Giannina Leotta

QT interval in patients with primary aldosteronism and low-renin essential hypertension.

Introduction QT interval prolongation increases the risk of sudden death in several medical conditions. Patients with primary aldosteronism and salt-sensitive hypertension experience more cardiovascular events than those with normal-renin essential hypertension. QT interval prolongation might represent one of the risk factors for cardiovascular events in these patients. The aim of the present study was to evaluate the QT interval in patients with primary aldosteronism and low-renin essential hypertension (LREH). Methods Twenty-seven patients with primary aldosteronism, 17 patients with LREH, 117 patients with essential hypertension and 25 healthy individuals were studied. Plasma aldosterone, plasma renin activity, and aldosterone to plasma renin activity ratio (ARR) were determined. Corrected QT intervals (QTcs) were measured from a 12-lead electrocardiogram. Results The QTc was longer in primary aldosteronism (434 ± 23 ms) and LREH (430 ± 18 ms) compared with essential hypertension (419 ± 22 ms) and healthy controls (412 ± 19 ms) (P = 0.0004). The prevalence of QTc longer than 440 ms was higher in primary aldosteronism (48%) and LREH (23%) compared with essential hypertension (11%) and healthy controls (4%) (P < 0.0001). QTc correlated with plasma aldosterone (P = 0.01), ARR (P = 0.02), and diastolic blood pressure (P = 0.01). ARR (P = 0.01) and systolic blood pressure (P = 0.01) were identified as independent predictors of QTc. Conclusions We postulate that the elevated aldosterone secretion contributes to the prolongation of the QT interval in patients with primary aldosteronism and LREH through both a depletion of intracellular potassium concentration and higher blood pressure values. QTc measurement might represent one simple, non-invasive and reproducible index to characterize the cardiovascular risk in patients with primary aldosteronism and LREH.

Relationship between QT interval and cardiovascular risk factors in healthy young subjects

A prolongation of QT interval increases the risk for coronary heart disease, ventricular arrhythmias, and sudden death in diabetic patients, after myocardial infarction, and in the elderly. An association between QT prolongation and cardiovascular risk factors has been demonstrated in middle-aged and elderly subjects. Aims of this study were to evaluate the prevalence of a prolonged corrected QT interval (QTc) in a healthy young population (n=170, age 22–25 years, 84 males) and to investigate the association of QTc and QT dispersion (QTd) with cardiovascular risk factors (body mass index, blood pressure, fasting blood glucose and cholesterol, smoking habits, and hypertensive familiarity). A prolonged QTc was observed in 10% of female and 5% of male subjects; in multiple regression analysis, QTc showed a significant positive relationship with blood glucose in females (P=0.04) and systolic blood pressure in male subjects (P=0.03), while QTd was not significantly related with any of the factors. In conclusion, the association between QTc length, glucose levels, and blood pressure is present also in young healthy subjects. QT measurement may represent a useful marker in the screening of young subjects for cardiovascular prevention.

Characteristics of the patients referred to a Hypertension Unit between 1989 and 2003

The level of blood pressure, the type of antihypertensive treatment and the prevalence of resistant hypertension at the first examination were evaluated in 6254 patients referred to a hospital Hypertension Unit from 1989 to 2003. From 1989-1993 to 1999-2003, we observed a reduced prevalence of grade 2 and grade 3 hypertension, and an increase in the prevalence of grade 1 hypertension, the proportion of treated subjects, the average number of antihypertensive drugs per patient and the prevalence of resistant hypertension.

Efficacy of antihypertensive treatment based on plasma renin activity: An open label observational study

Abstract Background. We investigated the extent of blood pressure (BP) reduction and control (<140/90 mmHg) in patients treated with appropriate or inappropriate drugs according to their plasma renin activity (PRA) level (natriuretic drugs and renin–angiotensin system blockers for low-renin and high-renin hypertension, respectively). Patients and methods. One hundred and seventy Caucasian untreated hypertensive patients (61 females), aged 18–70 years, participated to the study. Patients with secondary hypertension, diabetes or established cardiovascular or renal disease were excluded. The physician prescribed an antihypertensive monotherapy chosen among all drug classes, unaware of patients PRA levels. We compared effect of an inappropriate or appropriate drug, evaluating BP values after a month of treatment. Results. Rate of BP control was not significantly higher in patients treated with an appropriate drug than the others (38% vs 29%, p=0.24). However, in a regression analysis, final diastolic BP (DBP) was lower in subjects treated with an appropriate drug (β=−2.84, p=0.03). Conclusions. The present study does not clearly support the use of PRA in a general population of hypertensive patients to optimize BP control. However, the greater efficacy of a drug appropriate to PRA in reducing DBP may be clinically helpful in young hypertensive patients. Future studies are warranted to evaluate if PRA determination enhances the therapeutic success in patients with predominantly high values of DBP.

Pulse rate in childhood: reference limits

BACKGROUND AND AIM Systematic quantitative resting pulse rate measurements may represent an additional parameter for the study of cardiovascular risk factors in youth as well as in adulthood. The aim of this study was to evaluate resting pulse rate and its distribution curve in order to define reference limits in a sample of adolescents from Turin, Italy. METHODS AND RESULTS The study population consisted of 2230 children aged 12-18 years, who were randomly enrolled from Turin Junior High Schools. All of the participants underwent pulse rate, blood pressure and height measurements. The 5th and 95th percentiles of the pulse rate in boys and girls are reported by age and height. The pulse rate was higher in the girls, but progressively decreased with age and somatic growth in both genders. CONCLUSIONS The present study provides reference blood pressure values by age, gender and height in a sample of male and female adolescents.

Effects of Antihypertensive Drugs on the Renin-Angiotensin System in Essential Hypertension

A standardized approach to antihypertensive pharmacological therapy taking into account the pathophysiological mechanism of hypertension is not yet available. Laragh and colleagues have proposed a model based on the concept that the two final determinants of blood pressure are the volume status and the renin-angiotensin-aldosterone system. This model allows patients to be divided into two categories based on plasma renin activity (<0.65 or >0.65 ng/mL) and with a different primary target for a specific therapy. In Laragh’s opinion, all antihypertensive drugs could be divided into two groups according to their mechanism of action: drugs that block the activity of the renin-angiotensin system (R drugs, such as β-adrenoceptor antagonists [β-blockers], ACE inhibitors, angiotensin II type 1 receptor antagonists [angiotensin receptor blockers] and centrally acting antihypertensive drugs) or drugs that increase renal sodium excretion (V drugs, such as diuretics, α-adrenoceptor antagonists [α-blockers] or calcium channel blockers). This article reviews the mechanisms underlying this antihypertensive drug classification.

Drug effects on aldosterone/plasma renin activity ratio in primary aldosteronism

Abstract—Primary aldosteronism is a specifically treatable and potentially curable form of secondary hypertension. The aldosterone/plasma renin activity ratio (ARR) is routinely used as a screening test. Antihypertensive therapy can interfere with the interpretation of this parameter, but a correct washout period can be potentially harmful. We have investigated the effects of therapy with atenolol, amlodipine, doxazosin, fosinopril, and irbesartan on the ARR in a group of 230 patients with suspected primary aldosteronism. The percent change from control of ARR in patients taking amlodipine was −17%±32; atenolol, 62%±82; doxazosin, −5%±26; fosinopril, −30%±24; and irbesartan, −43%±27. The ARR change induced by atenolol was significantly higher compared with that induced by all other drugs (P <0.0001), and the ARR change induced by irbesartan was significantly lower than that induced by doxazosin (P <0.0001). One of 55 patients from the group taking amlodipine (1.8%) and 4/17 of the patients taking irbesartan (23.5%) gave a false-negative ARR (<50). None of the patients of the groups taking fosinopril, doxazosin, and atenolol displayed a false-negative ARR. Doxazosin and fosinopril can be used in hypertensive patients who need to undergo aldosterone and PRA measurement for the diagnosis of primary aldosteronism; amlodipine gave a very small percentage of false-negative diagnoses. &bgr;-Blockers also do not interfere with the diagnosis of primary aldosteronism, but they can be responsible for an increased rate of false-positive ARRs. The high rate of false-negative diagnoses in patients undergoing irbesartan treatment requires confirmation in a higher number of patients.