Myocardial Contractile Reserve by Dobutamine Stress Echocardiography Predicts Improvement in Ejection Fraction With β-Blockade in Patients With Heart Failure

The Utility of Low-Dose-Dobutamine Stress Echocardiography in Patients with Heart Failure with Reduced Ejection Fraction: An Update

Despite significant advancements in medical therapy, heart failure with reduced ejection fraction (HFrEF) continues to be a significant cause of death and disability. Reversible ischaemic left ventricular dysfunction due to viable myocardium is one such contributing factor. In these cases, coronary revascularization has shown promise in improving left ventricular function and prognosis. For patients with HFrEF and wide QRS, cardiac resynchronization therapy (CRT) is an effective option to address electromechanical dyssynchrony. However, approximately 30% of patients do not respond positively to CRT, highlighting the need to refine candidate selection for this treatment. In some patients with reduced HFrEF, there is a condition known as classical low-flow, low-gradient aortic stenosis (AS) that may be observed. This condition is characterized by a low transaortic flow, which leads to reductions in both the transaortic mean gradient and aortic valve area. Decision-making regarding revascularization, CRT, and pharmacological treatment play a crucial role in managing HFrEF. Cardiac imaging can be valuable in guiding decision-making processes and assessing the prognosis of patients with HFrEF. Among the imaging modalities, dobutamine stress echocardiography has come a long way in establishing itself as a feasible, safe, effective, relatively cheap non-invasive technique. The aim of this review is to explore the current literature on the utility of low-dose stress echocardiography in diagnosing and prognosticating patients with HFrEF.

IP3 receptor orchestrates maladaptive vascular responses in heart failure

Patients with heart failure (HF) have augmented vascular tone, which increases cardiac workload, impairing ventricular output and promoting further myocardial dysfunction. The molecular mechanisms underlying the maladaptive vascular responses observed in HF are not fully understood. Vascular smooth muscle cells (VSMCs) control vasoconstriction via a Ca2+-dependent process, in which the type 1 inositol 1,4,5-trisphosphate receptor (IP3R1) on the sarcoplasmic reticulum (SR) plays a major role. To dissect the mechanistic contribution of intracellular Ca2+ release to the increased vascular tone observed in HF, we analyzed the remodeling of IP3R1 in aortic tissues from patients with HF and from controls. VSMC IP3R1 channels from patients with HF and HF mice were hyperphosphorylated by both serine and tyrosine kinases. VSMCs isolated from IP3R1VSMC-/- mice exhibited blunted Ca2+ responses to angiotensin II (ATII) and norepinephrine compared with control VSMCs. IP3R1VSMC-/- mice displayed significantly reduced responses to ATII, both in vivo and ex vivo. HF IP3R1VSMC-/- mice developed significantly less afterload compared with HF IP3R1fl/fl mice and exhibited significantly attenuated progression toward decompensated HF and reduced interstitial fibrosis. Ca2+-dependent phosphorylation of the MLC by MLCK activated VSMC contraction. MLC phosphorylation was markedly increased in VSMCs from patients with HF and HF mice but reduced in VSMCs from HF IP3R1VSMC-/- mice and HF WT mice treated with ML-7. Taken together, our data indicate that VSMC IP3R1 is a major effector of increased vascular tone, which contributes to increased cardiac afterload and decompensation in HF.

Left ventricular contractile reserve as a determinant of adverse clinical outcomes: a systematic review

An abnormal left ventricular contractile reserve is often seen in patients undergoing stress echocardiogram and may indicate the presence of obstructive coronary artery disease. The techniques and indexes used to identify abnormal left ventricular contractile response and its prognostic value in the absence of known causes has not been well studied. To describe the characteristics and clinical outcomes associated with an abnormal left ventricular contractile response, we performed a systematic review that identified 27 eligible studies. A diverse range of indices were utilised to measure left ventricular contractile reserve, most commonly Δleft ventricular ejection fraction in 11 studies. Dobutamine stress echocardiogram was the most commonly performed modality (19 studies) followed by exercise stress echocardiogram (4 studies), dipyridamole stress echocardiogram (2 studies), invasive hemodynamic measurement (1 study) and dobutamine stress magnetic resonance imaging (1 study). All but one study demonstrated a significant association between the absence of left ventricular contractile reserve and increased rate of cardiovascular events, cardiac death and all-cause mortality.

Beta-blockers and inhibitors of the renin-angiotensin aldosterone system for chronic heart failure with preserved ejection fraction

BACKGROUND

Beta-blockers and inhibitors of the renin-angiotensin-aldosterone system improve survival and reduce morbidity in people with heart failure with reduced left ventricular ejection fraction (LVEF); a review of the evidence is required to determine whether these treatments are beneficial for people with heart failure with preserved ejection fraction (HFpEF).

OBJECTIVES

To assess the effects of beta-blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, angiotensin receptor neprilysin inhibitors, and mineralocorticoid receptor antagonists in people with HFpEF.

SEARCH METHODS

We updated searches of CENTRAL, MEDLINE, Embase, and one clinical trial register on 14 May 2020 to identify eligible studies, with no language or date restrictions. We checked references from trial reports and review articles for additional studies.  SELECTION CRITERIA: We included randomised controlled trials with a parallel group design, enrolling adults with HFpEF, defined by LVEF greater than 40%.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included 41 randomised controlled trials (231 reports), totalling 23,492 participants across all comparisons. The risk of bias was frequently unclear and only five studies had a low risk of bias in all domains. Beta-blockers (BBs) We included 10 studies (3087 participants) investigating BBs. Five studies used a placebo comparator and in five the comparator was usual care. The mean age of participants ranged from 30 years to 81 years. A possible reduction in cardiovascular mortality was observed (risk ratio (RR) 0.78, 95% confidence interval (CI) 0.62 to 0.99; number needed to treat for an additional benefit (NNTB) 25; 1046 participants; three studies), however, the certainty of evidence was low. There may be little to no effect on all-cause mortality (RR 0.82, 95% CI 0.67 to 1.00; 1105 participants; four studies; low-certainty evidence). The effects on heart failure hospitalisation, hyperkalaemia, and quality of life remain uncertain. Mineralocorticoid receptor antagonists (MRAs) We included 13 studies (4459 participants) investigating MRA. Eight studies used a placebo comparator and in five the comparator was usual care. The mean age of participants ranged from 54.5 to 80 years. Pooled analysis indicated that MRA treatment probably reduces heart failure hospitalisation (RR 0.82, 95% CI 0.69 to 0.98; NNTB = 41; 3714 participants; three studies; moderate-certainty evidence). However, MRA treatment probably has little or no effect on all-cause mortality (RR 0.91, 95% CI 0.78 to 1.06; 4207 participants; five studies; moderate-certainty evidence) and cardiovascular mortality (RR 0.90, 95% CI 0.74 to 1.11; 4070 participants; three studies; moderate-certainty evidence). MRA treatment may have little or no effect on quality of life measures (mean difference (MD) 0.84, 95% CI -2.30 to 3.98; 511 participants; three studies; low-certainty evidence). MRA treatment was associated with a higher risk of hyperkalaemia (RR 2.11, 95% CI 1.77 to 2.51; number needed to treat for an additional harmful outcome (NNTH) = 11; 4291 participants; six studies; high-certainty evidence). Angiotensin-converting enzyme inhibitors (ACEIs) We included eight studies (2061 participants) investigating ACEIs. Three studies used a placebo comparator and in five the comparator was usual care. The mean age of participants ranged from 70 to 82 years. Pooled analyses with moderate-certainty evidence suggest that ACEI treatment likely has little or no effect on cardiovascular mortality (RR 0.93, 95% CI 0.61 to 1.42; 945 participants; two studies), all-cause mortality (RR 1.04, 95% CI 0.75 to 1.45; 1187 participants; five studies) and heart failure hospitalisation (RR 0.86, 95% CI 0.64 to 1.15; 1019 participants; three studies), and may result in little or no effect on the quality of life (MD -0.09, 95% CI -3.66 to 3.48; 154 participants; two studies; low-certainty evidence). The effects on hyperkalaemia remain uncertain. Angiotensin receptor blockers (ARBs) Eight studies (8755 participants) investigating ARBs were included. Five studies used a placebo comparator and in three the comparator was usual care. The mean age of participants ranged from 61 to 75 years. Pooled analyses with high certainty of evidence suggest that ARB treatment has little or no effect on cardiovascular mortality (RR 1.02, 95% 0.90 to 1.14; 7254 participants; three studies), all-cause mortality (RR 1.01, 95% CI 0.92 to 1.11; 7964 participants; four studies), heart failure hospitalisation (RR 0.92, 95% CI 0.83 to 1.02; 7254 participants; three studies), and quality of life (MD 0.41, 95% CI -0.86 to 1.67; 3117 participants; three studies). ARB was associated with a higher risk of hyperkalaemia (RR 1.88, 95% CI 1.07 to 3.33; 7148 participants; two studies; high-certainty evidence). Angiotensin receptor neprilysin inhibitors (ARNIs) Three studies (7702 participants) investigating ARNIs were included. Two studies used ARBs as the comparator and one used standardised medical therapy, based on participants' established treatments at enrolment. The mean age of participants ranged from 71 to 73 years. Results suggest that ARNIs may have little or no effect on cardiovascular mortality (RR 0.96, 95% CI 0.79 to 1.15; 4796 participants; one study; moderate-certainty evidence), all-cause mortality (RR 0.97, 95% CI 0.84 to 1.11; 7663 participants; three studies; high-certainty evidence), or quality of life (high-certainty evidence). However, ARNI treatment may result in a slight reduction in heart failure hospitalisation, compared to usual care (RR 0.89, 95% CI 0.80 to 1.00; 7362 participants; two studies; moderate-certainty evidence). ARNI treatment was associated with a reduced risk of hyperkalaemia compared with valsartan (RR 0.88, 95% CI 0.77 to 1.01; 5054 participants; two studies; moderate-certainty evidence).

AUTHORS' CONCLUSIONS

There is evidence that MRA and ARNI treatment in HFpEF probably reduces heart failure hospitalisation but probably has little or no effect on cardiovascular mortality and quality of life. BB treatment may reduce the risk of cardiovascular mortality, however, further trials are needed. The current evidence for BBs, ACEIs, and ARBs is limited and does not support their use in HFpEF in the absence of an alternative indication. Although MRAs and ARNIs are probably effective at reducing the risk of heart failure hospitalisation, the treatment effect sizes are modest. There is a need for improved approaches to patient stratification to identify the subgroup of patients who are most likely to benefit from MRAs and ARNIs, as well as for an improved understanding of disease biology, and for new therapeutic approaches.

Contemporary Outcomes in Low-Gradient Aortic Stenosis Patients Who Underwent Dobutamine Stress Echocardiography

Background

Detection of flow reserve (FR) by dobutamine stress echocardiography is used for risk stratification in low‐gradient aortic stenosis (AS). Prognostic significance of dobutamine stress echocardiography in the transcatheter aortic valve replacement era is unclear. We aimed to assess the current relevance of FR.

Methods and Results

We studied 235 patients with low‐gradient severe AS (rest aortic valve area ≤1.0 cm² or indexed aortic valve area ≤0.60 cm²/m²; mean aortic valve gradient <40 mm Hg) and left ventricular ejection fraction <50%) with dobutamine stress echocardiography done September 2010 through July 2016. FR was defined by ≥20% stroke volume increase. We diagnosed “true‐severe AS” if peak aortic valve velocity ≥4 m/s occurred with aortic valve area ≤1.0 cm² (or indexed aortic valve area ≤0.6 cm²/m²). At a median time of 51 days, 128 patients underwent aortic valve replacement,either surgical aortic valve replacement (n=42) or transcatheter aortic valve replacement (n=86). FR was observed in 138 patients, while 86 patients had true‐severe AS. During median follow‐up of 2.3 years, 138 patients died. In a multivariable model, aortic valve replacement (hazard ratio 0.41, 95% CI: 0.29–0.58, P <0.001) and lower Society of Thoracic Surgeons score (hazard ratio 1.06, 95% CI: 1.04–1.09, P<0.001) were associated with better survival, while FR was not predictive. aortic valve replacement was associated with survival regardless of the presence or absence of FR or AS severity stratification.

Conclusions

In low‐gradient AS with reduced ejection fraction, FR or AS severity stratification by dobutamine stress echocardiography was not associated with survival. Aortic valve replacement was associated with better survival in low‐gradient AS independent of FR.

See Editorial by Annabi et al

The Utility of Cardiac Reserve for the Early Detection of Cancer Treatment-Related Cardiac Dysfunction: A Comprehensive Overview

With progressive advancements in cancer detection and treatment, cancer-specific survival has improved dramatically over the past decades. Consequently, long-term health outcomes are increasingly defined by comorbidities such as cardiovascular disease. Importantly, a number of well-established and emerging cancer treatments have been associated with varying degrees of cardiovascular injury that may not emerge until years following the completion of cancer treatment. Of particular concern is the development of cancer treatment related cardiac dysfunction (CTRCD) which is associated with an increased risk of heart failure and high risk of morbidity and mortality. Early detection of CTRCD appears critical for preventing long-term cardiovascular morbidity in cancer survivors. However, current clinical standards for the identification of CTRCD rely on assessments of cardiac function in the resting state. This provides incomplete information about the heart's reserve capacity and may reduce the sensitivity for detecting sub-clinical myocardial injury. Advances in non-invasive imaging techniques have enabled cardiac function to be quantified during exercise thereby providing a novel means of identifying early cardiac dysfunction that has proved useful in several cardiovascular pathologies. The purpose of this narrative review is (1) to discuss the different non-invasive imaging techniques that can be used for quantifying different aspects of cardiac reserve; (2) discuss the findings from studies of cancer patients that have measured cardiac reserve as a marker of CTRCD; and (3) highlight the future directions important knowledge gaps that need to be addressed for cardiac reserve to be effectively integrated into routine monitoring for cancer patients exposed to cardiotoxic therapies.

Pharmacological interventions for heart failure in people with chronic kidney disease

BACKGROUND

Approximately half of people with heart failure have chronic kidney disease (CKD). Pharmacological interventions for heart failure in people with CKD have the potential to reduce death (any cause) or hospitalisations for decompensated heart failure. However, these interventions are of uncertain benefit and may increase the risk of harm, such as hypotension and electrolyte abnormalities, in those with CKD.

OBJECTIVES

This review aims to look at the benefits and harms of pharmacological interventions for HF (i.e., antihypertensive agents, inotropes, and agents that may improve the heart performance indirectly) in people with HF and CKD.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies through 12 September 2019 in consultation with an Information Specialist and using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We included randomised controlled trials of any pharmacological intervention for acute or chronic heart failure, among people of any age with chronic kidney disease of at least three months duration.

DATA COLLECTION AND ANALYSIS

Two authors independently screened the records to identify eligible studies and extracted data on the following dichotomous outcomes: death, hospitalisations, worsening heart failure, worsening kidney function, hyperkalaemia, and hypotension. We used random effects meta-analysis to estimate treatment effects, which we expressed as a risk ratio (RR) with 95% confidence intervals (CI). We assessed the risk of bias using the Cochrane tool. We applied the GRADE methodology to rate the certainty of evidence.

MAIN RESULTS

One hundred and twelve studies met our selection criteria: 15 were studies of adults with CKD; 16 studies were conducted in the general population but provided subgroup data for people with CKD; and 81 studies included individuals with CKD, however, data for this subgroup were not provided. The risk of bias in all 112 studies was frequently high or unclear. Of the 31 studies (23,762 participants) with data on CKD patients, follow-up ranged from three months to five years, and study size ranged from 16 to 2916 participants. In total, 26 studies (19,612 participants) reported disaggregated and extractable data on at least one outcome of interest for our review and were included in our meta-analyses. In acute heart failure, the effects of adenosine A1-receptor antagonists, dopamine, nesiritide, or serelaxin on death, hospitalisations, worsening heart failure or kidney function, hyperkalaemia, hypotension or quality of life were uncertain due to sparse data or were not reported. In chronic heart failure, the effects of angiotensin-converting enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB) (4 studies, 5003 participants: RR 0.85, 95% CI 0.70 to 1.02; I2 = 78%; low certainty evidence), aldosterone antagonists (2 studies, 34 participants: RR 0.61 95% CI 0.06 to 6.59; very low certainty evidence), and vasopressin receptor antagonists (RR 1.26, 95% CI 0.55 to 2.89; 2 studies, 1840 participants; low certainty evidence) on death (any cause) were uncertain. Treatment with beta-blockers may reduce the risk of death (any cause) (4 studies, 3136 participants: RR 0.69, 95% CI 0.60 to 0.79; I2 = 0%; moderate certainty evidence). Treatment with ACEi or ARB (2 studies, 1368 participants: RR 0.90, 95% CI 0.43 to 1.90; I2 = 97%; very low certainty evidence) had uncertain effects on hospitalisation for heart failure, as treatment estimates were consistent with either benefit or harm. Treatment with beta-blockers may decrease hospitalisation for heart failure (3 studies, 2287 participants: RR 0.67, 95% CI 0.43 to 1.05; I2 = 87%; low certainty evidence). Aldosterone antagonists may increase the risk of hyperkalaemia compared to placebo or no treatment (3 studies, 826 participants: RR 2.91, 95% CI 2.03 to 4.17; I2 = 0%; low certainty evidence). Renin inhibitors had uncertain risks of hyperkalaemia (2 studies, 142 participants: RR 0.86, 95% CI 0.49 to 1.49; I2 = 0%; very low certainty). We were unable to estimate whether treatment with sinus node inhibitors affects the risk of hyperkalaemia, as there were few studies and meta-analysis was not possible. Hyperkalaemia was not reported for the CKD subgroup in studies investigating other therapies. The effects of ACEi or ARB, or aldosterone antagonists on worsening heart failure or kidney function, hypotension, or quality of life were uncertain due to sparse data or were not reported. Effects of anti-arrhythmic agents, digoxin, phosphodiesterase inhibitors, renin inhibitors, sinus node inhibitors, vasodilators, and vasopressin receptor antagonists were very uncertain due to the paucity of studies.

AUTHORS' CONCLUSIONS

The effects of pharmacological interventions for heart failure in people with CKD are uncertain and there is insufficient evidence to inform clinical practice. Study data for treatment outcomes in patients with heart failure and CKD are sparse despite the potential impact of kidney impairment on the benefits and harms of treatment. Future research aimed at analysing existing data in general population HF studies to explore the effect in subgroups of patients with CKD, considering stage of disease, may yield valuable insights for the management of people with HF and CKD.

Stress ECHO beyond coronary artery disease. Is it the holy grail of cardiovascular imaging?

Stress echocardiography (SE) is a very useful method in clinical practice, because it offers important information of both the patient's functional status and hemodynamic changes during stress. Therefore, SE provides strong diagnostic and prognostic data in a wide spectrum of cardiovascular diseases. This review summarizes the clinical applications of SE in conditions beyond coronary artery disease (CAD) and highlights practical recommendations and key issues for each condition that need further investigation. SE is an established method for the evaluation of symptomatic and asymptomatic patients with valvular heart disease (VHD) and cardiomyopathies, and provides important information regarding prognosis and management of patients with congenital heart disease, pulmonary hypertension or diastolic dysfunction. Moreover, when one or multiple VHD and cardiomyopathy or CAD coexist in one patient, SE is a very useful clinical tool for the evaluation of etiology and symptomatology.

Left ventricular function during exercise in trained pre-adolescent soccer players

It is unclear, what the underlying cardiovascular mechanisms are that give rise to the high level of aerobic fitness seen in youth soccer players. The aim of the study was to evaluate global and regional markers of systolic and diastolic function in a group of pre-adolescent soccer players during an incremental exercise test. Twenty-two, male soccer players (SP) from two professional soccer clubs (age: 12.0 ± 0.3 years) volunteered for the study. Fifteen recreationally active boys (CON), of similar age (age: 11.7 ± 0.2 years) were also recruited. All boys underwent a cycle ergometer test to exhaustion. Cardiac dimensions were determined using M-mode echocardiography. During submaximal and maximal exercise, continuous-wave Doppler ultrasound techniques were used to derive stroke volume (SVIndex). Tissue-Doppler imaging was used to quantify systolic (S'adj) and diastolic function (E; E'adj and E/E') at rest and both submaximal and maximal exercise intensities. Speckle tracking echocardiography was used to determine peak longitudinal ε at submaximal exercise intensities. SP demonstrated significantly (P ≤ 0.05) greater peak VO₂ values than CON (SP: 48.0 ± 5.0 vs CON: 40.1 ± 7.5 mL/kg/min). Allometrically scaled to body surface area left ventricular end-diastolic volume (LVEDV) was larger (P ≤ 0.05) in the SP (51.3 ± 9.0) compared to CON (44.6 ± 5.8 mL·BSA^1.5 ). At the same relative, submaximal exercise intensities, the SP demonstrated greater SVIndex, cardiac output (QIndex), and E. No differences were noted for peak longitudinal ε during submaximal exercise. Factors that augment pre-load and LV volume appear to determine the superior aerobic fitness seen in the soccer players.

Left ventricular ejection fraction as therapeutic target: is it the ideal marker?

Heart failure (HF) consists the fastest growing clinical cardiac disease. HF patients are categorized on the basis of underlying left ventricular ejection fraction (LVEF) into HF with preserved EF (HFpEF), reduced LVEF (HFrEF), and mid-range LVEF (HFmrEF). While LVEF is the most commonly used surrogate marker of left ventricular (LV) systolic function, the implementation of two-dimensional echocardiography in estimating this parameter imposes certain caveats on current HF classification. Most importantly, LVEF could fluctuate in repeated measurements or even recover after treatment, thus blunting the borders between proposed categories of HF and enabling upward classification of patients. Under this prism, we sought to summarize possible procedures to improve systolic function in patients with HFrEF either naturally or by the means of pharmacologic and non-pharmacologic treatment and devices. Therefore, we reviewed established pharmacotherapy, including beta-blockers, inhibitors of renin-angiotensin-aldosterone axis, statins, and digoxin as well as novel treatments like sacubitril-valsartan, ranolazine, and ivabradine. In addition, we assessed evidence in favor of cardiac resynchronization therapy and exercise training programs. Finally, innovative therapeutic strategies, including stem cells, xanthine oxidase inhibitors, antibiotic regimens, and omega-3 polyunsaturated fatty acids, were also taken into consideration. We concluded that LVEF is subject to changes in HF after intervention and besides the aforementioned HFrEF, HFpEF, and HFmrEF categories, a new entity of HF patients with recovered LVEF should be acknowledged. An improved global and refined LV function assessment by sophisticated imaging modalities and circulating biomarkers is expected to render HF classification more accurate and indicate patients with viable-yet dysfunctional-myocardium and favorable characteristics as the ideal candidates for LVEF recovery by individualized HF therapy.

Beta-blockers and inhibitors of the renin-angiotensin aldosterone system for chronic heart failure with preserved ejection fraction

BACKGROUND

Beta-blockers and inhibitors of the renin-angiotensin aldosterone system improve survival and reduce morbidity in people with heart failure with reduced left ventricular ejection fraction. There is uncertainty whether these treatments are beneficial for people with heart failure with preserved ejection fraction and a comprehensive review of the evidence is required.

OBJECTIVES

To assess the effects of beta-blockers, angiotensin converting enzyme inhibitors, angiotensin receptor blockers, angiotensin receptor neprilysin inhibitors, and mineralocorticoid receptor antagonists in people with heart failure with preserved ejection fraction.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase and two clinical trial registries on 25 July 2017 to identify eligible studies. Reference lists from primary studies and review articles were checked for additional studies. There were no language or date restrictions.

SELECTION CRITERIA

We included randomised controlled trials with a parallel group design enrolling adult participants with heart failure with preserved ejection fraction, defined by a left ventricular ejection fraction of greater than 40 percent.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies for inclusion and extracted data. The outcomes assessed included cardiovascular mortality, heart failure hospitalisation, hyperkalaemia, all-cause mortality and quality of life. Risk ratios (RR) and, where possible, hazard ratios (HR) were calculated for dichotomous outcomes. For continuous data, mean difference (MD) or standardised mean difference (SMD) were calculated. We contacted trialists where neccessary to obtain missing data.

MAIN RESULTS

37 randomised controlled trials (207 reports) were included across all comparisons with a total of 18,311 participants.Ten studies (3087 participants) investigating beta-blockers (BB) were included. A pooled analysis indicated a reduction in cardiovascular mortality (15% of participants in the intervention arm versus 19% in the control arm; RR 0.78; 95% confidence interval (CI) 0.62 to 0.99; number needed to treat to benefit (NNTB) 25; 1046 participants; 3 studies). However, the quality of evidence was low and no effect on cardiovascular mortality was observed when the analysis was limited to studies with a low risk of bias (RR 0.81; 95% CI 0.50 to 1.29; 643 participants; 1 study). There was no effect on all-cause mortality, heart failure hospitalisation or quality of life measures, however there is uncertainty about these effects given the limited evidence available.12 studies (4408 participants) investigating mineralocorticoid receptor antagonists (MRA) were included with the quality of evidence assessed as moderate. MRA treatment reduced heart failure hospitalisation (11% of participants in the intervention arm versus 14% in the control arm; RR 0.82; 95% CI 0.69 to 0.98; NNTB 41; 3714 participants; 3 studies; moderate-quality evidence) however, little or no effect on all-cause and cardiovascular mortality and quality of life measures was observed. MRA treatment was associated with a greater risk of hyperkalaemia (16% of participants in the intervention group versus 8% in the control group; RR 2.11; 95% CI 1.77 to 2.51; 4291 participants; 6 studies; high-quality evidence).Eight studies (2061 participants) investigating angiotensin converting enzyme inhibitors (ACEI) were included with the overall quality of evidence assessed as moderate. The evidence suggested that ACEI treatment likely has little or no effect on cardiovascular mortality, all-cause mortality, heart failure hospitalisation, or quality of life. Data for the effect of ACEI on hyperkalaemia were only available from one of the included studies.Eight studies (8755 participants) investigating angiotensin receptor blockers (ARB) were included with the overall quality of evidence assessed as high. The evidence suggested that treatment with ARB has little or no effect on cardiovascular mortality, all-cause mortality, heart failure hospitalisation, or quality of life. ARB was associated with an increased risk of hyperkalaemia (0.9% of participants in the intervention group versus 0.5% in the control group; RR 1.88; 95% CI 1.07 to 3.33; 7148 participants; 2 studies; high-quality evidence).We identified a single ongoing placebo-controlled study investigating the effect of angiotensin receptor neprilysin inhibitors (ARNI) in people with heart failure with preserved ejection fraction.

AUTHORS' CONCLUSIONS

There is evidence that MRA treatment reduces heart failure hospitalisation in heart failure with preserverd ejection fraction, however the effects on mortality related outcomes and quality of life remain unclear. The available evidence for beta-blockers, ACEI, ARB and ARNI is limited and it remains uncertain whether these treatments have a role in the treatment of HFpEF in the absence of an alternative indication for their use. This comprehensive review highlights a persistent gap in the evidence that is currently being addressed through several large ongoing clinical trials.

Myocardial contractile reserve predicts left ventricular reverse remodeling and cardiac events in dilated cardiomyopathy

BACKGROUND

Catecholamine sensitivity estimated using a dobutamine stress test (DST) is recognized as a measure of the beta-adrenergic myocardial contractile reserve, which is involved with left ventricular reverse remodeling (LV-RR). We investigated whether the prognostic ability of the DST for LV-RR could predict cardiac events.

METHODS

There was a total of 192 enrolled patients with dilated cardiomyopathy (DCM). DCM was defined as a LV ejection fraction (LV-EF) ≤45% and LV end-diastolic dimension (LVDd) ≥55mm. One hundred patients were subjected to micromanometer-based measurement of the maximal first derivative of LV pressure (LVdP/dt_max), an index of LV contractility, at baseline and following the infusion of dobutamine (10μg/kg/min) via a pigtail catheter. Percentage changes in LVdP/dt_max from the baseline to peak values under dobutamine stress (ΔLVdP/dt_max) were also calculated. After excluding 17 patients who received cardiac resynchronization therapy within 3 months of undergoing DST (n=15) and who did not receive follow-up echocardiography (n=2), 83 patients were enrolled (52.5±12.3 years).

RESULTS

During the follow-up period (4.7±2.6 years), LV-RR was recognized in 49 of 83 patients (59.0%). A multivariate logistic regression analysis revealed that ΔLVdP/dt_max (hazard ratio: 1.024, p=0.007) and the symptom duration (hazard ratio: 0.977, p=0.003) were independent predictors of LV-RR. A receiver operating characteristic curve analysis revealed a ΔLVdP/dt_max cut-off value of 75.1% for LV-RR and a significantly lower cardiac event rate in the ΔLVdP/dt_max≥75.1% group (p=0.045).

CONCLUSIONS

ΔLVdP/dt_max estimated using DST was a useful predictor of LV-RR and cardiac events in patients with DCM.

Bucindolol improves right ventricle function in rats with pulmonary arterial hypertension through the reversal of autonomic imbalance

Pulmonary arterial hypertension (PAH) is characterised by an elevation in afterload imposed on the right ventricle (RV), leading to hypertrophy and failure. The autonomic nervous system (ANS) plays a key role in the progression to heart failure, and the use of beta-blockers attenuates this process. The aim of this study was to verify the role of bucindolol, aβ1-, β2- and α1-blocker, on the ANS, and its association with RV function in rats with PAH. Male Wistar rats were divided into four groups: control, monocrotaline, control+bucindolol, and monocrotaline+bucindolol. PAH was induced by a single intraperitoneal injection of monocrotaline (60mg/kg). After two weeks, animals were treated for seven days with bucindolol (2mg/kg/day i.p.) or vehicle. At the end of the treatment, animals underwent echocardiographic assessment, catheterisation of the femoral artery and RV, and tissue collection for morphometric and histological evaluation. In the monocrotaline+bucindolol group, there was a decrease in mean pulmonary artery pressure (33%) and pulmonary congestion (21%), when compared to the monocrotaline. Bucindolol treatment also reduced RV pleomorphism, necrosis, fibrosis and infiltration of inflammatory cells. An improvement in RV systolic function was also observed in the monocrotaline+bucindolol group compared to the monocrotaline. In addition, bucindolol promoted a decrease in the cardiac sympathovagal balance (93%) by reducing sympathetic drive (70%) and increasing parasympathetic drive (142%). Bucindolol also reduced blood pressure variability (75%). Our results show that the beneficial effects from bucindolol treatment appeared to be a consequence of the reversal of monocrotaline-induced autonomic imbalance.

Peripheral endothelial function may predict the effectiveness of beta-blocker therapy in patients with idiopathic dilated cardiomyopathy

OBJECTIVES

Beta-blockers have improved the prognosis of patients with dilated cardiomyopathy as they improve left ventricular (LV) systolic function and structure, which are crucial for myocardial recovery. However, to date, no accurate methods can predict the effectiveness of β-blocker therapy. Our goal was to evaluate whether peripheral endothelial function could be a useful predictor for β-blocker responses and related LV reverse remodeling (LVRR) in patients with idiopathic dilated cardiomyopathy (IDC).

METHODS

Fifty-two IDC patients were recruited and underwent brachial artery flow-mediated dilation (FMD). Beta-blockers were titrated to doses tolerable for each patient. LV function and structure were measured by echocardiography. A positive response to β-blockers was defined as an increase of ≥10% in LV ejection fraction (LVEF). LVRR was defined as an increase of ≥10% in LVEF and a decrease of ≥15% in LV end-systolic volume (LVESV).

RESULTS

Baseline FMD was 8.4±3.0% in IDC patients and significantly lower than healthy controls. At three-month follow-up, 54% of patients had a positive β-blocker response and 40% achieved LVRR. Patients with a positive response to β-blockers or with LVRR had significantly higher baseline FMD values than those without. FMD was the most significant predictor of changes in LVEF and LVESV. The sensitivity and specificity of baseline FMD to predict β-blocker responses was 64.3% and 83.3%, respectively, and to predict LVRR was 61.9% and 80.6%, respectively. Beta-blockers themselves did not influence FMD values.

CONCLUSIONS

FMD could serve as an independent predictor for monitoring β-blocker therapy effectiveness in IDC patients.

Effect of tighter glycemic control on cardiac function, exercise capacity, and muscle strength in heart failure patients with type 2 diabetes: a randomized study

OBJECTIVES

In patients with type 2 diabetes (T2D) and heart failure (HF), the optimal glycemic target is uncertain, and evidence-based data are lacking. Therefore, we performed a randomized study on the effect of optimized glycemic control on left ventricular function, exercise capacity, muscle strength, and body composition.

DESIGN AND METHODS

40 patients with T2D and HF (left ventricular ejection fraction (LVEF) 35±12% and hemoglobin A1c (HbA1c) 8.4±0.7% (68±0.8 mmol/mol)) were randomized to either 4-month optimization (OPT group) or non-optimization (non-OPT group) of glycemic control. Patients underwent dobutamine stress echocardiography, cardiopulmonary exercise test, 6 min hall-walk test (6-MWT), muscle strength examination, and dual X-ray absorptiometry scanning at baseline and at follow-up.

RESULTS

39 patients completed the study. HbA1c decreased in the OPT versus the non-OPT group (8.4±0.8% (68±9 mmol/mol) to 7.6±0.7% (60±7 mmol/mol) vs 8.3±0.7% (67±10 mmol/mol) to 8.4±1.0% (68±11 mmol/mol); p<0.001). There was no difference between the groups with respect to changes in myocardial contractile reserve (LVEF (p=0.18)), oxygen consumption (p=0.55), exercise capacity (p=0.12), and 6-MWT (p=0.84). Muscle strength decreased in the non-OPT compared with the OPT group (37.2±8.1 to 34.8±8.3 kg vs 34.9±10.2 to 35.4±10.7 kg; p=0.01), in line with a non-significant decrease in lean (p=0.07) and fat (p=0.07) tissue mass in the non-OPT group. Hypoglycemia and fluid retention did not differ between groups.

CONCLUSIONS

4 months of optimization of glycemic control was associated with preserved muscle strength and lean body mass in patients with T2D and HF compared with lenient control, and had no deleterious effect on left ventricular contractile function and seemed to be safe.

TRIAL REGISTRATION NUMBER

NCT01213784; pre-results.

Left Bundle Branch Block Negatively Affects Coronary Flow Velocity Reserve and Myocardial Contractile Reserve in Nonischemic Dilated Cardiomyopathy

BACKGROUND

Coronary flow velocity reserve (CFVR) of the left anterior descending coronary artery (LAD) and myocardial contractile reserve are often impaired in nonischemic dilated cardiomyopathy (DCM). Whether they are affected by the presence of left bundle branch block (LBBB) remains unaddressed. The aim of the study was to investigate how LBBB influences CFVR of the LAD and myocardial contractile reserve in patients with DCM.

METHODS

One hundred eighty-one patients with DCM (116 men; mean age, 63 ± 12 years) underwent high-dose dipyridamole (0.84 mg/kg over 6 min) stress echocardiography with CFVR evaluation of the LAD by Doppler. All patients had ejection fractions < 40% (mean, 31 ± 8%) and angiographically normal or near normal coronary arteries. CFVR was defined as the ratio between hyperemic peak and basal peak diastolic coronary flow velocities. CFVR > 2.0 was considered normal. Inotropic reserve was defined as rest-stress variation in wall motion score index ≥ 0.20. This was a prospective analysis of an unselected sample consecutively enrolled and retrospectively selected.

RESULTS

The study group was separated on the basis of presence (n = 122) or absence (n = 59) of LBBB. Patients with LBBB were older (64 ± 11 vs 59 ± 12 years, P = .004) and had reduced resting ejection fractions (30 ± 9% vs 33 ± 7%, P = .02), CFVR of the LAD (1.96 ± 0.41 vs 2.23 ± 0.73, P = .001), and myocardial contractile reserve (variation in wall motion score index, -0.18 ± 0.17 vs -0.33 ± 0.28; P < .001). On multivariate logistic regression analysis, resting ejection fraction (hazard ratio [HR], 1.15; 95% CI, 1.03-1.29; P = .01), smoking habit (HR, 2.63; 95% CI, 1.23-5.62; P = .01), and LBBB (HR, 2.29; 95% CI, 1.05-5.04; P = .04) were independently associated with reduced CFVR, while restrictive transmitral pattern (HR, 2.56; 95% CI, 1.18-5.55; P = .02), end-diastolic volume (HR, 0.98; 95% CI, 0.67-0.99; P = .02), and LBBB (HR, 2.20; 95% CI, 1.11-4.34; P = .02) independently predicted reduced myocardial contractile reserve.

CONCLUSIONS

CFVR during vasodilator stress echocardiography is a suitable tool for assessing microvascular dysfunction in routine clinical practice. Patients with DCM and LBBB show more severe forms of microvascular dysfunction, which is related to worse left ventricular function and lack of contractile reserve. Therapeutic interventions to restore microvascular function may improve left ventricular function parameters in patients with DCM.

Dobutamine stress for evaluation of right ventricular reserve in pulmonary arterial hypertension

Right ventricular contractile response to pharmacological stress in pulmonary arterial hypertension (PAH) has not been characterised. We evaluated right ventricular contractile reserve in adults with PAH using dobutamine stress echocardiography.

16 PAH patients and 18 age-matched controls underwent low-dose dobutamine stress echocardiography. Contractile reserve was assessed by the change (Δ; peak stress minus rest value) in tricuspid annular plane systolic excursion (TAPSE) and tricuspid annular systolic velocity (S′). A subgroup of 13 PAH patients underwent treadmill cardiopulmonary exercise testing for peak oxygen uptake (V′O2peak).

At rest, TAPSE and S′ were reduced in the PAH group compared with controls (1.7±0.4 versus 2.4±0.2 cm and 9.7±2.6 versus 12.5±1.2 cm·s−1, respectively; p<0.05). Contractile reserve was markedly attenuated in PAH compared to controls (ΔTAPSE 0.1±0.2 versus 0.6±0.3 cm and ΔS′ 4.6±2.8 versus 11.2±3.6 cm·s−1; p<0.0001). In the sub-group of PAH patients with preserved right ventricular systolic function at rest, contractile reserve remained depressed compared to controls. V′O2peak was significantly correlated with ΔS′ (r=0.87, p=0.0003) and change in stroke volume (r=0.59, p=0.03).

Dobutamine stress can reveal sub-clinical reduction in right ventricular contractile reserve in patients with PAH. A correlation with exercise capacity suggests potential clinical value beyond resting measurements.

Response of functional mitral regurgitation during dobutamine infusion in relation to changes in left ventricular dyssynchrony and mitral valve geometry

PURPOSE

Functional mitral regurgitation (FMR) and myocardial dyssynchrony commonly occur in patients with dilated cardiomyopathy (DCM). The aim of this study was to elucidate changes in FMR in relation to those in left ventricular (LV) dyssynchrony as well as geometric parameters of the mitral valve (MV) in DCM patients during dobutamine infusion.

MATERIALS AND METHODS

Twenty-nine DCM patients (M:F=15:14; age: 62±15 yrs) with FMR underwent echocardiography at baseline and during peak dose (30 or 40 ug/min) of dobutamine infusion. Using 2D echocardiography, LV end-diastolic volume, end-systolic volume (LVESV), ejection fraction (EF), and effective regurgitant orifice area (ERO) were estimated. Dyssynchrony indices (DIs), defined as the standard deviation of time interval-to-peak myocardial systolic contraction of eight LV segments, were measured. Using the multi-planar reconstructive mode from commercially available 3D image analysis software, MV tenting area (MVTa) was measured. All geometrical measurements were corrected (c) by the height of each patient.

RESULTS

During dobutamine infusion, EF (28±8% vs. 39±11%, p=0.001) improved along with significant decrease in cLVESV (80.1±35.2 mm³/m vs. 60.4±31.1 mm³/m, p=0.001); cMVTa (1.28±0.48 cm²/m vs. 0.79±0.33 cm²/m, p=0.001) was significantly reduced; and DI (1.31±0.51 vs. 1.58±0.68, p=0.025) showed significant increase. Despite significant deterioration of LV dyssynchrony during dobutamine infusion, ERO (0.16±0.09 cm² vs. 0.09±0.08 cm², p=0.001) significantly improved. On multivariate analysis, ΔcMVTa and ΔEF were found to be the strongest independent determinants of ΔERO (R²=0.443, p=0.001).

CONCLUSION

Rather than LV dyssynchrony, MV geometry determined by LV geometry and systolic pressure, which represents the MV closing force, may be the primary determinant of MR severity.

Association between cardiopulmonary exercise and dobutamine stress testing in ambulatory patients with idiopathic dilated cardiomyopathy: a comparison with peak VO₂ and VE/VCO₂ slope

BACKGROUND

Both peak VO(2) and VE/VCO(2) slope are considered to be useful predictors of cardiovascular events. The left ventricular (LV) response to dobutamine stress testing (DST) also provides useful prognostic information. However, the relationship between these variables has not been fully investigated. Therefore, the aim of this study is to investigate the association between myocardial contractile reserve measured by DST and cardiopulmonary exercise testing (CPX) variables in patients with idiopathic dilated cardiomyopathy (IDCM).

METHODS

Thirty-eight patients were subjected to CPX as well as cardiac catheterization for measurement of LV pressure. The maximum first derivative of LV pressure (LV dP/dt(max)) was measured at baseline and during dobutamine infusion at incremental doses of 5, 10, and 15 μg kg(-1)min(-1). LV dP/dt(max) at baseline and the percentage increase in LV dP/dt(max) (ΔLV dP/dt(max)) induced by DST served as indices of LV contractility and myocardial contractile reserve, respectively.

RESULTS

Peak VO(2), and VE/VCO(2) slope were 18.6 mL kg(-1)min(-1) and 32.3, respectively. Peak VO(2) was not correlated with LV dP/dt(max) at baseline. However, peak VO(2) was significantly correlated with ΔLV dP/dt(max), and the correlation became more pronounced as the dose of dobutamine was increased. There was no correlation between VE/VCO(2) slope and ΔLV dP/dt(max). Multivariate regression analysis revealed that ΔLV dP/dt(max) was independently correlated with peak VO(2) (p=0.011).

CONCLUSIONS

Peak VO(2), but not VE/VCO(2) slope, may reflect myocardial contractile reserve in ambulatory patients with IDCM. This study population is small, and therefore large confirmatory studies are needed.

Usefulness of preoperative stroke volume as strong predictor of left ventricular remodeling and outcomes after aortic valve replacement in patients with severe pure aortic regurgitation

In most patients with aortic regurgitation (AR), aortic valve replacement (AVR) results in favorable left ventricular (LV) remodeling and normalization of the LV ejection fraction (EF). However, some patients with severe AR will not have favorable remodeling and their LVEF will not normalize. The goal of the present study was to determine whether remodeling and clinical outcomes after AVR could be predicted from simple preoperative echocardiographic analysis. A total of 56 consecutive patients with chronic severe pure AR who underwent AVR had preoperative (5 ± 2 days), early postoperative (5 ± 2 days), and late postoperative (328 ± 88 days) echocardiographic data retrospectively analyzed. The LV diameter, The LVEF and stroke volume (SV) were measured. The reduction in LV end-diastolic dimension decreased by 14% (from 65 ± 6 mm to 56 ± 8 mm, p <0.001) early after AVR, with an additional reduction of only 6% late after AVR. More than 2/3 of the overall reduction in end-diastolic dimension was observed the week after AVR. Forty-six patients (82%) had positive early LV remodeling, defined as a 10% reduction in the LV end-diastolic diameter 1 week after AVR. All patients with early LV remodeling had a preoperative SV of ≥97 ml, which was the best predictor of late postoperative LVEF of ≥45% (sensitivity 98% and specificity 100%). Patients with a preoperative SV of ≥97 ml had a markedly greater event-free survival rate (92% vs 13%, p <0.001) at 3 years. In conclusion, in patients undergoing AVR for chronic severe pure AR, preoperative SV is the best predictor of LV remodeling and outcomes.

Bucindolol: a pharmacogenomic perspective on its use in chronic heart failure

Bucindolol is a non-selective β-adrenergic receptor blocker with α-1 blocker properties and mild intrinsic sympatholytic activity. The Beta-Blocker Evaluation of Survival Trial (BEST), which is the largest clinical trial of bucindolol in patients with heart failure, was terminated prematurely and failed to show an overall mortality benefit. However, benefits on cardiac mortality and re-hospitalization rates were observed in the BEST trial. Bucindolol has not shown benefits in African Americans, those with significantly low ejection fraction and those in NYHA class IV heart failure. These observations could be due to the exaggerated sympatholytic response to bucindolol in these sub-groups that may be mediated by genetic polymorphisms or changes in gene regulation due to advanced heart failure. This paper provides a timely clinical update on the use of bucindolol in chronic heart failure.

Dobutamine-Induced Improvement in Inferior Myocardial Contractile Function Predicts Reduction in Functional Mitral Regurgitation

Background—

Left ventricular (LV) remodeling can increase tethering force to mitral valve and functional mitral regurgitation (FMR). Because the relationship between FMR and regional myocardial function has not been quantitatively evaluated, we conducted a quantitative investigation of this association.

Methods and Results—

The effective regurgitant orifice (ERO) of FMR in 51 patients with depressed LV ejection fraction (32±9%) secondary to ischemic or nonischemic cardiomyopathy was compared with mitral deformation (valve and annulus), global LV remodeling (volume indices, function, and sphericity), and regional myocardial contractile function, as assessed by longitudinal peak systolic strain rate (Ssr) in LV anterior, anteroseptal, inferoseptal, inferior, inferolateral, and anterolateral segments at rest. Low-dose dobutamine (10 μg/kg per minute)-induced changes in ERO were compared with changes in the variables. Multivariable analysis identified the predictors of ERO at rest as mitral valvular tenting (β=0.062; P <0.001), Ssr in the inferior segment (inferior Ssr) (β=−0.178; P <0.001), and LV sphericity (β=0.414; P =0.001) and the predictors of valvular tenting at rest as inferior Ssr (β=−1.680; P <0.001), LV end-systolic volume index (β=0.022; P =0.001), and LV sphericity (β=3.886; P =0.012). Furthermore, dobutamine-induced reduction in ERO was predicted by reduction in valvular tenting (β=0.087; P <0.001) and increase in inferior Ssr (β=−0.082; P <0.001), and dobutamine-induced reduction in valvular tenting was predicted by increase in inferior Ssr (β=−0.860; P <0.001).

Conclusions—

Inferior regional myocardial dysfunction was quantitatively associated with mitral valvular tenting and FMR. Moreover, improvement with dobutamine of inferior myocardial contractile function attenuated valvular tenting and FMR. Inferior myocardial contractile function can affect the configuration of the mitral apparatus and predict FMR severity.

Role of beta-adrenergic receptor gene polymorphisms in the long-term effects of beta-blockade with carvedilol in patients with chronic heart failure

BACKGROUND

Beta-blockers are mainstay of current treatment of heart failure (HF). Beta-adrenergic receptors (AR) single nucleotide gene polymorphisms (SNPs) may influence the sensitivity and density of beta-AR. We assessed the relation between three common beta-AR SNPs and the response to carvedilol administration.

METHODS AND RESULTS

We studied 183 consecutive patients with chronic HF due to ischemic or nonischemic cardiomyopathy, a LV ejection fraction (LVEF) < or = 0.35, not previously treated with beta-blockers. Each patient underwent gated-SPECT radionuclide ventriculography, cardiopulmonary exercise testing and invasive hemodynamic monitoring at baseline and after 12 months of carvedilol administration at maintenance dosages. The beta1-AR gene Arg389Gly and the beta2-AR gene Arg16Gly SNPs were not related to the response to carvedilol administration. Homozygotes for the Glu27Glu allele showed a greater increase in the LVEF, compared to the other patients (+13.0 +/- 12.2% versus +7.1 +/- 8.1% in the Gln27Gln homozygotes, and 8.3 +/- 11.4% units in the Gln27Glu heterozygotes; p = 0.022 by ANOVA). Glu27Glu homozygotes also showed a greater decline in the pulmonary wedge pressure both at rest and at peak exercise. Gln27Glu SNP was selected amongst the determinants of the LVEF response to carvedilol at multivariable analysis, in addition to the cause of cardiomyopathy, baseline systolic blood pressure and the dose of carvedilol administered.

CONCLUSION

Beta1-AR Arg389Gly and beta2-AR Arg16Gly SNPs are not related to the response to carvedilol therapy. In contrast, the Gln27Glu SNP is a determinant of the LVEF response to this agent in patients with chronic HF.

Myocardial perfusion reserve and contractile pattern after beta-blocker therapy in patients with idiopathic dilated cardiomyopathy

BACKGROUND

In Idiopathic Dilated Cardiomyopathy (IDC) an imbalance between myocardial oxygen consumption and supply has been postulated. The ensuing subclinical myocardial ischemia may contribute to progressive deterioration of LV function. beta-blocker is the therapy of choice in these patients. However, not all patients respond to the same extent. The aim of this study was to elucidate whether differences between responders and non-responders can be identified with respect to regional myocardial perfusion reserve (MPR) and contractile performance.

METHODS

Patients with newly diagnosed IDC underwent Positron Emission Tomography (PET) scanning using both (13)N-ammonia as a perfusion tracer (baseline and dipyridamole stress), and (18)F-fluoro-deoxyglucose as a metabolism tracer, and a dobutamine stress MRI. MRI and PET were repeated 6 months after maximal beta-blocker therapy. MPR (assessed by PET) as well as wall motion score (WMS, assessed by MRI) were evaluated in a 17 segment-model. Functional response to beta-blocker therapy was assigned as a stable or improved LVEF or diminished LVEF.

RESULTS

Sixteen patients were included (age 47.9 +/- 11.5 years; 12 males, LVEF 28.6 +/- 8.4%). Seven patients showed improved LVEF (9.7 +/- 3.1%), and nine patients did not show improved LVEF (-3.4 +/- 3.9%). MPR improved significantly in responders (1.56 +/- .23 to 1.93 +/- .49, P = .049), and MPR decreased in non-responders; however, not significantly (1.98 +/- .70 to 1.61 +/- .28, P = .064), but was significantly different between both groups (P = .017) after beta-blocker therapy. A significant correlation was found between change in perfusion reserve and change in LVEF: a decrease in perfusion reserve was associated with a decrease in LVEF and vice versa. Summed rest score of wall motion in responders improved from 26 to 21 (P = .022) whereas in non-responders no change was observed from 26 to 25) (P = ns). Summed stress score of wall motion in responders improved from 23 to 21 (P = .027) whereas in non-responders no change was observed from 27 to 26) (P = ns).

CONCLUSION

In IDC patients, global as well as regional improvement after initiation of beta-blocker treatment is accompanied by an improvement in regional perfusion parameters. On the other hand in IDC patients with further left ventricular function deterioration after initiation of beta-blocker therapy this is accompanied by a decrease in perfusion reserve.

Relation between regional and global systolic function in patients with ischemic cardiomyopathy after beta-blocker therapy or revascularization

BACKGROUND

To assess the relationship between improved regional and global myocardial function in patients with ischemic cardiomyopathy in response to beta-blocker therapy or revascularization.

MATERIALS AND METHODS

Cardiovascular magnetic resonance (CMR) was performed in 32 patients with ischemic cardiomyopathy before and 8 +/- 2 months after therapy. Patients were assigned clinically to beta-blocker therapy (n = 20) or revascularization (n = 12). CMR at baseline was performed to assess regional and global LV function at rest and under low-dose dobutamine. Wall thickening was analyzed in dysfunctional, adjacent, and remote segments. Follow-up CMR included rest function evaluation.

RESULTS

Augmentation of wall thickening during dobutamine at baseline was similar in dysfunctional, adjacent and remote segments in both patient groups. Therefore, baseline characteristics were similar for both patient groups. In both patient groups resting LV ejection fraction and end-systolic volume improved significantly (p < 0.05) at follow-up. Stepwise multivariate analysis revealed that improvement in global LV ejection fraction in the beta-blocker treated patients was significantly related to improved function of remote myocardium (p < 0.05), whereas in the revascularized patients improved function in dysfunctional and adjacent segments was more pronounced (p < 0.05).

CONCLUSION

In patients with chronic ischemic LV dysfunction, beta-Blocker therapy or revascularization resulted in a similar improvement of global systolic LV function. However, after beta-blocker therapy, improved global systolic function was mainly related to improved contraction of remote myocardium, whereas after revascularization the dysfunctional and adjacent regions contributed predominantly to the improved global systolic function.

Usefulness and limitation of dobutamine stress echocardiography to predict acute response to cardiac resynchronization therapy

BACKGROUND

It has been hypothesized that a long-term response to cardiac resynchronization therapy (CRT) could correlate with myocardial viability in patients with left ventricular (LV) dysfunction. Contractile reserve and viability in the region of the pacing lead have not been investigated in regard to acute response after CRT.

METHODS

Fifty-one consecutive patients with advanced heart failure, LV ejection fraction <or= 35%, QRS duration > 120 ms, and intraventricular asynchronism >or= 50 ms were prospectively included. The week before CRT implantation, the presence of viability was evaluated using dobutamine stress echocardiography. Acute responders were defined as a >or=15% increase in LV stroke volume.

RESULTS

The average of viable segments was 5.8 +/- 1.9 in responders and 3.9 +/- 3 in nonresponders (P = 0.03). Viability in the region of the pacing lead had an excellent sensitivity (96%), but a low specificity (56%) to predict acute response to CRT. Mitral regurgitation (MR) was reduced in 21 patients (84%) with acute response. The presence of MR was a poor predictor of response (sensibility 93% and specificity 17%). However, combining the presence of MR and viability in the region of the pacing lead yields a sensibility (89%) and a specificity (70%) to predict acute response to CRT.

CONCLUSION

Myocardial viability is an important factor influencing acute hemodynamic response to CRT. In acute responders, significant MR reduction is frequent. The combined presence of MR and viability in the region of the pacing lead predicts acute response to CRT with the best accuracy.

Beta-blocker use for the stages of heart failure

The 2005 American Heart Association/American College of Cardiology heart failure (HF) guidelines contributed to a renewed focus on "at-risk" patients and emphasized HF as a progressive disease. Patient categorization by stages focused attention on customization of therapy to achieve optimal, evidence-based treatments across the HF continuum. Therapy for risk factors that predispose patients to left ventricular dysfunction or other symptoms may help reduce HF development. beta-Blockers are valuable for treatment of HF; however, the class is heterogeneous, and proper beta-blocker selection for each HF stage is important. beta-Blockers have been used routinely to treat patients with stage A HF with hypertension. Recent controversy regarding the detrimental effects that some beta-blockers have on metabolic parameters has raised inappropriate concerns about the use of any beta-blocker for diabetes. beta-Blockade is standard therapy for the patient with stage B HF who has had a myocardial infarction, but few data are available concerning use in asymptomatic patients with left ventricular dysfunction. Additionally, beta-blockers are part of the core therapy for stage C HF and selected patients with stage D HF. This review examines the role and use of beta-blockers in each HF stage through an evidence-based approach to provide better understanding of their importance in this progressive disease. PubMed searches (1980-2008) identified large clinical trials that evaluated cardiovascular events and outcomes in any HF stage or hypertension. Search terms were heart failure, hypertension, beta-blocker, ACEI, ARB, and calcium channel blocker AND blood pressure coronary artery disease, diabetes, efficacy, left ventricular dysfunction, metabolism, mortality, myocardial infarction, or stroke.

Myocardial beta-adrenergic receptor density assessed by 11C-CGP12177 PET predicts improvement of cardiac function after carvedilol treatment in patients with idiopathic dilated cardiomyopathy

We evaluated whether myocardial beta-adrenergic receptor (beta-AR) density, as determined by 11C-CGP12177 PET, could predict improvement of cardiac function by beta-blocker carvedilol treatment in patients with idiopathic dilated cardiomyopathy (IDC).

METHODS

Ten patients with IDC (left ventricular ejection fraction [LVEF]<45%) were studied. Myocardial beta-AR density was estimated using 11C-CGP12177 PET before treatment with carvedilol. Changes of LVEF in response to dobutamine infusion (DeltaLVEF-dobutamine) were also measured by echocardiography. Changes of LVEF (DeltaLVEF-carvedilol) were evaluated after 20 mo of carvedilol treatment.

RESULTS

Baseline myocardial beta-AR density significantly correlated with DeltaLVEF-carvedilol (r=-0.88, P<0.001). In contrast, DeltaLVEF-dobutamine did not correlate with DeltaLVEF-carvedilol (P=0.65). Myocardial beta-AR density was the significant multivariate independent predictor of DeltaLVEF-carvedilol (beta=-0.88, P<0.001) among univariate predictors, including functional class (r=0.76, P<0.05), plasma norepinephrine (r=0.85, P<0.01), LVEF (r=-0.64, P<0.05), and age as confounding factors. Furthermore, myocardial beta-AR density was significantly correlated with plasma norepinephrine (r=-0.79, P<0.01) and LVEF (r=0.70, P<0.05).

CONCLUSION

Myocardial beta-AR density is more tightly related to improvement of LVEF-carvedilol than is cardiac contractile reserve in patients with IDC. Patients with decreased myocardial beta-AR have higher resting adrenergic drive, as reflected by plasma norepinephrine, and may receive greater benefit from being treated by antiadrenergic drugs.

The function of left ventricular basal segments is most important for long-term recovery

Adrenergic beta-blockade is the most potent pharmacological therapy for the improvement of global left ventricular (LV) function in heart failure. A substantial portion of patients responds poorly to beta-blockers, but there is scarce information about LV regional function and recovery. We intended to evaluate the effects of beta-blockade on LV regional function and recovery, contractile reserve (CR) and response to long-term treatment.

METHODS

Twenty-two patients with heart failure were investigated at rest and during dobutamine stress echocardiography (DSE), before and after 6 months of metoprolol treatment. LV function was evaluated by global ejection fraction (EF), and by regional function in basal, mid and apical segments.

RESULTS

Recovery of LV global function (increase in EF >5%) after metoprolol treatment was significantly and best correlated to CR in basal segments of the ventricle (r=0.79, p<0.001), in comparison with function of mid and apical segments. The correlation between global recovery and global CR was r=0.55, p=0.007. In a multivariate logistic regression, including global and regional CR, age, gender, etiology of heart failure, ACE-inhibitor treatment, heart rate, and baseline EF, only basal CR was independently associated with recovery, OR 1.07 [95% CI, 1.01-1.21], p=0.019.

CONCLUSION

The strongest association for prediction of LV recovery after metoprolol treatment was found regarding function of basal segments of the ventricle. Patients that responded favourably to beta-blockade had a significantly better CR, and treatment effect, in these segments. This gives further evidence for the importance of myocardial function in basal segments to the contribution of recovery and LV global function.

The effects of beta-blockers in patients with stable chronic heart failure. Predictors of left ventricular ejection fraction improvement and impact on prognosis

BACKGROUND

Previous studies, with limited number of patients, have tried to determine the predictors of left ventricular ejection fraction (LVEF) improvement after beta-blockade. No study has demonstrated that LVEF improvement was an independent predictor of cardiac survival.

METHODS

The aims of the study were to determine in a large group of patients with stable chronic heart failure associated with reduced LVEF the predictors of LVEF improvement (difference in LVEF [deltaLVEF], ie, the value after beta-blockade minus the value before beta-blockade) after beta-blockade and to analyze prognostic impact of deltaLVEF. Three hundred fourteen consecutive patients underwent an echocardiogram, a radionuclide angiogram, and a maximum cardiopulmonary exercise test before and 3 months after maximal tolerated doses of beta-blockers have been reached.

RESULTS

After beta-blockade, LVEF improved from 30% +/- 11% to 40% +/- 13%. In the whole population, independent predictors of deltaLVEF were nonischemic etiology, baseline LVEF (negative correlation), and baseline heart rate (positive correlation). In ischemic patients, independent predictors of deltaLVEF were absence of history of myocardial infarction, baseline heart rate, and baseline LVEF; whereas in nonischemic patients, independent predictors were baseline LVEF and baseline QRS width (negative correlation). After 1082 days of follow-up, there were 53 cardiovascular deaths and 2 urgent transplantations. Left ventricular ejection fraction improvement (defined as an absolute increase in LVEF > 5%) was an independent predictor of cardiac survival. Patients who had an LVEF < or = 45% after beta-blockade with a deltaLVEF < or = 5% represented a high-risk subgroup.

CONCLUSIONS

In patients with chronic heart failure, predictors of LVEF improvement after beta-blockade were different according to etiology. Left ventricular ejection fraction improvement was an independent predictor of cardiac survival.

Cardiac Reserve in the Transplanted Heart: Effect of a Graft Polymorphism in the β1-adrenoceptor

BACKGROUND

Polymorphism of the beta1-adrenoceptor (beta1-AR) affects outcome and beta-blocker efficacy in patients with heart failure. We studied the influence of the beta1-AR Ser49Gly polymorphism on cardiac reserve in transplanted hearts.

METHODS

Beta1-AR polymorphism was determined by allelic discrimination analysis. Patients were divided into two groups: either homozygous for Ser49 (n = 15) or with Gly49 in one or both alleles (Gly49; n = 5). Patients underwent a maximal bicycle exercise test and echocardiographic evaluation at rest and during low-dose dobutamine stress.

RESULTS

Patients with Gly49 grafts had better physical endurance (144 +/- 26 vs 112 +/- 31 W, p = 0.03), a trend toward better chronotropic reserve (deltaHR 64 +/- 13 vs 47 +/- 16 bpm, p = 0.056) during exercise, and lower resting heart rate (82 +/- 7 vs 90 +/- 7 bpm, p = 0.04) than those homozygous for Ser49. There were no significant differences in left ventricular ejection fraction (LVEF), with the exception of a decrease in cardiac reserve in patients with the Gly49 variants at the lowest dose of dobutamine (deltaLVEF -4.4 +/- 1.5 vs 2.2 +/- 5.8%, p = 0.04). Doppler myocardial tissue velocities of early relaxation were increased in patients with the Gly49 variants compared with patients homozygous for Ser49, both at rest (14.5 +/- 3.2 vs 10.4 +/- 2.0 cm/s, p = 0.03) and during the lowest dose of dobutamine (15.0 +/- 3.7 vs 10.9 +/- 2.5 cm/s, p = 0.04).

CONCLUSIONS

Heart transplant patients with the beta1-AR Gly49 variants had a lower heart rate, and better stress endurance and diastolic function compared with patients homozygous for Ser49. They also showed a trend toward better chronotropic reserve. These results provide a possible explanation for differences in cardiac reserve among patients with heart transplants.

Pronounced improvement in systolic and diastolic ventricular long axis function after treatment with metoprolol

BACKGROUND

Although it is well known that left ventricular (LV) function improves after treatment with beta-blockers in heart failure, little attention has been paid to the effects on LV long axis (LAX) function.

AIMS

To evaluate LV LAX function after treatment with metoprolol, and to assess whether LV LAX contractile reserve could predict future long-term improvement.

METHODS

Twenty-four heart failure patients were randomised to metoprolol or placebo for 6 months, followed by 6 months of open treatment with metoprolol. Rest and dobutamine stress echocardiography (DSE) was performed before and after each treatment period.

RESULTS

After treatment with metoprolol, LV LAX function improved significantly, systolic velocity from 29+/-8 to 32+/-15 mm/s, p<0.01 (metoprolol) vs. 28+/-7 to 28+/-11 mm/s, ns (placebo); atrioventricular plane fractional shortening (AVP-FS) from 5.4+/-2.1 to 7.4+/-2.7%, p<0.001 (metoprolol) vs. 5.9+/-2.1 to 5.8+/-2.9%, ns (placebo). The improvement in function was maintained during DSE. LV LAX contractile reserve could not predict treatment response; the treatment effect on LV LAX function was significantly greater than the contractile reserve at baseline. The relative improvement in LV LAX function after metoprolol was 38%, compared with a 20% improvement in LV ejection fraction (EF).

CONCLUSION

A significant improvement in LV LAX function was observed after treatment with metoprolol. AVP-FS and systolic velocities increased significantly, and to a greater extent than LVEF.

Depressed Myocardial Contractile Reserve in Patients With Obstructive Sleep Apnea Assessed by Tissue Doppler Imaging With Dobutamine Stress Echocardiography

BACKGROUND

Hypoxia has been suggested to affect myocardial contractile function in patients with obstructive sleep apnea (OSA). We sought to determine whether myocardial contractile reserve (MCR), as evaluated by echocardiographic tissue Doppler imaging with dobutamine stress (TDDS), might be depressed in OSA patients.

METHODS

Thirty patients with suspected OSA (25 men and 5 women; mean age, 51 +/- 11 years [+/- SD]) underwent overnight polysomnography and TDDS. Peak myocardial systolic velocity (Sm) and peak myocardial early diastolic velocity (Em) in the 12 myocardial segments of the left ventricular (LV) walls were averaged, and the mean Sm and Em during TDDS were compared between patients with apnea-hypopnea index (AHI) <15/h (group 1, n = 13) and those with AHI >/= 15/h (group 2, n = 17). MCR was calculated as the difference between the resting and peak Sm during TDDS.

RESULTS

In both groups, Sm increased dose dependently during TDDS. However, the relative increase in Sm was significantly lower in group 2, resulting in a lower value of MCR (5.5 +/- 1.2 cm/s vs 7.4 +/- 1.3 cm/s, p < 0.001). The Em was lower in group 2 compared with group 1 throughout TDDS. MCR was correlated significantly with AHI (r = - 0.67, p < 0.0001), resting Em (r = 0.53, p < 0.005), and body mass index (r = - 0.46, p < 0.05) independent of the LV mass index.

CONCLUSIONS

OSA can affect MCR, implying an etiologic contribution from repetitive hypoxic events. TDDS could identify subtle abnormalities of OSA-related cardiac involvement.

Comparison of two- and three-dimensional echocardiography with sequential magnetic resonance imaging for evaluating left ventricular volume and ejection fraction over time in patients with healed myocardial infarction

Echocardiographic follow-up of left ventricular (LV) volumes is difficult because of the test-retest variation of 2-dimensional echocardiography (2DE). We investigated whether the accuracy and reproducibility of real-time 3-dimensional echocardiography (RT3DE) would make this modality more feasible for serial follow-up of LV measurements. We performed 2DE and RT3DE and cardiac magnetic resonance imaging (MRI) in 50 patients with previous infarction and varying degrees of LV function (44 men; 61 +/- 11 years of age) at baseline and after 1-year follow-up. Images were obtained during breath-hold and measurements of LV volumes and ejection fraction were made offline. Over follow-up, end-diastolic volume decreased from 192 +/- 53 to 187 +/- 60 ml (p <0.01), end-systolic volume decreased from 104 +/- 51 to 95 +/- 53 ml (p <0.01), and ejection fraction increased from 48 +/- 12% to 51 +/- 12% (p <0.01). MRI showed that LV mass shrank from 183 +/- 39 to 182 +/- 37 g (p <0.01). The correlation between change in RT3DE and change in MRI was greater than the correlations of 2DE with MRI for measurement of end-diastolic volume (r = 0.47 vs 0.02, p <0.01), end-systolic volume (r = 0.44 vs 0.17, p <0.01), and ejection fraction (r = 0.58 vs -0.03, p <0.01). The change in end-diastolic volume between baseline and follow-up with RT3DE (-4 +/- 20, p <0.01) was similar to that with MRI but was unrecognized by 2DE (4 +/- 19, p = 0.09). There was good test-retest and inter- and intraobserver correlation within RT3DE for volumes, ejection fraction, and mass. In conclusion, if sequential measurement of LV volumes is used to guide management decisions, 3DE appears preferable to 2DE.