Alpha- and beta-adrenergic receptor polymorphisms in hypertensive and normotensive offspring.

BACKGROUND: The offspring of hypertensive families are characterized by higher arterial blood pressure values and a depressed autonomic control of heart rate. The present study aimed to verify whether these differences are associated with a different genotype distribution of functionally relevant polymorphisms of the alpha- and beta-adrenergic receptor (AR) genes. METHODS: We selected 109 age- and sex-matched young normotensive subjects with (FH+, n = 56) and without (FH-, n = 53) a family history of hypertension who underwent evaluation of arterial pressure; 24-h electrocardiogram monitoring to assess time-domain parameters of autonomic heart rate control [i.e. mean RR interval (NN), SD of RR intervals (SDNN) and mean square root of the differences of consecutive RR intervals (rMSSD)]; spectral baroreflex sensitivity measurement; and echo-Doppler to assess diastolic function and left ventricular mass. They were also characterized for the following polymorphisms by means of polymerase chain reaction-restriction fragment polymorphism analysis: Arg492Cys in the alpha1a-AR; Del301-303 in the alpha2b-AR; Ser49Gly and Arg389Gly in the beta1-AR; and the 5' leader cistron Arg19Cys, Arg16Gly and Gln27Glu in the beta2-AR. RESULTS: FH+ individuals showed a higher systolic pressure, a lower SDNN and a greater isovolumic relaxation time compared to normotensive offspring. No differences were found between the two groups when genotype distribution of the studied polymorphisms was considered. Subjects carrying alpha1a-AR Cys492 allelic variant showed lower values of NN, SDNN and rMSSD, independent of age, gender and body mass index. CONCLUSIONS: The functionally relevant polymorphisms of alpha2b-, beta1- and beta2-AR genes are not associated with a family history of essential hypertension. The Arg492Cys polymorphism of the alpha1a-AR gene, although not associated with a family history of hypertension, was strongly related to autonomic control of heart rate.

Prognostic value of brain natriuretic peptide in the management of patients receiving cardiac resynchronization therapy.

OBJECTIVE: To evaluate the role of brain natriuretic peptide (BNP) in predicting the progression of heart failure (HF) after cardiac resynchronization therapy (CRT). BACKGROUND: It has been shown that BNP predicts the prognosis and can guide the treatment of HF. METHODS: We studied 50 consecutive patients (61+/-10 years, 23 male) with HF (8 with ischaemic cardiomyopathy), NYHA class III, left bundle branch block, left ventricular ejection fraction (LVEF) 91.5 pg/ml had 89% sensitivity, 59% specificity, and negative and positive predictive values of 96% and 33%, respectively, for HF progression after 12 months. CONCLUSIONS: HF patients with high BNP values after 1 month of CRT have worse prognosis during follow-up. Therefore, in these patients other therapeutic options should be considered.

Independent and incremental prognostic value of endogenous ouabain in idiopathic dilated cardiomyopathy.

Increased circulating levels of endogenous ouabain (EO) have been observed in some heart failure patients, but their long term clinical significance is unknown. This study investigated the prognostic value of EO for worsening heart failure among 140 optimally treated patients (age 50+/-14 years; 104 male; NYHA class 1.9+/-0.7) with idiopathic dilated cardiomyopathy. Plasma EO was determined by RIA and by liquid chromatography mass spectrometry, values were linearly correlated (r = 0.89) in regression analysis. During follow-up (13+/-5 months), heart failure progression was defined as worsening clinical condition leading to one or more of the following: sustained increase in conventional therapies, hospitalization, cardiac transplant, or death. NYHA functional class, age, LVEF, peak VO2 and plasma levels of EO were predictive for heart failure progression. Heart failure worsened 1.5 fold (HR: 1.005; 95% CI: 1.001-1.007; p<0.01) for each 100 pmol/L increase in plasma EO. Moreover, those patients with higher plasma EO values had an odds ratio of 5.417 (95% CI: 2.044-14.355; p<0.001) for heart failure progression. Following multivariate analysis, LVEF, NYHA class and plasma EO remained significantly linked with clinical events. This study provides the first evidence that circulating EO is a novel, independent and incremental marker that predicts the progression of heart failure.

High circulating levels of endogenous ouabain in the offspring of hypertensive and normotensive individuals.

OBJECTIVE: Impaired diastolic function and left ventricular hypertrophy can occur early in the natural history of essential hypertension. High circulating levels of endogenous ouabain (EO) have been described in essential hypertension and have also been associated with left ventricular hypertrophy. The aim of this study was to investigate whether these cardiac modifications are related to plasma EO levels in the offspring of hypertensive families. METHODS: The study involved 41 subjects with (FAM+) and 45 subjects without (FAM-) a family history of hypertension. Arterial blood pressure, left ventricular geometry and function, and plasma EO levels were measured in each subject. RESULTS: Plasma EO levels were higher in the FAM+ subjects (221.5 +/- 10.95 versus 179.6 +/- 9.58 pmol/l, P = 0.004), and directly correlated with both systolic (r = 0.417, P < 0.0001) and diastolic blood pressure (r = 0.333, P = 0.002). Plasma EO was inversely related to an index of cardiac diastolic function determined as the ratio between the early and late peak flow velocity (r = -0.286, P = 0.012) and isovolumetric relaxation time (IVRT) (r = 0.32, P = 0.003). The IVRT was also significantly higher in FAM+, correlated with the IVRT (r = 0.32, P = 0.003). The IVRT was also significantly higher in FAM+, whereas the other echocardiographic parameters were similar to FAM-. CONCLUSIONS: Among the offspring of families with a positive history of hypertension, circulating EO levels and blood pressure are increased. Plasma EO levels are related to alterations of some indexes of diastolic heart function in these individuals.

Dynamics of ventricular repolarization in patients with dilated cardiomyopathy versus healthy subjects.

BACKGROUND: Patients with impaired left ventricular function have a high risk of developing ventricular arrhythmias and sudden death. Among different markers of risk, the prolongation and regional heterogeneity of repolarization are of increasing interest. However, there are limited data regarding feasibility of analyzing repolarization parameters and their dynamics in 24-hour Holter ECG recordings. METHODS: Dynamic behavior of repolarization parameters was studied with a new automatic algorithm in digital 24-hour Holter recordings of 60 healthy subjects and 55 patients with idiopathic dilated cardiomyopathy (IDC). Repolarization parameters included the mean value of QT and QTc durations, QT dispersion, and peaks of QT duration and QT dispersion above prespecified thresholds. RESULTS: In comparison to healthy subjects, patients with IDC had lower heart rate variability, longer mean QT and QTc durations, higher content of QTc peaks >500 ms, longer QT dispersion and its standard deviation, and a higher content of peaks >100 ms of QT dispersion (P < 0.01 for all comparisons). These repolarization parameters were significantly higher in IDC patients after adjustment for age, sex, and heart rate variability. The parameters of repolarization dynamics correlated with SDNN in healthy subjects but not in dilated cardiomyopathy patients. CONCLUSIONS: The automatic assessment of repolarization parameters in 24-hour digital ECG recordings is feasible and differentiates dilated cardiomyopathy patients from healthy subjects. Patients with dilated cardiomyopathy have increased QT duration, QT dispersion, and increased variability of QT dispersion reflecting variations in T-wave morphology, the factors which might predispose them to the development of arrhythmic events.

Ventricular asynchrony predicts a better outcome in patients with chronic heart failure receiving cardiac resynchronization therapy.

OBJECTIVES: The aim of this study was to evaluate whether the clinical benefit of cardiac resynchronization therapy (CRT) can be prospectively predicted by means of the baseline evaluation of left ventricular asynchrony. BACKGROUND: The reverse remodeling associated with CRT is more evident in patients with severe heart failure (HF) and left bundle branch block (LBBB) who have left ventricular asynchrony. METHODS: Baseline left ventricular asynchrony was assessed in 60 patients with severe HF and LBBB by calculating the electrocardiographic duration of QRS and the echocardiographic septal-to-posterior wall motion delay (SPWMD). Left ventricular size and left ventricular ejection fraction (LVEF), mitral valve regurgitation, and functional capacity were also evaluated. The progression toward HF (defined as a worsening clinical condition leading to a sustained increase in conventional therapies, hospitalization, cardiac transplantation, and death) was assessed during follow-up, as were the changes in LVEF after six months. RESULTS: During the median follow-up of 14 months, 16 patients experienced HF progression. Univariate analysis showed that ischemic cardiomyopathy, changes in the QRS duration after implantation, and SPWMD significantly correlated with events. At multivariate analysis, a long SPWMD remained significantly associated with a reduced risk of HF progression (hazard ratio: 0.91; 95% confidence interval: 0.83 to 0.99; p <0.05). An improvement in LVEF was observed in 79% of the patients with a baseline SPWMD of > or =130 ms and in 9% of those with an SPWMD of <130 ms (p <0.0001). CONCLUSIONS: Baseline SPWMD is a strong predictor of long-term clinical improvement after CRT in patients with severe HF and LBBB.

Association of beta-adrenergic receptor polymorphisms and progression to heart failure in patients with idiopathic dilated cardiomyopathy.

PURPOSE: Increased sympathetic nervous system activation via the beta-adrenergic pathway influences the evolution of idiopathic dilated cardiomyopathy. We assessed the effects of beta-adrenergic receptor variants on heart failure in idiopathic dilated cardiomyopathy. METHODS: We prospectively analyzed 171 consecutive patients (mean [+/- SD] age, 49 +/- 14 years; 129 men) with idiopathic dilated cardiomyopathy who were receiving conventional treatment. All were characterized by polymerase chain reaction-restriction fragment length polymorphism analysis for Ser49Gly and Arg389Gly in the beta1-adrenergic receptor; the 5' leader cistron (LC) Arg19Cys, Arg16Gly, Gln27Glu, and Thr164Ile in the beta2-adrenergic receptor; and Arg64Trp in the beta3-adrenergic receptor. The endpoint was heart failure, defined as a worsening of clinical condition leading to hospitalization for heart failure, cardiac transplantation, or death from heart failure. RESULTS: During a median follow-up of 33 months, 24 patients had heart failure. In a Cox univariate analysis, the beta1Gly49 and beta2 5'LC-Cys19, Arg16, and Gln27 alleles were associated with a lower risk of heart failure. In a multivariate analysis that considered age, functional class, left ventricular ejection fraction, and beta-blocker use, three beta2-adrenergic receptor alleles were associated with lower risk: 5'LC-Cys19 (hazard ratio [HR]: 0.15; 95% confidence interval [CI]: 0.05 to 0.42), Arg16 (HR: 0.12; 95% CI: 0.04 to 0.35), and Gln27 (HR: 0.15; 95% CI: 0.05 to 0.42). CONCLUSION: The Gly49 allele in the beta1-adrenergic receptor and the 5' LC-Cys19, Arg16, and Gln27 alleles in the beta2-adrenergic receptor were associated with a lower risk of heart failure in idiopathic dilated cardiomyopathy, suggesting that the beta1- and beta2-adrenergic receptor genes are modifier genes.

Comparison of the effect of valsartan and lisinopril on autonomic nervous system activity in chronic heart failure.

BACKGROUND: In chronic heart failure (CHF), the derangement of autonomic nervous system activity has a deep impact on the progression of the disease. It has been demonstrated that modulation of the renin-angiotensin aldosterone system (RAAS) increases autonomic control of heart rate and reduces adrenergic activity. We sought to evaluate, in CHF, the different effects of an ACE inhibitor (lisinopril) and of an AT1 receptor antagonist (valsartan) on heart rate variability, baroreflex sensitivity and norepinephrine plasma levels. METHODS: Ninety patients (61 +/- 10 years, 2.3 +/- 0.5, New York Heart Association class) with CHF and left ventricular ejection fraction <40% were randomly assigned in a double-blind fashion to receive lisinopril (uptitrated to 20 mg/d) or valsartan (uptitrated to 160 mg/d) therapy for 16 weeks. Heart rate variability (evaluated by measuring standard deviation of normal R-R intervals on 24-hour ECG recordings), spontaneous baroreflex sensitivity and aldosterone and norepinephrine plasma levels were assessed before and after drug therapy. RESULTS: There were no significant differences between valsartan and lisinopril in their effects on left ventricular function, arterial pressure, aldosterone plasma levels and autonomic control of heart rate. Both lisinopril and valsartan significantly reduced plasma norepinephrine levels, but the reduction induced by valsartan was significantly greater than that observed for lisinopril (27% vs 6%, P <.05). CONCLUSIONS: This study shows a comparable effect of ACE inhibition (lisinopril) and of AT1 receptor antagonism (valsartan) on cardiac vagal control of heart rate, whereas valsartan has shown a more effective modulation of sympathetic activity measured by plasma norepinephrine levels.

QT-interval prolongation in right precordial leads: an additional electrocardiographic hallmark of Brugada syndrome.

OBJECTIVES: The aim of this study was to evaluate whether the occurrence of the Brugada Syndrome typical electrocardiogram (ECG) pattern (i.e., right bundle branch block, coved-type ST-segment elevation, and T-wave inversion in the right precordial leads) is characterized by a concomitant lengthening of QT intervals in the right precordial leads. BACKGROUND: It has been suggested that the typical ECG pattern of Brugada syndrome is due to a decreased net inward current during phase 1 of the action potential, which also leads to its prolongation in the right epicardium. METHODS: Thirty-two subjects (19 males) age 37 +/- 15 years with a suspicious baseline ECG, or who were relatives of Brugada syndrome patients, underwent 12-lead ECG before and after the administration of flecainide. RESULTS: The flecainide test was negative in 14 and positive in 18 subjects. After flecainide administration, the positive ECGs were characterized by a greater QT interval corrected for heart rate (QTc) prolongation in the right precordial leads than that in the negative ECGs (78.2 +/- 35.5 ms vs. 22.0 +/- 28.4 ms in V(1) and 107.1 +/- 43.8 ms vs. 26.7 +/- 30.1 ms in V(2); p < 0.01), whereas there was no difference in the QTc prolongation in the left precordial leads (55.2 +/- 25.3 ms vs. 35.1 +/- 28.1 ms in V(5) and 53.1 +/- 32.8 ms vs. 27.3 +/- 22.4 ms in V(6); p = NS). CONCLUSIONS: In accordance with the electrophysiological background, the typical ECG pattern of Brugada syndrome is also characterized by a considerable prolongation of the QT interval in right precordial leads.

Allelic variants of natriuretic peptide receptor genes are associated with family history of hypertension and cardiovascular phenotype.

OBJECTIVE: Abnormalities in the natriuretic peptide system could play a key role in the genesis of hypertension. We evaluated the associations between a family history of hypertension, cardiovascular phenotype and allelic variants of Npr1 and Npr3, two candidate genes that codify for natriuretic peptide receptors. METHODS: We genotyped 45 young normotensive subjects (19 males, 26.8 +/- 3.7 years) with accurately assessed family history of hypertension (FH+) and 52 (26 males, 26.1 +/- 3.1 years) without (FH-) for the known variants of Npr1 and Npr3 genes, and for a novel length difference (3C/4C) polymorphism at position 15129 in the 3'-untranslated region of the Npr1 gene. Blood pressure, echocardiography and plasma brain natriuretic peptide were assessed. RESULTS: Both the novel Npr1 3C allele (59 versus 33%, P < 0.001) and the 3C/3C genotype (31 versus 8%; P < 0.001) were significantly more frequent in FH+ than in FH-. The inverse distribution of the 4C/4C genotype suggested that a casual association was very unlikely. Moreover, the 3C/3C homozygous had significantly higher systolic blood pressure (121.1 +/- 6.3 versus 115.6 +/- 7.8 mmHg in 4C/4C; P < 0.05) and a longer left ventricular isovolumic relaxation time (67 +/- 10 versus 61 +/- 9 ms; P < 0.05). The Npr3 C(-55) allele variant was also more frequent in FH+ (88 versus 76%, P < 0.05), but was not associated with the cardiovascular phenotype. CONCLUSIONS: The novel Npr1 gene 3C variant and the Npr3 gene C(-55) allele are associated with hypertensive family history. Moreover, the functional Npr1 3C variant, when homozygous, is also associated with higher systolic blood pressure and prolonged ventricular relaxation.

Cardiac resynchronization therapy tailored by echocardiographic evaluation of ventricular asynchrony.

OBJECTIVES: The value of interventricular and intraventricular echocardiographic asynchrony parameters in predicting reverse remodeling after cardiac resynchronization therapy (CRT) was investigated. BACKGROUND: Cardiac resynchronization therapy has been suggested as a promising strategy in patients with severe heart failure and left bundle branch block (LBBB), but the entity of benefit is variable and no criteria are yet available to predict which patients will gain. METHODS: Interventricular and intraventricular mechanical asynchrony was evaluated in 20 patients (8 men and 12 women, 63 +/- 10 years) with advanced heart failure caused by ischemic (n = 4) or nonischemic dilated cardiomyopathy (n = 16) and LBBB (QRS duration of at least 140 ms) using echocardiographic Doppler measurements. Left ventricular end-diastolic volume index (LVEDVI) and left ventricular end-systolic volume index (LVESVI) were calculated before and one month after CRT. Patients with a LVESVI reduction of at least 15% were considered as responders. RESULTS: Cardiac resynchronization therapy significantly improved ventricular volumes (LVEDVI from 150 +/- 53 ml/m(2) to 119 +/- 37 ml/m(2), p < 0.001; LVESVI from 116 +/- 43 ml/m(2) to 85 +/- 29 ml/m(2), p < 0.0001). At baseline, the responders had a significantly longer septal-to-posterior wall motion delay (SPWMD), a left intraventricular asynchrony parameter; only QRS duration and SPWMD significantly correlated with a reduction in LVESVI (r = -0.54, p < 0.05 and r = -0.70, p < 0.001, respectively), but the accuracy of SPWMD in predicting reverse remodeling was greater than that of the QRS duration (85% vs. 65%). CONCLUSIONS: In patients with advanced heart failure and LBBB, baseline SPWMD is a strong predictor of the occurrence of reverse remodeling after CRT, thus suggesting its usefulness in identifying patients likely to benefit from biventricular pacing.

[Natriuretic peptides and essential arterial hypertension]. / Peptidi natriuretici e ipertensione arteriosa essenziale.

Natriuretic peptide system plays a well-defined role in the regulation of blood pressure and fluid volume. Although the effects of natriuretic peptides (atrial natriuretic peptide, brain natriuretic peptide and C-type natriuretic peptide) are mediated by specific biologic receptors, their plasma level is influenced by clearance receptors. It has been demonstrated that in hypertensive subjects plasma levels of natriuretic peptides are impaired; furthermore peptide receptor polymorphisms have been shown to be significantly associated with hypertension and cardiac hypertrophy. Studying normotensive subjects at high genetic risk of developing hypertension on the basis of family history makes it possible to investigate the role of natriuretic peptide system in the genesis of hypertension. It has been shown that plasma atrial and ventricular natriuretic peptide levels are significantly reduced in normotensive subjects with a family history of hypertension. Our study is the first one showing association among positive family history of essential hypertension and natriuretic peptide receptor polymorphisms. We identified a novel insertion/deletion polymorphism at position 15,129 in the 3'-untranslated region (3'-UTR) of NPRA receptor mRNA. The NPRA gene deletion variant is associated with hypertensive family history and higher systolic blood pressure. The "deletion 15129" variant might participate in the functional impairment of natriuretic peptide system defining an increased genetic susceptibility to hypertension.