QUANTITATIVE-ANALYSIS OF T-WAVE ABNORMALITIES AND THEIR PROGNOSTIC IMPLICATIONS IN THE IDIOPATHIC LONG QT-SYNDROME

Objectives. We evaluated the diagnostic and prognostic value of morpho logic abnormalities of the T wave (mainly notched or biphasic T waves) in patients affected by the idiopathic long QT syndrome. Background. In the long QT syndrome, these abnormalities in T wave morphology are often observed and are of uncertain significance. Methods. The T wave abnormalities in the electrocardiogram (ECG) of 53 patients with the l ong QT syndrome and 53 control subjects of similar age and gender were analyzed, and their association with major cardiac events was defined . Results. Notched or biphasic T waves were defined according to morph ologic criteria. They were present in 33 (62%) of 53 patients with the long QT syndrome and in 8 (15%) of 53 control subjects (p < 0.001). M oreover, among patients with the long QT syndrome they were much more frequent in symptomatic (history of syncope or cardiac arrest) than in asymptomatic subjects (30 [81%] of 37 vs. 3 [19%] of 16, p < 0.001). The same distribution was observed within families with the long QT sy ndrome, in which symptomatic members had more pronounced T wave abnorm alities than did their asymptomatic siblings or parents. In symptomati c patients, the occurrence of T wave abnormalities was independent of the length of repolarization (corrected QT). These T wave abnormalitie s were associated with the presence of a specific pattern of abnormal left ventricular wall motion. Conclusions. This study has quantified a n ECG pattern typical of the long QT syndrome and provides the first e vidence that morphologic analysis of T wave abnormalities may contribu te to the diagnosis of the long QT syndrome and the identification of patients at higher risk for syncope or cardiac arrest.