Long-term improvement of QT dispersion is unaffected by short-term changes in blood pressure during treatment of systemic hypertension with enalapril.
BACKGROUND
We report the reduction of QT and QTc dispersion in patients treated for 7 years with enalapril for systemic hypertension with left ventricular (LV) hypertrophy. We assess the correlation between QT dispersion and LV mass during this period and at the end of an 8-week period of suspension of enalapril treatment after 5 years.


METHODS
Twenty-four previously untreated patients with this condition took enalapril (20 mg twice daily) for 7 years, except during an 8-week period following 5-year follow-up. Cardiovascular parameters were determined by two-dimensional guided M-mode echocardiography, and QT interval was measured, in a pretreatment placebo phase, 8 weeks and 1, 3, 5, and 7 years after the start of the therapy, at the end of the 8-week suspension effected after 5 years, and 8 weeks after the end of the suspension.


RESULTS
Therapy rapidly reduced blood pressure (BP) from 156/105 mmHg to normal values: 134/84 mmHg after 8 weeks' treatment, 130-84 mmHg at 7-year follow-up (P < 0.001 with respect to the placebo phase). LV mass index decreased progressively until at 5-year follow-up the reduction had reached 39% (P < 0.001), after which neither LV mass nor any other structural parameter underwent any further significant change. During this time, QT dispersion (DeltaQT) and the dispersion of "corrected" QT (DeltaQTc) decreased significantly: DeltaQT (from 61 +/- 21 to 37 +/- 13 ms) and DeltaQTc (from 67 +/- 27 to 41 +/- 16 ms). After suspension of treatment for 8 weeks following 5-year follow-up, DeltaQT was 40 +/- 14 ms and DeltaQTc was 44 +/- 17 ms; there were no significant changes either in DeltaQT and DeltaQTc or LV hypertrophy although BP had returned to pretreatment values (BP: 150 +/- 16; 101 +/- 10 mmHg).


CONCLUSIONS
Long-term enalapril treatment of hypertensive patients with LV hypertrophy induces marked regression of LV mass and improvement of QT dispersion. These improvements occur on a longer timescale than improvement in BP, and are not affected by transient changes in BP values.
Seara
Francisco Javier García
FJ
Cardiology Department, Hospital Clínico Universitario de Santiago de Compostela, Spain. javierseara@mixmail.com
Juanatey
José Ramón González
JR
Sande
José Luis Martínez
JL
Veloso
Pedro Rigueiro
PR
Reino
Antonio Pose
AP
Román
Alfonso Varela
AV
Cerrato
José Cabezas
JC
Peña
Miguel Gil de la
MG
D000328:Adult; D000368:Aged; D000959:Antihypertensive Agents / Q000494:pharmacology* / Q000627:therapeutic use; D015897:Comorbidity; D004562:Electrocardiography; D004656:Enalapril / Q000494:pharmacology* / Q000627:therapeutic use; D005260:Female; D006329:Heart Conduction System / Q000187:drug effects* / Q000503:physiopathology*; D006801:Humans; D006973:Hypertension / Q000453:epidemiology; D017379:Hypertrophy, Left Ventricular / Q000453:epidemiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D013318:Stroke Volume / Q000187:drug effects; D016277:Ventricular Function, Left / Q000187:drug effects
D000959:Antihypertensive Agents; D004656:Enalapril