BACKGROUND: Current relevance of T-wave alternans is based on its association with electrical disorder and elevated cardiac risk. Quantitative reports would improve understanding on TWA augmentation mechanisms during mental stress or prior to tachyarrhythmias. However, little information is available about quantitative TWA values in clinical populations. This study aims to create and compare TWA profiles of healthy subjects and ICD patients, evaluated on treadmill stress protocols. METHODS: Apparently healthy subjects, not in use of any medication were recruited. All eligible ICD patients were capable of performing an attenuated stress test. TWA analysis was performed during a 15-lead treadmill test. The derived comparative profile consisted of TWA amplitude and its associated heart rate, at rest (baseline) and at peak TWA value. Chi-square or Mann-Whitney tests were used with p values < or = 0.05. Discriminatory performance was evaluated by a binary logistic regression model. RESULTS: 31 healthy subjects (8F, 23M) and 32 ICD patients (10F, 22M) were different on baseline TWA (1 +/- 2 microV; 8 +/- 9 muV; p < 0.001) and peak TWA values (26 +/- 13 microV; 37 +/- 20 microV; p = 0,009) as well as on baseline TWA heart rate (79 +/- 10 bpm; 67 +/- 15 bpm; p < 0.001) and peak TWA heart rate (118 +/- 8 bpm; 90 +/- 17 bpm; p < 0.001). The logistic model yielded sensitivity and specificity values of 88.9% and 92.9%, respectively. CONCLUSIONS: Healthy subjects and ICD patients have distinct TWA profiles. The new TWA profile representation (in amplitude-heart rate pairs) may help comparison among different research protocols.
BACKGROUND: Current relevance of T-wave alternans is based on its association with electrical disorder and elevated cardiac risk. Quantitative reports would improve understanding on TWA augmentation mechanisms during mental stress or prior to tachyarrhythmias. However, little information is available about quantitative TWA values in clinical populations. This study aims to create and compare TWA profiles of healthy subjects and ICDpatients, evaluated on treadmill stress protocols. METHODS: Apparently healthy subjects, not in use of any medication were recruited. All eligible ICDpatients were capable of performing an attenuated stress test. TWA analysis was performed during a 15-lead treadmill test. The derived comparative profile consisted of TWA amplitude and its associated heart rate, at rest (baseline) and at peak TWA value. Chi-square or Mann-Whitney tests were used with p values < or = 0.05. Discriminatory performance was evaluated by a binary logistic regression model. RESULTS: 31 healthy subjects (8F, 23M) and 32 ICDpatients (10F, 22M) were different on baseline TWA (1 +/- 2 microV; 8 +/- 9 muV; p < 0.001) and peak TWA values (26 +/- 13 microV; 37 +/- 20 microV; p = 0,009) as well as on baseline TWA heart rate (79 +/- 10 bpm; 67 +/- 15 bpm; p < 0.001) and peak TWA heart rate (118 +/- 8 bpm; 90 +/- 17 bpm; p < 0.001). The logistic model yielded sensitivity and specificity values of 88.9% and 92.9%, respectively. CONCLUSIONS: Healthy subjects and ICDpatients have distinct TWA profiles. The new TWA profile representation (in amplitude-heart rate pairs) may help comparison among different research protocols.
Authors: N A Estes; G Michaud; D P Zipes; N El-Sherif; F J Venditti; D S Rosenbaum; P Albrecht; P J Wang; R J Cohen Journal: Am J Cardiol Date: 1997-11-15 Impact factor: 2.778
Authors: Daniel M Bloomfield; Richard C Steinman; Pearila B Namerow; Michael Parides; Jorge Davidenko; Elizabeth S Kaufman; Timothy Shinn; Anne Curtis; John Fontaine; Douglas Holmes; Andrea Russo; Chuen Tang; J Thomas Bigger Journal: Circulation Date: 2004-09-27 Impact factor: 29.690
Authors: Tuomo Nieminen; Terho Lehtimäki; Jari Viik; Rami Lehtinen; Kjell Nikus; Tiit Kööbi; Kari Niemelä; Väinö Turjanmaa; Willi Kaiser; Heini Huhtala; Richard L Verrier; Heikki Huikuri; Mika Kähönen Journal: Eur Heart J Date: 2007-07-25 Impact factor: 29.983