Ischemic heart disease was associated with prolonged 24-hour mean QTo (461 ms vs 426 ms, P<0.01) and abnormal rate dependence compared to healthy subjects, worsening with higher NYHA class.
Observational
Do repolarization characteristics (QT/RR relationship) differ between patients with ischemic heart disease and healthy subjects, and do they correlate with symptom severity?
Patients with ischemic heart disease and heart failure exhibit progressive abnormalities in repolarization characteristics that correlate with symptom severity, suggesting a mechanism for increased sudden death risk.
Tasa de eventos absoluta: 461% vs 426%
valor p: p=<0.01
BACKGROUND: Congestive heart failure is a common condition with high mortality. Many of these deaths are sudden and unexpected. Ventricular action potential, surface repolarization (QT interval), and dispersion of repolarization are prolonged in the failing heart, contributing to arrhythmogenesis and sudden death. We studied the relationship between QT and heart rate (RR interval) from ambulatory recordings using a novel method in patients with ischemic heart disease and varying degrees of left-ventricular impairment (IHD) and compared them to healthy subjects (HS). We compare the degree of abnormality with the functional impairment and ejection fraction. METHODS: Using a previously described automated method for continuous estimation of the QT/RR characteristic that incorporates a correction formula for compensation of QT adaptation lag (VERDA, Del Mar Reynolds Medical Ltd., Hertford, UK), we compared recordings from 41 IHD patients with age-matched HS. RESULTS: IHD Patients have prolonged 24-hour mean QTo (461 ms vs 426 ms, P < 0.01), and abnormal rate dependence relative to controls (24-hour mean slope: 0.20 vs 0.14, P < 0.001; J: 0.38 vs 0.28, P < 0.001). There is increased temporal variation in J with respect to HS. These abnormalities of repolarization increase with worsening NYHA class, but do not correlate with ejection fraction. CONCLUSIONS: The use of a universal correction formula to compare dynamic QT data in IHD patients is inappropriate. The observed progressive abnormalities may be responsible for the high incidence of sudden death through promotion of arrhythmias.
Lang et al. (Thu,) conducted a observational in Ischemic heart disease and heart failure. Ischemic heart disease vs. Healthy subjects was evaluated on 24-hour mean QTo (p=<0.01). Ischemic heart disease was associated with prolonged 24-hour mean QTo (461 ms vs 426 ms, P<0.01) and abnormal rate dependence compared to healthy subjects, worsening with higher NYHA class.
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