Simoncelli U, Marchetti A, Sorgato A, Rusconi C. Minerva Cardioangiol 1991 Jun;39(6):219-25. Twenty-three consecutive subjects (age 46.7 +/- 21, range 13-78) addressed to our attention for symptoms attributed to documented or suspected supra ventricular arrhythmias underwent transesophageal electrophysiologic study. On the basis of the preliminary investigations 15 proved free from organic heart disease, 2 were affected with ischemic heart disease (secondary angina), 6 with hypertensive cardiomyopathy. In each patient the sensibility, specificity and positive predictive value of the following reports regarding the occurrence of paroxysmal fibrillation and flutter (Ffap) were evaluated: a) echo reports of left atrial enlargement; b) ECG signs of atrial enlargement; c) interatrial conduction time (TCIA) assessed with unipolar transesophageal recording. As TCIA we adopted the time interval intercurrent from the first low-voltage deflection of the esophageal P wave (far field) and the apex of the intrinsecoid deflection of the same wave. TCIA proved significantly longer in the 12 patients affected with Ffap compared with those free from documented paroxysmal or inducible arrhythmias or affected with paroxysmal junctional reciprocating tachycardias: 76.6 +/- 11 vs 51.8 +/- 11.7; p less than 0.001. A TCIA greater than 63 msec characterizes with satisfactory sensibility and specificity the occurrence of Ffap: sens. 75%, spec. 91%, positive predictive value 90%. Echo and ECG reports of atrial enlargement behave as highly specific but not sufficiently sensitive indexes of the occurrence of Ffap: sens. 42%, spec. 100%, pos. pred. val. 100% and sens. 17%, spec. 100%, pos.pred.val. 100% resp. We concluded that TCIA is an index correlated with and predictive of the occurrence of Ffap in patients symptomatic for cardiopalmus or neurologic symptoms in the absence of other arrhythmias detectable with Holter monitoring which are able to produce clinical symptoms.