patient was alcoholic or had ingested ethanol in relation to the onset of atrial fibrillation and both were free of metabolic derangements. Possible mechanisms involved in the triggering of atrial fibrillation are discussed. 