RESUMEN
OBJECTIVE: The aim of this cross-sectional study was to evaluate microvolt T-wave alternans (MTWA) as a marker of myocardial electrical instability in normotensive and hypertensive individuals with either nondipper or dipper-type circadian rhythm of blood pressure. MATERIALS AND METHODS: The study group included a total of 181 patients: 118 hypertensive patients and 63 normotensive healthy volunteers [mean age 46 ± 8; 34 men (54%)]. The patients with hypertension were divided into two groups on the basis of their results of 24-h ambulatory blood pressure monitoring: 61 patients with dipper hypertension [mean age 46 ± 6; 32 men (52.5%)] and 57 patients with nondipper hypertension [mean age 48 ± 10; 36 men (63.2%)]. The MTWAs of all patients were analyzed using the time-domain modified moving average method by means of a treadmill exercise stress test. RESULTS: MTWA positivity was statistically significantly different between all groups. Left ventricular mass index, E/E', interventricular septum, posterior wall, 24-h systolic blood pressure and diastolic blood pressure, and night-time systolic blood pressure and diastolic blood pressure were correlated positively with MTWA. Left ventricular mass index and the presence of nondipper hypertension were determined to be independent predictors of MTWA positivity. CONCLUSION: The blunting of the nocturnal decrease in blood pressure was associated with MTWA positivity in hypertensive patients.
