***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background —Experimental studies suggest that the interval between peak and end of T wave ( Tpe ) in transmural ECGs reflects transmural dispersion of repolarization ( TDR ) , which is amplified by & bgr;-adrenergic stimulation in the LQT1 model . In 82 patients with genetically identified long-QT syndrome ( LQTS ) and 33 control subjects , we examined T-wave morphology and various parameters for repolarization in 12-lead ECGs including corrected QT ( QTc ; QT/R-R1/2 ) and corrected Tpe ( Tpec ; Tpe/R-R1/2 ) before and during exercise stress tests . Methods and Results —Under baseline conditions , LQT1 ( n=51 ) showed 3 cardinal T-wave patterns ( broad-based , normal-appearing , late-onset ) and LQT2 ( n=31 ) 3 patterns ( broad-based , bifid with a small or large notch ) . The QTc and Tpec were 510±68 ms and 143±53 ms in LQT1 and 520±61 ms and 195±69 ms in LQT2 , respectively , which were both significantly larger than those in control subjects ( 402±36 ms and 99±36 ms ) . Both QTc and Tpec were significantly prolonged during exercise in LQT1 ( 599±54 ms and 215±46 ms ) with morphological change into a broad-based T-wave pattern . In contrast , exercise produced a prominent notch on the descending limb of the T wave , with no significant changes in the QTc and Tpec ( 502±82 ms and 163±86 ms : n=19 ) in LQT2 . Conclusions —Tpe interval increases during exercise in LQT1 but not in LQT2 , which may partially account for the finding that fatal cardiac events in LQT1 are more often associated with exercise AIMS To evaluate the prognostic value of the QT interval and QT interval dispersion in total and in cardiovascular mortality , as well as in cardiac morbidity , in a general population . METHODS AND RESULTS The  QT interval  was measured in all leads from a st and ard 12-lead ECG in a r and om sample of 1658 women and 1797 men aged 30 - 60 years . QT interval dispersion was calculated from the maximal difference between QT intervals in any two leads . All cause mortality over 13 years , and cardiovascular mortality as well as cardiac morbidity over 11 years , were the main outcome parameters . Subjects with a prolonged QT interval ( 430 ms or more ) or prolonged QT interval dispersion ( 80 ms or more ) were at higher risk of cardiovascular death and cardiac morbidity than subjects whose QT interval was less than 360 ms , or whose QT interval dispersion was less than 30 ms . Cardiovascular death relative risk ratios , adjusted for age , gender , myocardial infa rct , angina pectoris , diabetes mellitus , arterial hypertension , smoking habits , serum cholesterol level , and heart rate were 2.9 for the QT interval ( 95 % confidence interval 1.1 - 7.8 ) and 4.4 for QT interval dispersion ( 95 % confidence interval 1.0 - 19 - 1 ) . Fatal and non-fatal cardiac morbidity relative risk ratios were similar , at 2.7 ( 95 % confidence interval 1.4 - 5.5 ) for the QT interval and 2.2 ( 95 % confidence interval 1.1 - 4.0 ) for QT interval dispersion . CONCLUSION Prolongation of the QT interval and QT interval dispersion independently affected the prognosis of cardiovascular mortality and cardiac fatal and non-fatal morbidity in a general population over 11 years 
    Output:
    
This meta- analysis showed that Tpeak-Tend interval is significant higher in individuals who are at elevated risk of adverse events in congenital LQTS , offering incremental value for risk stratification