Usefulness of QT-interval parameters for cardiovascular risk stratification in type 2 diabetic patients with arterial hypertension

Abstract

QT-interval parameters are potential indicators of increased cardiovascular risk. We evaluated prospectively their prognostic value, in relation to other risk markers, for cardiovascular fatal and nonfatal events in a cohort of 271 hypertensive type 2 diabetic outpatients. QT intervals were measured from 12-lead standard ECGs obtained on admission and maximum rate-corrected QTinterval duration and QT-interval dispersion (QTd) calculated. Clinical and laboratory data and 2-D echocardiograms (available in 126 patients) were recorded. Survival analyses included Kaplan-Meier survival curves, uni and multivariate Cox proportional-hazards models. After a median follow-up of 55 months (range 2-84), 68 total fatal or nonfatal cardiovascular events and 34 cardiovascular deaths (24 of them from cardiac causes) were observed. In multivariate Cox analysis, QTd was an independent predictor for total cardiovascular events (HR: 1.16, 95% CI: 1.01-1.34, for each 10 ms increments) and for cardiac deaths (HR: 1.28, 95% CI: 1.01-1.60). Other independent risk indicators for cardiovascular morbidity and mortality were echocardiographic left ventricular hypertrophy (Echo-LVH), serum triglycerides, presence of pre-existing cardiac and peripheral arterial disease, age, diabetes duration, heart rate and the presence of frequent ventricular premature contractions on ECG. The combination of QTd and Echo-LVH improved cardiovascular risk stratification compared with either alone, the presence of both prolonged QTd (465 ms) and Echo-LVH was associated with a 3.2-fold (95% CI: 1.7-6.1) increased risk of a first cardiovascular event and a 5.9-fold (95% CI: 2.1-16.4) increased risk of cardiovascular death. Thus, QT provided additive prognostic information for cardiovascular morbidity and mortality beyond that obtained from conventional risk markers, including Echo-LVH, in type 2 diabetic patients with arterial hypertension.

Spironolactone for poorly controlled hypertension in type 2 diabetes: conflicting effects on blood pressure, endothelial function, glycaemic control and hormonal profiles

“…Also, a prolonged QTc interval is thought to provide additional prognostic information for cardiovascular morbidity and mortality rates beyond that obtained from conventional risk markers in type 2 diabetic patients with hypertension [29]. Spironolactone therapy, in our study, resulted in a significant reduction in QTc intervals compared with placebo.…”

Electrocardiographic Findings in Systemic Lupus Erythematosus: Data From an International Inception Cohort

“…Increased QTd is another indicator of myocardial electrical instability that has been associated with arrhythmias and cardiac death (18). In general medical populations, QTd is an independent predictor of cardiovascular mortality (hazard ratio 1.28 [95% CI 1.01, 1.60] per each 10-msec increase in QTd) (19). In patients with rheumatic diseases, a 50-msec increase in the QTc interval has been associated with a doubling of the relative hazard for all-cause mortality, and some authors have suggested a connection between disease activity and arrhythmogenesis (20).…”

Combined QT Interval and Voltage Criteria Improve Left Ventricular Hypertrophy Detection in Resistant Hypertension

“…Also, experimentally, regression of LVH normalizes LVH-induced proarrhythmic repolarization abnormalities, 28,30 whereas reduction in LVM and regression of electrocardiographic LVH indexes are associated with QT interval shortening. 31 Finally, it was demonstrated recently that QT parameters are predictors of cardiovascular mortality in hypertensive patients with electrocardiographic LVH 10 and with type 2 diabetes, 11 as it was already known for electrocardiographic indexes of LVH. 32,33 Therefore, it appears reasonable to speculate that QT interval parameters and ECG voltage indexes could act in combination not only to determine an increased chance of having echocardiographic LVH, but also to identify a subgroup of hypertensive patients with a high cardiovascular risk profile, particularly for sudden arrhythmic death.…”

“…Moreover, it has been reported recently that they probably constitute true cardiovascular mortality markers in hypertensive patients. 10,11 As far as we know, no study has evaluated QT interval parameters in patients with RH, a common but generally understudied subgroup of hypertensive patients.Therefore, the objective of this study was to assess the relationships between various QT interval-derived parameters and echocardiographic LVH in a large group of RH patients and, particularly, to evaluate whether any QT parameter can provide additive information for LVH detection beyond that obtained from the best ECG voltage criterion. …”

“…Moreover, it has been reported recently that they probably constitute true cardiovascular mortality markers in hypertensive patients. 10,11 As far as we know, no study has evaluated QT interval parameters in patients with RH, a common but generally understudied subgroup of hypertensive patients.…”