Impact of diastolic Doppler indices on exercise capacity in hypertensive patients with electrocardiographic left ventricular hypertrophy (a LIFE substudy)

Subclinical HMOD in Hypertension: Left Ventricular Diastolic Dysfunction

Arterial hypertension represents an important risk factor for the development of cardiac, vascular and renal events, predisposing to heart failure, acute coronary syndromes, peripheral artery disease, stroke, and chronic renal disease. Arterial hypertension leads to the development of subclinical hypertension mediated organ damage (HMOD) which has prognostic relevance and may influence the choice of treatment options. Alterations of cardiac structure and function represent the more widely assessed form of HMOD. This manuscript will focus on the diagnostic opportunities, prognostic significance and treatment of diastolic dysfunction alterations.

Delayed Myocardial Enhancement in Pediatric Hypertrophic Cardiomyopathy: Correlation with LV Function, Echocardiography, and Demographic Parameters

Our aim was (1) to detect the presence of fibrosis by Cardiac magnetic resonance imaging (CMR) in the pediatric age group. (2) Correlate CMR findings with demographic data, LV function, and other echocardiographic parameters. We studied 40 pediatric patients diagnosed as HCM by echocardiography. All patients were subjected to clinical examination (in which the NYHA classification was determined for each patient), echocardiography, and CMR. CMR was done on a 1.5T Philips Achieva scanner in SSFP with delayed myocardial enhancement (DE-MRI). All demographic and functional parameters as well as pressure gradient across left ventricular outflow tract (LVOT) were correlated with the percentage of myocardial enhancement. We studied 13 female and 27 male patients from 45 days up to 18 years. The mean percentage of DE-MRI was 9.7 ± 9%. We found significant correlation between the NYHA classification and the pressure gradient across the LVOT (P = < 0.001) as well as the percentage of DE-MRI (P = 0.004). The percentage of DE-MRI showed positive correlation with LV myocardial mass index (P = 0.042). It didn't correlate with any other demographic or LV functional cardiac parameters. A good positive correlation was detected between the percentage of DE-MRI and the severity of pressure gradient across LVOT measured by echocardiography (r = 0.69 and P = <0.001). We found a significant correlation between the percentage of DE-MRI in children with HCM and the pressure gradient across LVOT, NYHA classification, and LV myocardial mass. This may help in the further management of those patients, planning for follow-up, and prognosis of the disease.

Reduced exercise capacity in genetic haemochromatosis

BACKGROUND

Many patients with genetic haemochromatosis complain about fatigue and reduced physical capacity. Exercise capacity, however, has not been evaluated in larger series of haemochromatosis patients treated with repeated phlebotomy.

DESIGN AND METHODS

We performed exercise echocardiography in 152 treated haemochromatosis patients (48+/-13 years, 26% women) and 50 healthy blood donors (49+/-13 years, 30% women), who served as controls. Echocardiography was performed at rest and during exercise in a semiupright position on a chair bicycle, starting from 20 W, increasing by 20 W/min. Transmitral early and atrial velocity and isovolumic relaxation time were measured at each step. Ventilatory gas exchange was measured by the breath-to-breath-technique.

RESULTS

Compared with healthy controls, haemochromatosis patients were more obese and less trained. More of them smoked, and 17% had a history of cardiovascular or pulmonary disease. Adjusted for training, the left ventricular function and dimensions at rest did not differ between the groups. During exercise the haemochromatosis patients obtained a significantly lower peak oxygen (O2) uptake (28.1 vs. 34.4 ml/kg per min, P<0.001). In a multiple regression analysis haemochromatosis predicted lower peak O2 uptake independently of significant contributions of sex, age, and height, as well as of systolic blood pressure and log-transformed isovolumic relaxation time at peak exercise, whereas no independent association was found with weight or physical activity (multiple R=0.74, P<0.001). Adding genotype, s-ferritin, prevalence of smoking, or history of cardiopulmonary disease among the covariates in subsequent models did not change the results.

CONCLUSION

Genetic haemochromatosis, even when treated with regular phlebotomy, is associated with lower exercise capacity independently of other covariates of exercise capacity.

β-Blockers and ivabradine differentially affect cardiopulmonary function and left ventricular filling index

OBJECTIVE

Patients with left ventricular (LV) diastolic dysfunction are characterized by exertional dyspnoea. Heart rate (HR) reduction by β-blockers can improve exercise tolerance by prolonging LV filling, but their negative inotropic and lusitropic properties can be detrimental in this disease. We tested the effects of administering ivabradine, a HR-lowering drug without impact on cardiac kinetics that may favorably affect diastolic function.

METHODS

Twenty-four patients with coronary artery disease (CAD) and normal LV ejection fraction on chronic β-blocker therapy were included. NT-proBNP serum levels were determined prior to and after cardiopulmonary exercise. β-Blockers were then replaced by ivabradine and patients were re-tested after 6 weeks. Patients were initially classified as having a low (E/e' ≤ 8; n = 11) or high (E/e' > 8; n = 13) LV filling index.

RESULTS

E/e' significantly decreased during ivabradine therapy in patients with high E/e' (10.7 ± 2.9 vs. 8.9 ± 1.7; p < 0.01), whereas no difference occurred in patients with low E/e' (6.4 ± 0.7 vs. 6.5 ± 1.1; p = ns). With ivabradine, patients with high E/e' had an increased oxygen uptake at the anaerobic threshold (from 10.8 ± 1.4 to 11.8 ± 1.9 ml/min/kg; p < 0.05) and a steeper slope of the initial oxygen pulse curve (from 293 ± 109 to 359 ± 117 µl/beat/kg/W; p < 0.05). Moreover, patients with high E/e' had lower NT-proBNP serum levels at rest (169 ± 207 vs. 126 ± 146 pg/ml; p < 0.05) and after exercise (190 ± 256 vs. 136 ± 162 pg/ml; p < 0.05) during ivabradine therapy.

CONCLUSIONS

In patients with CAD and elevated E/e', switching therapy from β-blockers to ivabradine may cause a reduction in LV filling pressures and an improved stroke volume response to exercise.

Exercise Tolerance and the Post Exercise Diastolic Filling Pattern in Patients With the Resting Impaired Relaxation

Background

In patients with normal LV systolic function, cardiac output increases with exercise mediated by increased stroke volume early in exercise and an increase in heart rate later in exercise. Despite normal LV systolic function, patients who display an impaired relaxation pattern may have a reduced exercise tolerance. We hypothesized that the resting impaired relaxation pattern that persists during exercise results in reduced LV filling volume and reduced exercise tolerance.

Methods

We evaluated consecutive exercise echocardiograms performed at Harper Hospital from 1998-2000 for patients with sinus rhythm, normal resting wall motion and ejection fraction (> 55%), evidence of resting impaired relaxation, and a negative exercise echocardiogram. There were 49 patients fitting the above criteria who were compared with a group of age and sex matched patients (43 patients) with a normal rest and exercise echocardiogram with normal resting transmitral Doppler. Rest and post exercise echocardiography and Doppler parameters were obtained.

Results

Patients in the impaired relaxation group demonstrated shorter exercise times as compared to the normal control group (8.8 ± 1.6 versus 9.7 ± 2.0 minutes, P < 0.001). In patients with normal resting transmitral diastolic filling, there was an increased the extent of atrial contribution to LV filling volume post exercise associated with shortening of isovolumic relaxation. Two patterns were seen in the impaired relaxation group post exercise. In 1 subgroup in which E/A ratio decreased post exercise, exercise duration was reduced (7.4 ± 1.3 minutes, P < 0.001) as compared to the subgroup with E/A increase (9.6 ± 1.2 minutes) post exercise which was similar to normal controls. Forward stepwise regression indicated that exercise time was primarily related to E/A change post exercise for all patient groups (r = 0.625, P = 0.0008). Specifically, this was true for patients with E/A reversal at rest (r = 0.584, P = 0.0028). However, for patients with normal diastolic filling at rest, the diastolic velocity integral was the major predictor (r = 0.695, P < 0.0084).

Conclusion

We conclude that the transmitral Doppler pattern post exercise provides insight into the mechanism of reduced exercise tolerance in some patients with the resting impaired relaxation pattern. Preservation of this pattern post exercise is associated with reduced exercise tolerance.

Prognostic significance of myocardial fibrosis in hypertrophic cardiomyopathy

OBJECTIVES

We investigated the significance of fibrosis detected by late gadolinium enhancement cardiovascular magnetic resonance for the prediction of major clinical events in hypertrophic cardiomyopathy (HCM).

BACKGROUND

The role of myocardial fibrosis in the prediction of sudden death and heart failure in HCM is unclear with a lack of prospective data.

METHODS

We assessed the presence and amount of myocardial fibrosis in HCM patients and prospectively followed them for the development of morbidity and mortality in patients over 3.1 +/- 1.7 years.

RESULTS

Of 217 consecutive HCM patients, 136 (63%) showed fibrosis. Thirty-four of the 136 patients (25%) in the fibrosis group but only 6 of 81 (7.4%) patients without fibrosis reached the combined primary end point of cardiovascular death, unplanned cardiovascular admission, sustained ventricular tachycardia or ventricular fibrillation, or appropriate implantable cardioverter-defibrillator discharge (hazard ratio [HR]: 3.4, p = 0.006). In the fibrosis group, overall risk increased with the extent of fibrosis (HR: 1.18/5% increase, p = 0.008). The risk of unplanned heart failure admissions, deterioration to New York Heart Association functional class III or IV, or heart failure-related death was greater in the fibrosis group (HR: 2.5, p = 0.021), and this risk increased as the extent of fibrosis increased (HR: 1.16/5% increase, p = 0.017). All relationships remained significant after multivariate analysis. The extent of fibrosis and nonsustained ventricular tachycardia were univariate predictors for arrhythmic end points (sustained ventricular tachycardia or ventricular fibrillation, appropriate implantable cardioverter-defibrillator discharge, sudden cardiac death) (HR: 1.30, p = 0.014). Nonsustained ventricular tachycardia remained an independent predictor of arrhythmic end points after multivariate analysis, but the extent of fibrosis did not.

CONCLUSIONS

In patients with HCM, myocardial fibrosis as measured by late gadolinium enhancement cardiovascular magnetic resonance is an independent predictor of adverse outcome. (The Prognostic Significance of Fibrosis Detection in Cardiomyopathy; NCT00930735).

Impact of hypertension on left ventricular hypertrophy regression and exercise capacity in patients operated for aortic valve stenosis

OBJECTIVES

To assess the influence of concomitant hypertension on left ventricular hypertrophy regression and exercise capacity in patients operated for aortic stenosis.

DESIGN

We performed echocardiography 1 week, 6- and 18-month postoperatively in 78 patients, aged 70 (28-86) years, who received Medtronic Hall (33), Biocor (8), Carpentier-Edwards S.A.V. (14) and Freestyle (23) prosthetic valves for severe aortic stenosis. Forty nine patients participated in treadmill tests with ergospirometry at the 6- and 18-month visits.

RESULTS

Left ventricular mass index was comparably reduced in normotensive and hypertensive patients (34 vs. 40 g/m2 after 6 months, and 43 vs. 46 g/m2 after 18 months, ns). In multiple regression analysis, adjusting for baseline left ventricular mass index, larger reduction in left ventricular mass index was associated with younger age and having a Freestyle prosthesis, but not with gender or history of hypertension (multiple R2=0.68, p < 0.05). Exercise capacity assessed as peak oxygen uptake increased from early to late evaluation in normotensive patients (VO2max 24.27 vs. 27.08 ml/kg/min, p < 0.05) while remained unchanged in hypertensive patients (VO2max 22.2 vs. 21.1 ml/kg/min). In multiple regression analysis, higher improvement in exercise capacity was predicted by male gender, younger age and absence of hypertension, while no independent association was found with Freestyle prosthesis (multiple R2 = 0.37, p < 0.05).

CONCLUSIONS

In patients operated for aortic stenosis, concomitant hypertension is associated with lack of improvement in exercise capacity in spite of early left ventricular hypertrophy reduction comparable to what is found in normotensive patients.

Left ventricular diastolic dysfunction in elderly hypertensives: results of the APROS-diadys study

BACKGROUND

A number of patients with chronic heart failure (CHF) have diastolic but not systolic dysfunction. This occurs particularly in the elderly and in hypertension, but the prevalence of diastolic dysfunction in elderly hypertensives without CHF has never been investigated systematically.

METHODS AND RESULTS

The Assessment of PRevalence Observational Study of Diastolic Dysfunction (APROS-diadys) project was a cross-sectional observational study on elderly (age >/= 65 years) hypertensives without systolic dysfunction [left ventricular ejection fraction (LVEF) >/= 45%] consecutively attending hospital outpatient clinics in Italy, in order to establish the prevalence of echocardiographic signs of diastolic dysfunction according to various criteria, and to correlate them with a number of demographic and clinical characteristics. Primary criteria for diastolic dysfunction was an E/A ratio (ratio between transmitral peak velocities of E and A waves) < 0.7 or > 1.5 on echocardiographic Doppler examination. Secondary criteria were: E/A < 0.5 and deceleration time (DT) > 280 ms, or isovolumic relaxation time (IVRT) > 105 ms or pulmonary vein (PV) peak systolic/peak diastolic flow (S/D) ratio > 2.5 or PV atrial retrograde flow (PV A) > 35 cm/s. Throughout Italy, 27 447 patients were screened in 107 clinics, with 24 141 excluded according to protocol. Among the remaining 3336 patients, 754 (22.6%) had signs of CHF. After exclusion of 37 protocol violators, 2545 patients (49.0% men, mean age 70.3 years, 95.4% under antihypertensive treatment) were studied ultrasonographically. Diastolic dysfunction (primary criteria) was found in 649 (25.8%) patients. Multiple logistic regression analysis found age, gender, left ventricular mass, systolic and pulse pressures and midwall shortening fraction as significant covariates. Using secondary criteria, the prevalence of diastolic dysfunction was higher (45.6%), mostly because of IVRT > 105 ms or PVA flow > 35 cm/s.

CONCLUSION

CHF and diastolic dysfunction are highly prevalent in elderly hypertensives attending hospital clinics.

Exercise performance during losartan- or atenolol-based treatment in hypertensive patients with electrocardiographic left ventricular hypertrophy (a LIFE substudy)

The objective of the study was to assess the influence of left ventricular (LV) hypertrophy regression on exercise capacity in hypertensive patients. Doppler echocardiography was performed at rest and during exercise in 51 patients with electrocardiographic LV hypertrophy before and after 1 year of randomized blinded losartan- or atenolol-based antihypertensive treatment. After 1 year, blood pressure was comparably reduced by 32/14 and 27/13 mmHg, respectively, in the losartan and atenolol groups, but the atenolol group had higher mean LV mass index (118 vs 103 g/m2) and lower LV ejection fraction (61% vs 67%) and midwall shortening (15.8% vs 16.8%) (all p<0.05). Resting diastolic Doppler indices remained unchanged and did not differ between the groups. Peak oxygen uptake during exercise was virtually unchanged after 1 year and did not differ between the groups in spite of a lower peak exercise heart rate in atenolol-treated patients. In multivariate analysis, higher peak oxygen uptake at 1 year was associated with lower body mass index, and higher systolic blood pressure and shorter isovolumic relaxation time at peak exercise (multiple R2 = 0.51, p<0.01), while age, gender, heart rate increase during exercise, reduction in LV mass and study treatment did not enter. In conclusion, reduction in blood pressure and LV mass induced by losartan or atenolol treatment was not accompanied by improved exercise capacity after 1 year. The results may be explained by persistent impairment of myocardial relaxation influencing exercise capacity.

Traditional and Color M-Mode Parameters of Left Ventricular Diastolic Function During Low-dose Dobutamine Stress Echocardiography: Relations to Contractility Reserve

BACKGROUND

Cross-sectional studies reported that left ventricular (LV) systolic and diastolic functions are correlated. However, whether changes in wall-motion score index (WMSI) or 2-dimensional ejection fraction (EF) predict changes of Doppler parameters of LV diastolic function is unclear.

METHODS

Patients with known or suspected history of coronary artery disease underwent assessment of LV systolic function (WMSI, EF) and diastolic function at baseline and during stress echocardiography by low-dose dobutamine (LDD) (peak infusion 10 microg/kg/min). Peak velocities of early (E) and late (A) LV filling waves and E wave deceleration time were measured according to standard protocol. E wave propagation rate (EVp) was assessed by color Doppler M-mode across the mitral valve. Tei index was calculated as: (A wave to E wave time - ejection time)/ejection time. Changes at LDD were calculated as: 100 x (value at LDD - value at baseline)/baseline.

RESULTS

The study group comprised 66 patients, mean age 61 +/- 10 years, 80% men. Worse LV systolic function was associated with more severely impaired LV diastolic function both at baseline and at LDD. However, percent change of WMSI and change in EF did not correlate with percent change of EVp and E/E wave propagation rate, but with percent change of Tei index. At LDD, patients with myocardial viability did not show greater percent change of LV diastolic function parameters but significantly lower Tei index.

CONCLUSIONS

In patients with suspected or known coronary artery disease, assessment of diastolic function reserve by LDD stress echocardiography using traditional and color M-mode Doppler may add quantitative information on myocardial function beyond traditional assessment of contractility reserve by WMSI or EF.

Early Target Organ Damage and Its Reversibility: The Heart

Left ventricular hypertrophy (LVH) represents not only an adaptation to increased load, but also a risk factor and a marker of risk of cardiovascular diseases. It may be detected early in the development of the disease by electrocardiography or echocardiography. LVH is often associated to abnormalities of systolic and diastolic function, and its presence clearly predisposes not only to cardiac ischemia and to congestive heart failure, but also to a higher incidence of stroke. A large number of clinical and experimental studies have shown that long-term antihypertensive treatment may be associated with regression of LVH. Long-term antihypertensive treatment is associated with a progressive decrease of LV mass. Differences on reduction of LV mass using different classes of antihypertensive drugs for the same decrease of blood pressure are usually mild, although the effect on cardiac structure and tissue composition are probably not the same. In fact, not only the quantity of left ventricular mass, but also its quality (i.e., collagen content, contractile machinery) should be evaluated and improved by treatment. The incidence of cardiovascular events in hypertensive patients is clearly related to the value of LV mass achieved during treatment; in fact, a reduction in LVH by antihypertensive treatment is associated with improvement in outcome and with decrease of the risk of cardiovascular morbidity and mortality, even independently from changes of other risk factors, including blood pressure. In patients with LVH at baseline, the decrease of LV mass is associated with a number of pathophysiological changes such as 1) improved systolic performance at the midwall, 2) possible improvement of diastolic filling, 3) autonomic nervous system changes toward normalization, 4) possible reduction or ventricular arrhythmias and 5) coronary reserve improvement. All these changes might explain an improvement of clinical prognosis in hypertensive patients. Ongoing studies will more precisely assess the quantitative relation between development or regression of LV mass, improvement of systolic and diastolic function and incidence of cardiovascular events. At present time detection, prevention and reversal of LVH represent a major goal in the management of hypertensive patients.

Relationship between exercise systolic blood pressure and left ventricular geometry in overweight, mildly hypertensive patients

OBJECTIVE

To examine the association between the graded exercise systolic blood pressure (SBP) response and left ventricular (LV) geometric structure in patients with untreated mild hypertension.

PARTICIPANTS

The study included 80 sedentary, overweight patients (43 female and 37 male) with unmedicated high normal blood pressure or stage 1-2 hypertension.

METHODS

An echocardiogram was used to determine LV mass and the relative wall thickness (RWT) in relation to the chamber dimension. Participants performed a maximal graded exercise test, and the SBP was recorded at workloads of 2, 4 and 6 metabolic equivalents and at peak exercise. Separate statistical models were used to determine the influence of LV mass indexed for height(2.7) (LVMIh) and RWT on submaximal exercise SBP and peak exercise SBP, controlling for resting SBP, age, gender, ethnicity and body mass index.

RESULTS

A greater RWT was associated with a higher submaximal SBP level (P = 0.038). Neither LVMIh (P = 0.989) nor the interaction of RWT and LVMIh (P = 0.787) were related to the submaximal SBP. None of the main or interaction effects of RWT and LVMIh were associated with the peak exercise SBP level.

CONCLUSION

Increases in RWT were associated with higher submaximal exercise SBP responses in a sample of overweight, unmedicated hypertensives. These results suggest that RWT is an important determinant of the association between cardiac mass and exercise SBP response.

The Role of Exercise in the Treatment of Cardiovascular Disease Associated with Type 2 Diabetes Mellitus

The role of exercise training in the prevention and treatment of type 2 diabetes mellitus has been studied extensively over the past two decades. Although the primary treatment aim for patients with type 2 diabetes is metabolic control, the morbidity and mortality associated with the disease is more a function of cardiovascular disease. As exercise is associated with favourable reductions in the risk for cardiovascular disease in other high-risk populations, here we explore the role of exercise in the treatment of cardiovascular maladaptations associated with type 2 diabetes. The cardiovascular adaptation to type 2 diabetes is characterised by hypertrophy, stiffening and loss of functional reserve. Clinically, the cardiovascular adaptations to the diabetic state are associated with an increased risk for cardiovascular disease. Functionally, these adaptations have been shown to contribute to a reduced exercise capacity, which may explain the reduced cardiovascular fitness observed in this population. Exercise training is associated with improved exercise capacity in various populations, including type 2 diabetes. Several structural and functional adaptations within the cardiovascular system following exercise training could explain these findings, such as reductions in ventricular and vascular structural hypertrophy and compliance coupled with increased functional reserve. Although these cardiovascular adaptations to aerobic exercise training have been well documented in older populations with similar decrements in cardiovascular fitness and function, they have yet to be examined in patients with type 2 diabetes. For this reason, we contend that exercise training may be an excellent therapeutic adjunct in the treatment of diabetic cardiovascular disease.