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

Abstract

Abstract-QT interval parameters have been associated with left ventricular hypertrophy (LVH) in hypertensive patients.The aim of this study is to assess this relationship in resistant hypertension and, in particular, to evaluate whether any QT interval parameter could provide additive information for LVH beyond that obtained from the best electrocardiographic voltage criterion. In a cross-sectional study, 471 resistant hypertensives were submitted to standard 12-lead ECGs, 24-hour ambulatory blood pressure monitoring, and 2D echocardiographic examinations. QT interval durations and QRS voltages were measured, and maximum rate-corrected QT interval duration (QTc max ) and dispersion (QTd), and Sokolow's and Cornell's voltage product were calculated. Statistical analyses involved bivariate tests and multivariate logistic regression, with LVH as the dependent variable. A total of 383 patients (81%) had echocardiographic LVH. In bivariate comparisons, both QT interval parameters showed a predictive performance for LVH similar to Cornell's product, the best ECG voltage criterion. In multivariate analysis, QT parameters and Cornell's product were independently associated with LVH, after adjustment for other LVH determinants. QTc interval Ͼ440 ms 1/2 and dispersion Ͼ60 ms were associated with a 2-fold (95% confidence interval [CI], 1.1 to 3.8) greater chance of having LVH, whereas Cornell's product Ͼ240 mV⅐ms implied a 2.6-fold (95% CI, 1.2 to 6.1) increased chance of LVH. The combination of prolonged QT interval and increased Cornell's product was associated with a 5.3-to 9.3-fold higher chance of having LVH. Hence, although in isolation, no QT interval parameter performs better for LVH detection than simpler Cornell's product, it provides additive information and can be used in combination with voltage criteria to refine LVH risk stratification in resistant hypertension. Key Words: echocardiography Ⅲ electrocardiography Ⅲ hypertension, arterial Ⅲ hypertrophy R esistant hypertension (RH) is defined as uncontrolled office blood pressure (BP) in spite of an optimal regimen with Ն3 antihypertensive drugs at full dosages, always including a diuretic. 1 It is a clinical condition in which the persistently elevated BP levels frequently lead to the development of target-organ damage and to high cardiovascular morbidity and mortality. 2 Left ventricular hypertrophy (LVH) is strongly associated with cardiovascular mortality. 3 Subjects with LVH have an especially high risk of sudden cardiac death, up to several times that of those without LVH. 4 Prolonged QT interval duration or dispersion are associated with the occurrence of life-threatening ventricular arrhythmias and thus are presumed to represent potential predictors of increased cardiovascular risk. 5 In patients with hypertension, QT interval parameters have mainly been associated with left ventricular mass, 6,7 although 2 studies 8,9 suggested that they are no better than simple electrocardiographic voltage criteria for LVH detection. Moreover, it has been reported rec...

Relation of Left Ventricular Hypertrophy With Systemic Inflammation and Endothelial Damage in Resistant Hypertension

“…The characteristics of this cohort, as well as its enrollment criteria, baseline protocol, and diagnostic definitions, have been detailed previously. [13][14][15] In brief, all of the referred subjects with resistant hypertension (defined by office blood pressure [BP] Ն140/90 mm Hg using Ն3 antihypertensive drugs in full dosages always including a diuretic) were submitted to a standard protocol that included a complete clinical examination, laboratory evaluation, 24-hour ambulatory BP monitoring, and 2D echocardiography. UAER (measured by nephelometry; lower detection limit: 0.2 mg/dL; intra-assay and interassay variation coefficients: 4.3% and 4.4%, respectively) and proteinuria were evaluated in a sterile 24-hour urine collection.…”

Influence of Patern and Degree of Left Ventricular Hypertrophy on Cardiac Arrhythmias

“…In the LIFE study both concentric and eccentric LVH were associated with prolonged QTi and increased QTd [15]. In another study [46] QTd >60 ms and QTi >440 ms were associated with greater probability of LVH. In our patients, the QTi length correlates with the VA incidence.…”

The Prognostic Role of ECG in Arterial Hypertension

“…QT interval prolongation has been implicated in the origin of ventricular arrhythmias, possibly because of less uniform recovery of ventricular excitability in the setting of regional differences in cardiac sympathetic nervous system activity. In addition, the increased inhomogeneity of ventricular repolarization, induced by LVH, can be indirectly detected by QT dispersion, a relatively simple measurement of 12-lead electrocardiogram (ECG) variability, and this index has been recently shown to be related to poor prognosis in large population studies (Okin 2000, Salles 2005, Elming 1998, Bruyne 1998, Sheehana 2004. Interestingly, heterogeneous ventricular repolarization was initially recognized in standard ECGs as early as 1934; however only recently QTc interval dispersion was identified as a marker of arrhythmia risk and sudden cardiac death in patients after myocardial infarction or with heart failure (Barr 1994, Glancy 1995, Anastasiou-Nana 2000.…”