Prognostic impact of prolonged ventricular repolarization in hypertension.
BACKGROUND
QT interval prolongation on the surface electrocardiogram (ECG) predicts cardiovascular complications in high-risk subjects, but its prognostic role in uncomplicated hypertension has been understudied.


METHODS
For up to 13 years (average, 5.3 years), we followed up 2110 white patients with initially untreated essential hypertension (mean +/- SD age, 49 +/- 12 years; 55% men) without prevalent cardiovascular or renal disease who underwent 12-lead ECG before therapy. We excluded patients with ECG abnormalities including ischemia, necrosis, complete bundle branch block, atrial fibrillation, arrhythmias, and ventricular preexcitation.


RESULTS
Heart rate-corrected QT interval (QTc) showed a weak but significant direct association with systolic blood pressure (r = 0.07; P<.001), diastolic blood pressure (r = 0.11; P<.001), and Cornell voltage (r = 0.06; P = .006). During follow-up, 84 patients developed new-onset ischemic heart disease (0.75 event per 100 patient-years). After adjustment (Cox model) for the effects of age, sex, diabetes mellitus, serum cholesterol level, serum creatinine level, smoking, left ventricular hypertrophy, and 24-hour systolic blood pressure, patients with a prolonged QTc (>or=450 milliseconds in women and >or=440 milliseconds in men) had a nearly 2-fold increase in risks of coronary events (hazard ratio, 1.95; 95% confidence interval, 1.12-3.42; P = .02) and cardiovascular death (hazard ratio, 2.05; 95% confidence interval, 1.03-4.37; P = .04). Coronary heart disease risk was independently higher by 33% (95% confidence interval, +7% to +66%; P = .01) for each 32-millisecond increase in QTc.


CONCLUSIONS
Prolonged ventricular repolarization is a risk factor for ischemic heart disease and cardiovascular mortality in subjects with uncomplicated hypertension. Its prognostic significance adds to that of several traditional cardiovascular risk factors, including left ventricular hypertrophy.
Schillaci
Giuseppe
G
Unit of Internal Medicine, Angiology and Arteriosclerosis, Department of Clinical and Experimental Medicine, University of Perugia Medical School, Hospital Santa Maria della Misericordia, Piazzale Menghini, 1, 06132 Perugia, Italy. skill@unipg.it
Pirro
Matteo
M
Ronti
Tiziana
T
Gemelli
Fabio
F
Pucci
Giacomo
G
Innocente
Salvatore
S
Porcellati
Carlo
C
Mannarino
Elmo
E
D003327:Coronary Disease / Q000209:etiology* / Q000401:mortality / Q000503:physiopathology; D018450:Disease Progression; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006329:Heart Conduction System / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology*; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D012307:Risk Factors; D015996:Survival Rate / Q000639:trends; D013997:Time Factors