Different determinants of exercise capacity in HFpEF compared to HFrEF

BACKGROUND

Quality of life is as important as survival in heart failure (HF) patients. Controversies exist with regards to echocardiographic determinants of exercise capacity in HF, particularly in patients with preserved ejection fraction (HFpEF). The aim of this study was to prospectively examine echocardiographic parameters that correlate and predict functional exercise capacity assessed by 6 min walk test (6-MWT) in patients with HFpEF.

METHODS

In 111 HF patients (mean age 63 ± 10 years, 47% female), an echo-Doppler study and a 6-MWT were performed in the same day. Patients were divided into two groups based on the 6-MWT distance (Group I: ≤ 300 m and Group II: >300 m).

RESULTS

Group I were older (p = 0.008), had higher prevalence of diabetes (p = 0.027), higher baseline heart rate (p = 0.004), larger left atrium - LA (p = 0.001), longer LV filling time - FT (p = 0.019), shorter isovolumic relaxation time (p = 0.037), shorter pulmonary artery acceleration time - PA acceleration time (p = 0.006), lower left atrial lateral wall myocardial velocity (a') (p = 0.018) and lower septal systolic myocardial velocity (s') (p = 0.023), compared with Group II. Patients with HF and reduced EF (HFrEF) had lower hemoglobin (p = 0.007), higher baseline heart rate (p = 0.005), higher NT-ProBNP (p = 0.001), larger LA (p = 0.004), lower septal s', e', a' waves, and septal mitral annular plane systolic excursion (MAPSE), shorter PA acceleration time (p < 0.001 for all), lower lateral MAPSE, higher E/A & E/e', and shorter LVFT (p = 0.001 for all), lower lateral e' (p = 0.009), s' (p = 0.006), right ventricular e' and LA emptying fraction (p = 0.012 for both), compared with HFpEF patients. In multivariate analysis, only LA diameter [2.676 (1.242-5.766), p = 0.012], and diabetes [0.274 (0.084-0.898), p = 0.033] independently predicted poor 6-MWT performance in the group as a whole. In HFrEF, age [1.073 (1.012-1.137), p = 0.018] and LA diameter [3.685 (1.348-10.071), p = 0.011], but in HFpEF, lateral s' [0.295 (0.099-0.882), p = 0.029], and hemoglobin level [0.497 (0.248-0.998), p = 0.049] independently predicted poor 6-MWT performance.

CONCLUSIONS

In HF patients determinants of exercise capacity differ according to severity of overall LV systolic function, with left atrial enlargement in HFrEF and longitudinal systolic shortening in HFpEF as the the main determinants.

Myocardial inotropic reserve: An old twist that constitutes a reliable index in the modern era of heart failure

Current national and international guidelines, including those of the European Society of Cardiology, recognize that the assessment of prognosis should be a part of the standard management for patients with chronic heart failure (CHF). However, these same guidelines recognize the inherent difficulty of this process. A variety of factors contribute to this difficulty, including the varying etiology, frequent co-morbidity and, perhaps most importantly, huge inter-individual variability in the disease progression and outcome. Although CHF is chronic, it is also a condition in which significant proportions of patients experience apparently 'sudden' death, which almost certainly contributes to our difficulty in assessing individual patient prognosis. A useful tool for the risk stratification of heart failure patients is dobutamine stress echocardiography (DSE), which determines the myocardial viability in ischemic cardiomyopathy and myocardial contractile reserve in idiopathic cardiomyopathy.

Exertional dyspnoea in chronic heart failure: the role of the lung and respiratory mechanical factors

Exertional dyspnoea is among the dominant symptoms in patients with chronic heart failure and progresses relentlessly as the disease advances, leading to reduced ability to function and engage in activities of daily living. Effective management of this disabling symptom awaits a better understanding of its underlying physiology.

Cardiovascular factors are believed to play a major role in dyspnoea in heart failure patients. However, despite pharmacological interventions, such as vasodilators or inotropes that improve central haemodynamics, patients with heart failure still complain of exertional dyspnoea. Clearly, dyspnoea is not determined by cardiac factors alone, but likely depends on complex, integrated cardio-pulmonary interactions.

A growing body of evidence suggests that excessively increased ventilatory demand and abnormal “restrictive” constraints on tidal volume expansion with development of critical mechanical limitation of ventilation, contribute to exertional dyspnoea in heart failure. This article will offer new insights into the pathophysiological mechanisms of exertional dyspnoea in patients with chronic heart failure by exploring the potential role of the various constituents of the physiological response to exercise and particularly the role of abnormal ventilatory and respiratory mechanics responses to exercise in the perception of dyspnoea in patients with heart failure.

Long-term outcomes after transcatheter aortic valve implantation: the impact of intraoperative tissue Doppler echocardiography

OBJECTIVES

Transcatheter aortic valve implantation improves survival in patients with severe aortic stenosis who are ineligible for surgical valve replacement; however, not all patients benefit from the procedure. We endeavoured to identify these patients using intraoperative echocardiography and hypothesized that intraoperative left ventricular function in response to the acute afterload reduction during the procedure was related to long-term outcomes.

METHODS

We prospectively included 64 patients who were scheduled for transcatheter aortic valve implantation and divided them into responders and non-responders based on their left ventricular intraoperative responses to the acute afterload reduction after valve deployment. Responders were defined by increases of ≥20% in left ventricular longitudinal peak systolic velocities determined by tissue Doppler echocardiography. All patients were assessed for the following outcomes at 12 months: cardiac mortality, adverse cardiac events, quality of life, New York Heart Association class, N-terminal pro-brain natriuretic peptide (NT-proBNP) and echocardiography.

RESULTS

Thirty-five patients (55%) were classified as responders and 29 patients (45%) as non-responders. Compared with responders, non-responders had higher risks of death (28 vs 9%, respectively, P = 0.04) and cardiac events (66 vs 26%, respectively, P < 0.01) during the 12-month follow-up. Significant long-term improvements in quality of life, NT-proBNP and left ventricular function were observed only in the responders. Preoperative risk stratification, intraoperative handling, aortic gradient and valve area were similar between groups.

CONCLUSIONS

Intraoperative assessment of left ventricular function by tissue Doppler echocardiography predicted long-term outcomes after transcatheter aortic valve implantation. Our results suggest that a preoperative test of myocardial contractile reserve might improve risk stratification and patient selection prior to the procedure.

Intraoperative improvement in left ventricular peak systolic velocity predicts better short-term outcome after transcatheter aortic valve implantation

OBJECTIVES

Left ventricular function is expected to improve after transcatheter aortic valve implantation due to the acute reduction in afterload, but does not occur in all patients. We hypothesized that the immediate intraoperative response in systolic left ventricular longitudinal motion during the procedure could be a predictor of short-term outcome.

METHODS

Sixty-four patients treated with transcatheter aortic valve implantation for severe aortic stenosis were included. Transoesophageal 4- and 2-chamber echocardiograms were obtained immediately prior to and ∼15 min after valve implantation. Patients were defined as responders if their average left ventricular longitudinal peak systolic velocity increased by ≥20% from the preimplantation value and was related to the 3-month outcome.

RESULTS

Thirty-five patients were classified as responders, with an increase in the intraoperative longitudinal peak systolic velocity from an average of 2.2 ± 0.8 to 3.1 ± 1.1 cm/s (P < 0.001); the velocity was unchanged in the remaining 29 patients, who averaged 2.4 ± 1.1 cm/s. There were significantly fewer adverse cardiac events in the responder group at the 3-month follow-up (20 vs 45%, P = 0.03) and the New York Heart Association class was significantly better in the responders compared with non-responders. Responders had a significant reduction in N-terminal probrain natriuretic peptide levels [243 (113-361) vs 163 (64-273), P = 0.004] at the 3-month follow-up, whereas non-responders did not [469 (130-858) vs 289 (157-921), P = 0.48].

CONCLUSIONS

An immediate improvement in the longitudinal peak systolic velocity during the transcatheter aortic valve implantation procedure predicted a better short-term outcome and may be useful in identifying patients who are at risk of a less favourable outcome after transcatheter aortic valve implantation.

Prognostic importance of tissue velocity imaging during exercise echocardiography in patients with systolic heart failure

Resting echocardiography measurements are poor predictors of exercise capacity and symptoms in patients with heart failure (HF). Stress echocardiography may provide additional information and can be expressed using left ventricular ejection fraction (LVEF), or diastolic parameters (E/E'), but LVEF has some major limitations. Systolic annular velocity (S') provides a measure of longitudinal systolic function, which is relatively easy to obtain and shows a good relationship with exercise capacity. The objective of this study was to investigate the relationship among S', E/E' and LVEF obtained during stress echocardiography and both mortality and hospitalisation. A secondary objective was to compare S' measured using a simplified two-wall model. A total of 80 patients with stable HF underwent exercise stress echocardiography and simultaneous cardiopulmonary exercise testing. Volumetric and tissue velocity imaging (TVI) measurements were obtained, as was peak oxygen uptake (VO2 peak). Of the total number of patients, 11 died and 22 required cardiac hospitalisation. S' at peak exertion was a powerful predictor for death and hospitalisation. Cut-off points of 5.3 cm/s for death and 5.7 cm/s for hospitalisation provided optimum sensitivity and specificity. This study suggests that, in patients with systolic HF, S' at peak exertion calculated from the averaged spectral TVI systolic velocity of six myocardial segments, or using a simplified measure of two myocardial segments, is a powerful predictor of future events and stronger than LVEF, diastolic velocities at rest or exercise and VO2 peak. Results indicate that measuring S' during exercise echocardiography might play an important role in understanding the likelihood of adverse clinical outcomes in patients with HF.

Transcatheter aortic valve implantation and intraoperative left ventricular function: a myocardial tissue Doppler imaging study

OBJECTIVE

Transcatheter aortic valve implantation in patients turned down for surgical aortic valve replacement is a high-risk procedure. Severe aortic stenosis is associated with impaired left ventricular longitudinal motion, and myocardial peak systolic velocity is a measure of left ventricular function in these patients. The present study aimed to quantify the acute changes in left ventricular function during the procedure by using myocardial tissue Doppler imaging and transthoracic cardiac output measurements.

DESIGN

Prospective observational study.

SETTING

Tertiary care university hospital.

PARTICIPANTS

40 patients with severe aortic stenosis scheduled for transcatheter aortic valve implantation.

INTERVENTIONS

Transesophageal 4-chamber and 2-chamber echocardiograms were performed immediately before and ~15 minutes after valve implantation. Longitudinal myocardial peak systolic velocity was obtained by tissue Doppler imaging from 8 basal segments and averaged. Cardiac output was measured by the lithium dilution method, and systemic vascular resistance index and stroke volume were calculated.

MEASUREMENTS AND MAIN RESULTS

Longitudinal myocardial peak systolic velocity improved immediately after valve implantation, from -2.3±0.8 to -3.0±1.1 cm/sec (p<0.001); this represented an average increase of 31%±33%. Cardiac output increased from 3.2±0.8 L/min to 3.6±0.9 L/min (15%±33%; p = 0.04). This was due to increased heart rate (59±9 beats/min to 72±12 beats/min; p<0.001) and not to an improved stroke volume. Systemic vascular resistance index was reduced from 2,937±984 dynes*sec/cm(5)/m(2) to 2,436±730 dynes*sec/cm(5)/m(2) (p = 0.003).

CONCLUSION

Intraoperative echocardiography tissue Doppler imaging detected immediate improvement in left ventricular long-axis motion after transcatheter aortic valve implantation. The method provided detailed information not obtainable by routine hemodynamic monitoring.

Reference values of the mitral annular peak systolic velocity (Sm) in 690 healthy pediatric patients, calculation of Z-score values, and comparison to the mitral annular Plane systolic excursion (MAPSE)

BACKGROUND

The mitral annular peak systolic velocity (Sm) is an echocardiographic measurement using tissue Doppler imaging to assess longitudinal left ventricular (LV) systolic function in children and adults. We determined growth-related changes in Sm to establish reference values for the entire pediatric age group.

METHODS AND RESULTS

A prospective study was conducted in a group of 690 healthy pediatric patients (age: 1 day-18 years). We determined the effects of age, sex, and body surface area (BSA) on the Sm values. Regression analysis was used to estimate Sm from age, BSA, and sex. In addition, a correlation of normal Sm with normal age-matched values of the M-mode parameter mitral annular plane systolic excursion (MAPSE) was measured. The Sm ranged from a mean of 5.8 cm/sec (Z-score ±2: 3.6-8.0 cm/sec) in the newborn to 11.8 cm/sec (Z-score ±2: 8.5-15.1 cm/sec) in the 18-year-old adolescent. The Sm values showed a positive correlation with age and BSA with a nonlinear course. There was no significant difference in Sm values between females and males. A significant correlation was found between Sm and MAPSE values.

CONCLUSION

Z-scores of Sm values were calculated and percentile charts were established to serve as reference data in patients with congenital heart diseases.

Gender related predictors of limited exercise capacity in heart failure

AIM

The aim of this study was to investigate the impact of gender on the prediction of limited exercise capacity in heart failure (HF) patients assessed by 6 minute walk test (6-MWT).

METHODS

In 147 HF patients (mean age 61 ± 11 years, 50.3% male), a 6-MWT and a Doppler echocardiographic study were performed in the same day. Conventional cardiac measurements were obtained and global LV dyssynchrony was indirectly assessed using total isovolumic time - t-IVT [in s/min; calculated as: 60 - (total ejection time - total filling time)] and Tei index (t-IVT/ejection time). Patients were divided into two groups according to gender, which were again divided into two subgroups based on the 6-MWT distance (Group I: ≤ 300 m, and Group II: > 300 m).

RESULTS

Female patients were younger (p = 0.02), and had higher left ventricular (LV) ejection fraction - EF (p = 0.007) but with similar 6-MWT distance to male patients (p = 68). Group I male patients had lower hemoglobin level (p = 0.02) and lower EF (p = 0.03), compared with Group II, but none of the clinical or echocardiographic variables differed between groups in female patients. In multivariate analysis, only t-IVT [0.699 (0.552-0.886), p = 0.003], and LV EF [0.908 (0.835-0.987), p = 0.02] in males, and NYHA functional class [4.439 (2.213-16.24), p = 0.02] in females independently predicted poor 6-MWT distance (< 300 m).

CONCLUSION

Despite similar limited exercise capacity, gender determines the pattern of underlying cardiac disturbances; ventricular dysfunction in males and subjective NYHA class in female heart failure patients.

Left ventricular markers of global dyssynchrony predict limited exercise capacity in heart failure, but not in patients with preserved ejection fraction

BACKGROUND

The aim of this study was to prospectively examine echocardiographic parameters that correlate and predict functional capacity assessed by 6 min walk test (6-MWT) in patients with heart failure (HF), irrespective of ejection fraction (EF).

METHODS

In 147 HF patients (mean age 61 ± 11 years, 50.3% male), a 6-MWT and an echo-Doppler study were performed in the same day. Global LV dyssynchrony was indirectly assessed by total isovolumic time - t-IVT [in s/min; calculated as: 60 - (total ejection time + total filling time)], and Tei index (t-IVT/ejection time). Patients were divided into two groups based on the 6-MWT distance (Group I: ≤ 300 m and Group II: >300 m), and also in two groups according to EF (Group A: LVEF ≥ 45% and Group B: LVEF < 45%).

RESULTS

In the cohort of patients as a whole, the 6-MWT correlated with t-IVT (r = -0.49, p < 0.001) and Tei index (r = -0.43, p < 0.001) but not with any of the other clinical or echocardiographic parameters. Group I had lower hemoglobin level (p = 0.02), lower EF (p = 0.003), larger left atrium (p = 0.02), thicker interventricular septum (p = 0.02), lower A wave (p = 0.01) and lateral wall late diastolic myocardial velocity a' (p = 0.047), longer isovolumic relaxation time (r = 0.003) and longer t-IVT (p = 0.03), compared with Group II. In the patients cohort as a whole, only t-IVT ratio [1.257 (1.071-1.476), p = 0.005], LV EF [0.947 (0.903-0.993), p = 0.02], and E/A ratio [0.553 (0.315-0.972), p = 0.04] independently predicted poor 6-MWT performance (<300 m) in multivariate analysis. None of the echocardiographic measurements predicted exercise tolerance in HFpEF.

CONCLUSION

In patients with HF, the limited exercise capacity, assessed by 6-MWT, is related mostly to severity of global LV dyssynchrony, more than EF or raised filling pressures. The lack of exercise predictors in HFpEF reflects its multifactorial pathophysiology.