Pietro Guida

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.

SCN5A Polymorphism Restores Trafficking of a Brugada Syndrome Mutation on a Separate Gene

Background— Brugada syndrome is associated with a high risk of sudden cardiac death and is caused by mutations in the cardiac voltage-gated sodium channel gene. Previously, the R282H-SCN5A mutation in the sodium channel gene was identified in patients with Brugada syndrome. In a family carrying the R282H-SCN5A mutation, an asymptomatic individual had a common H558R-SCN5A polymorphism and the mutation on separate chromosomes. Therefore, we hypothesized that the polymorphism could rescue the mutation. Methods and Results— In heterologous cells, expression of the mutation alone did not produce sodium current. However, coexpressing the mutation with the polymorphism produced significantly greater current than coexpressing the mutant with the wild-type gene, demonstrating that the polymorphism rescues the mutation. Using immunocytochemistry, we demonstrated that the R282H-SCN5A construct can traffic to the cell membrane only in the presence of the H558R-SCN5A polymorphism. Using fluorescence resonance energy transfer and protein fragments centered on H558R-SCN5A, we demonstrated that cardiac sodium channels preferentially interact when the polymorphism is expressed on one protein but not the other. Conclusions— This study suggests a mechanism whereby the Brugada syndrome has incomplete penetrance. More importantly, this study suggests that genetic polymorphisms may be a potential target for future therapies aimed at rescuing specific dysfunctional protein channels.

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.

Prognostic role of sub-clinical hypothyroidism in chronic heart failure outpatients

BACKGROUND It has been suggested that low thyroid hormones levels may be associated with increased mortality in patients with cardiovascular disease. AIM To evaluate the prognostic role of thyroid function deficiency in patients with chronic heart failure (CHF). METHODS We evaluated 338 consecutive outpatients with stable CHF receiving conventional therapy, all of whom underwent a physical examination, electrocardiography and echocardiography. Blood samples were drawn to assess renal function, and Na+, hemoglobin, NT-proBNPs, fT3, fT4 and TSH levels. Patients with hyperthyroidism were excluded. RESULTS During the follow-up (15+/-8 months), heart failure progression was observed in 79 patients (including 18 who died of heart failure after hospitalisation and six who underwent transplantation). Univariate regression analysis showed that TSH (p<0.0001), fT3 (p<0.0001), fT4 (p=0.016) and fT3/fT4 (p<0.0001) were associated with heart failure progression but multivariate analysis showed that only TSH considered as a continuous variable (p = 0.001) as well as subclinical hypothyroidism (TSH > 5.5 mUI/l; p=0.014) remained significantly associated with the events. CONCLUSIONS In CHF patients TSH levels even slightly above normal range are independently associated with a greater likelihood of heart failure progression. This supports the need for prospective studies aimed at clarifying the most appropriate therapeutic approach to sub-clinical hypothyroidism in such patients.

Serum Uric Acid and Risk of CKD in Type 2 Diabetes

BACKGROUND AND OBJECTIVE Serum uric acid may predict the onset and progression of kidney disease, but it is unclear whether uric acid is an independent risk factor for diabetic nephropathy. Our aim was to study the relationship between uric acid levels and the development of CKD components in patients with type 2 diabetes. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Longitudinal study of a cohort of patients with type 2 diabetes from the database of the Italian Association of Clinical Diabetologists network. From a total of 62,830 patients attending the diabetes centers between January 1, 2004, and June 30, 2008, we considered those with baseline eGFR values ≥60 ml/min per 1.73 m2 and normal albumin excretion (n=20,142). Urinary albumin excretion, GFR, and serum uric acid were available in 13,964 patients. We assessed the association of serum uric acid quintiles with onset of CKD components by multinomial logistic regression model adjusting for potential confounders. We calculated the relative risk ratios (RRRs) for eGFR <60 ml/min per 1.73 m2, albuminuria, and their combination at 4 years. RESULTS At 4-year follow-up, 1109 (7.9%) patients developed GFR <60 ml/min per 1.73 m2 with normoalbuminuria, 1968 (14.1%) had albuminuria with eGFR ≥60 ml/min per 1.73 m2, and 286 (2.0%) had albuminuria with eGFR <60 ml/min per 1.73 m2. The incidence of eGFR <60 ml/min per 1.73 m2 increased in parallel with uric acid quintiles: Compared with the lowest quintile, RRRs were 1.46 (95% confidence interval [CI], 1.14 to 1.88; P=0.003), 1.44 (95% CI, 1.11 to 1.87; P=0.006), 1.95 (95% CI, 1.48 to 2.58; P<0.001), and 2.61 (95% CI, 1.98 to 3.42; P<0.001) for second, third, fourth, and fifth quintiles, respectively. Serum uric acid was significantly associated with albuminuria only in presence of eGFR <60 ml/min per 1.73 m2. CONCLUSIONS Mild hyperuricemia is strongly associated with the risk of CKD in patients with type 2 diabetes.

Independent role of left ventricular global longitudinal strain in predicting prognosis of chronic heart failure patients.

To evaluate the independent prognostic role of two‐dimensional (2D) strain measures reflecting global longitudinal left ventricular (LV) systolic function in outpatients affected by chronic heart failure (CHF).

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.

Influence of gender and family history of hypertension on autonomic control of heart rate, diastolic function and brain natriuretic peptide

Objective To verify in a unitary view whether autonomic control of heart rate and cardiac structure and function are modified early in offspring of hypertensive families. Methods and results We selected 87 age- and sex-matched young normotensive subjects with (n = 45) and without (n = 42) a family history of hypertension who underwent evaluations of arterial pressure, time-domain parameters of autonomic heart rate control (24-h ECG monitoring), spectral baroreflex sensitivity, left ventricular geometry and function (echo-Doppler) and plasma brain natriuretic peptide levels (BNP). The group with a family history of hypertension significantly differed from their counterparts for systolic pressure (119 ± 11 versus 114 ± 9 mmHg, P< 0.05), heart rate (RR interval, 766 ± 64 versus 810 ± 93 ms, P< 0.05), heart rate variability [the standard deviation of normal RR intervals (SDNN), 147 ± 29 versus 171 ± 33 ms, P< 0.05], diastolic function (isovolumetric relaxation time, 65 ± 9 versus 60 ± 8 ms, P< 0.05) and BNP (23 ± 13 versus 37 ± 10 pg/ml, P< 0.05). Baroreflex sensitivity values did not differ between the two groups. When gender was considered, all the above-mentioned measures, as well as baroreflex sensitivity, were significantly different between males with and without a family history of hypertension but not between females, except for BNP, which was lower in males and females with a history of hypertension (males, 24 ± 11 versus 38 ± 8 pg/ml, P< 0.01; females 21 ± 14 versus 36 ± 13 pg/ml, P< 0.05). Conclusions Male, but not female, hypertensive offspring have modified diastolic function and autonomic control of heart rate; BNP is the only parameter able to characterize hypertensive offspring independently from the influence of gender. This provides the hypothesis that the impaired production of this hormone could play a primary role in the pre-hypertensive state.

Head-up tilt testing for diagnosing vasovagal syncope: a meta-analysis.

BACKGROUND A systematic evaluation focused on sensitivity and specificity of head-up tilt testing (HUT) for diagnosing vasovagal syncope has not been previously performed. We conducted a meta-analysis of studies comparing HUT outcome between patients with syncope of unknown origin and control subjects without previous syncope. METHODS We searched Pubmed and Embase databases for all English-only articles concerning case-control studies estimating the diagnostic yield of HUT, and selected 55 articles, published before March 2012, including 4361 patients and 1791 controls. The influence of age, test duration, tilt angle, and nitroglycerine or isoproterenol stimulation on tilt testing outcome was analyzed. RESULTS Head-up tilt testing demonstrated to have a good overall ability to discriminate between symptomatic patients and asymptomatic controls with an area under the summary receiver-operating characteristics curve of 0.84 and an adjusted diagnostic odds ratio of 12.15 (p<0.001). A significant inverse relationship between sensitivity and specificity of tilt testing for each study was observed (p<0.001). At multivariate analysis, advancing age and a 60° tilt angle showed a significant effect in reducing sensitivity and increasing specificity of the test. Nitroglycerine significantly raised tilt testing sensitivity by maintaining a similar specificity in comparison to isoproterenol. CONCLUSIONS The results from this meta-analysis show the high overall performance of HUT for diagnosing vasovagal syncope. Our findings provide useful information for evaluating clinical and instrumental parameters together with pharmacological stressors influencing HUT accuracy. This could allow the drawing of tilt testing protocols tailored on the diagnostic needs of each patient with unexplained syncope.

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

To evaluate the role of brain natriuretic peptide (BNP) in predicting the progression of heart failure (HF) after cardiac resynchronization therapy (CRT).