BACKGROUND: Although the hallmark of long-QT syndrome (LQTS) is abnormal cardiac repolarization, there are varying degrees of phenotypic expression and arrhythmic risk. Our aim was to evaluate the performance of a morphological T-wave analysis program in defining breakthrough LQTS arrhythmic risk beyond the QTc value. METHODS AND RESULTS: We analyzed 407 genetically confirmed patients with LQT1 (n=246; 43% men) and LQT2 (n=161; 41% men) over the mean follow-up period of 6.4±3.9 years. ECG analysis was conducted using a novel, proprietary T-wave analysis program. Time to a LQTS-associated cardiac event was analyzed using Cox proportional hazards regression methods. Twenty-three patients experienced ≥1 defined breakthrough cardiac arrhythmic events with 5- and 10-year event rates of 4% and 7%. Two independent predictors of future LQTS-associated cardiac events from the surface ECG were identified: left slope of T wave in lead V6 (hazard ratio=0.40 [0.24-0.69]; P<0.001) and T-wave center of gravity x axis (last 25% of wave) in lead I (hazard ratio=1.90 [1.21-2.99]; P=0.005), C statistic of 0.77 (0.65-0.89). When added to the QTc (C statistic 0.68 for QTc alone), discrimination improved to 0.78. Genotype analysis showed weaker association between these T-wave variables and LQT1-triggered events while these features were stronger in patients with LQT2 and significantly outperformed the QTc (C statistic, 0.82 [0.71-0.93]). CONCLUSION: Detailed morphological analysis of the T wave provides novel insights into risk of breakthrough arrhythmic events in LQTS, particularly LQT2. This observation has the potential to guide clinical decision making and further refine risk stratification.

• MeSH
• akční potenciály MeSH
• antiarytmika terapeutické užití   MeSH
• časové faktory MeSH
• dítě MeSH
• dospělí MeSH
• elektrokardiografie * MeSH
• fenotyp MeSH
• genetická predispozice k nemoci MeSH
• hodnocení rizik MeSH
• Kaplanův-Meierův odhad MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• prediktivní hodnota testů MeSH
• převodní systém srdeční účinky léků   patofyziologie   MeSH
• proporcionální rizikové modely MeSH
• rizikové faktory MeSH
• Romanův-Wardův syndrom diagnóza   farmakoterapie   genetika   patofyziologie   MeSH
• rozdělení chí kvadrát MeSH
• srdeční frekvence účinky léků   MeSH
• syndrom dlouhého QT diagnóza   farmakoterapie   genetika   patofyziologie   MeSH
• výsledek terapie MeSH
• Check Tag
• dítě MeSH
• dospělí MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

BACKGROUND: Prolongation of the QT on the surface electrocardiogram can be due to either genetic or acquired causes. Distinguishing congenital long QT syndrome (LQTS) from acquired QT prolongation has important prognostic and management implications. We aimed to investigate if quantitative T-wave analysis could provide a tool for the physician to differentiate between congenital and acquired QT prolongation. METHODS: Patients were identified through an institution-wide computer-based QT screening system which alerts the physician if the QTc ≥ 500 ms. ECGs were retrospectively analyzed with an automated T-wave analysis program. Congenital LQTS was compared in a 1:3 ratio to those with an identified acquired etiology for QT prolongation (electrolyte abnormality and/or prescription of known QT prolongation medications). Linear discriminant analysis was performed using 10-fold cross-validation to statistically test the selected features. RESULTS: The 12-lead ECG of 38 patients with congenital LQTS and 114 patients with drug-induced and/or electrolyte-mediated QT prolongation were analyzed. In lead V5 , patients with acquired QT prolongation had a shallower T wave right slope (-2,322 vs. -3,593 mV/s), greater T-peak-Tend interval (109 vs. 92 ms), and smaller T wave center of gravity on the x axis (290 ms vs. 310 ms; p < .001). These features could distinguish congenital from acquired causes in 77% of cases (sensitivity 90%, specificity 58%). CONCLUSION: T-wave morphological analysis on lead V5 of the surface ECG could successfully differentiate congenital from acquired causes of QT prolongation.

• MeSH
• diferenciální diagnóza MeSH
• elektrokardiografie metody   MeSH
• lidé MeSH
• mladiství MeSH
• retrospektivní studie MeSH
• senioři MeSH
• senzitivita a specificita MeSH
• syndrom dlouhého QT vrozené   diagnóza   patofyziologie   MeSH
• Check Tag
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

BACKGROUND: Coronary microvascular dysfunction (CMD) is linked to adverse cardiovascular events. Definitive diagnosis of CMD requires invasive provocative testing during angiography. We developed and tested a novel computerized T wave analysis tool to identify electrocardiographic signatures of CMD. METHODS: 1552 patients underwent an invasive assessment of coronary microvascular function. Patients with interpretable pre-procedural ECGs were divided into 2 age and sex matched groups (n=261 in each group, 75% female): normal microvascular function, CFR>2.5 (CFR+), and abnormal microvascular function, CFR ≤ 2.5 (CFR-). ECGs were evaluated using a novel T wave program that quantified subtle changes in T wave morphology. RESULTS: T wave repolarization parameters were significantly different between patients with normal and abnormal microvascular function. The top 3 features in males comprised of T wave area in V6 (CFR+: 10091.4 mV(2) vs. CFR-: 8152.3 mV(2), p<0.05); T1 Y-center of gravity in lead II (CFR+: 17.8 mV vs. CFR-: 22.4, p<0.005) and T Peak-T End in lead II (CFR+: 97.6 msec vs. CFR-: 91.1 msec, p<0.05). These could identify the presence of an abnormal CFR with 74 ± 0.2% accuracy. In females, the top 3 features were T wave right slope lead V6 (CFR+: -2489.1 mV/msec vs. CFR-: -2352.3 mV/msec, p<0.005); Amplitude in V6 (CFR+: 190.4 mV vs. 172.7 mV, p=0.05) and Y-center of gravity in lead V1 (CFR+: 33.3 vs. CFR-: 40.0, p=0.001). These features could identify the presence of an abnormal CFR with 67 ± 0.3% accuracy. CONCLUSION: Our data demonstrates that a computer-based repolarization measurement tool may identify electrocardiographic signatures of CMD.

• MeSH
• automatizované zpracování dat metody   MeSH
• elektrokardiografie metody   MeSH
• intervenční ultrasonografie MeSH
• koronární angiografie MeSH
• koronární cévy patofyziologie   MeSH
• koronární cirkulace fyziologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mikrocirkulace fyziologie   MeSH
• následné studie MeSH
• nemoci koronárních tepen diagnóza   patofyziologie   MeSH
• reprodukovatelnost výsledků MeSH
• retrospektivní studie MeSH
• rychlost toku krve MeSH
• software * MeSH
• stupeň závažnosti nemoci MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH

BACKGROUND: Congenital long QT syndrome (LQTS) is characterized by QT prolongation. However, the QT interval itself is insufficient for diagnosis, unless the corrected QT interval is repeatedly ≥500 ms without an acquired explanation. Further, the majority of LQTS patients have a corrected QT interval below this threshold, and a significant minority has normal resting corrected QT interval values. Here, we aimed to develop and validate a novel, quantitative T wave morphological analysis program to differentiate LQTS patients from healthy controls. METHODS AND RESULTS: We analyzed a genotyped cohort of 420 patients (22±16 years, 43% male) with either LQT1 (61%) or LQT2 (39%). ECG analysis was conducted using a novel, proprietary T wave analysis program that quantitates subtle changes in T wave morphology. The top 3 discriminating features in each ECG lead were determined and the lead with the best discrimination selected. Classification was performed using a linear discriminant classifier and validated on an untouched cohort. The top 3 features were Tpeak-Tend interval, T wave left slope, and T wave center of gravity x axis (last 25% of the T wave). Lead V6 had the best discrimination. It could distinguish 86.8% of LQTS patients from healthy controls. Moreover, it distinguished 83.33% of patients with concealed LQTS from controls, despite having essentially identical resting corrected QT interval values. CONCLUSIONS: T wave quantitative analysis on the 12-lead surface ECG provides an effective, novel tool to distinguish patients with either LQT1/LQT2 from healthy matched controls. It can provide guidance while mutation-specific genetic testing is in motion for family members.

• MeSH
• elektrokardiografie metody   MeSH
• genotyp MeSH
• lidé MeSH
• mladý dospělý MeSH
• počítačové zpracování signálu MeSH
• senzitivita a specificita MeSH
• syndrom dlouhého QT klasifikace   diagnóza   genetika   MeSH
• Check Tag
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

INTRODUCTION: Initiation of class III anti-arrhythmic medications requires telemetric monitoring for ventricular arrhythmias and QT prolongation to reduce the risk of torsades de pointes (TdP). Heart rate-corrected QT interval (QTc) is an indicator of risk, however it is imperfect, and subtle abnormalities of repolarization have been linked with arrhythmogenesis. PURPOSE: Identification of electrocardiographic predictors of torsadogenic risk through the application of a novel T wave analysis tool. METHODS: Among all patients admitted to Mayo Clinic for initiation of dofetilide or sotalol, we identified 13 cases who developed drug-induced TdP and 26 age and sex matched controls that did not develop TdP. The immediate pre-TdP ECG of those with TdP was compared to the last ECG performed prior to hospital discharge in controls using a novel T wave program that quantified subtle changes in T wave morphology. RESULTS: The QTc and 12 T wave parameters successfully distinguished TdP cases from controls. The top performing parameters were the QTc in lead V3 (mean case vs control 480 vs 420 msec, p < 0.001, r = 0.72) and T wave right slope in lead I (mean case vs control -840.29 vs -1668.71 mV/s, p = 0.002, r = 0.45). The addition of T wave right slope to QTc improved prediction accuracy from 79 to 88 %. CONCLUSION: Our data demonstrate that, in addition to QTc, the T wave right slope is correlated strongly with TdP risk. This suggests that a computer-based repolarization measurement tool that integrates additional data beyond the QTc may identify patients with the greatest torsadogenic potential.

• MeSH
• antiarytmika škodlivé účinky   MeSH
• elektrokardiografie metody   MeSH
• fenethylaminy škodlivé účinky   MeSH
• lidé středního věku MeSH
• lidé MeSH
• prediktivní hodnota testů * MeSH
• senioři MeSH
• software * MeSH
• sotalol škodlivé účinky   MeSH
• studie případů a kontrol MeSH
• sulfonamidy škodlivé účinky   MeSH
• torsades de pointes chemicky indukované   prevence a kontrola   MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH