Prognostic significance of the dobutamine echocardiography test in idiopathic dilated cardiomyopathy

Anesthetic Management of Patients with Dilated Cardiomyopathy Undergoing Noncardiac Surgery

Dilated cardiomyopathy (DCM), a primary myocardial disease, is characterized by dilation of the left or both ventricles and systolic dysfunction with or without congestive heart failure. DCM per se is a well-recognized risk factor for sudden cardiac death and poor surgical outcomes following noncardiac surgery. Surgical trauma/stress represents unique challenges for DCM patient management. Unfortunately, there is a big knowledge gap in managing DCM patients undergoing non-cardiac surgery. Therefore, the aim of our review is to provide basic facts and current advances in DCM, as well as a practical guideline to perioperative care providers, for the management of surgical patients with DCM, who are quite rare compared with the general surgical population. This review summarizes recent advances in the medical management of DCM as well as perioperative assessment and management strategies for DCM patients undergoing noncardiac surgery. Optimal surgical outcomes depend on multiple-disciplinary care to minimize perioperative cardiovascular disturbances.

Suppression of lusitropy as a disease mechanism in cardiomyopathies

In cardiac muscle the action of adrenaline on β1 receptors of heart muscle cells is essential to adjust cardiac output to the body's needs. Adrenergic activation leads to enhanced contractility (inotropy), faster heart rate (chronotropy) and faster relaxation (lusitropy), mainly through activation of protein kinase A (PKA). Efficient enhancement of heart output under stress requires all of these responses to work together. Lusitropy is essential for shortening the heartbeat when heart rate increases. It therefore follows that, if the lusitropic response is not present, heart function under stress will be compromised. Current literature suggests that lusitropy is primarily achieved due to PKA phosphorylation of troponin I (TnI) and phospholamban (PLB). It has been well documented that PKA-induced phosphorylation of TnI releases Ca2+ from troponin C faster and increases the rate of cardiac muscle relaxation, while phosphorylation of PLB increases SERCA activity, speeding up Ca2+ removal from the cytoplasm. In this review we consider the current scientific evidences for the connection between suppression of lusitropy and cardiac dysfunction in the context of mutations in phospholamban and thin filament proteins that are associated with cardiomyopathies. We will discuss what advances have been made into understanding the physiological mechanism of lusitropy due to TnI and PLB phosphorylation and its suppression by mutations and we will evaluate the evidence whether lack of lusitropy is sufficient to cause cardiomyopathy, and under what circumstances, and consider the range of pathologies associated with loss of lusitropy. Finally, we will discuss whether suppressed lusitropy due to mutations in thin filament proteins can be therapeutically restored.

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.

Pulse pressure and prognosis in patients with heart failure with reduced ejection fraction

BACKGROUND

A high pulse pressure (PP) is associated with adverse cardiovascular (CV) outcomes; however, this relationship may be reversed in patients with heart failure with reduced ejection fraction (HFREF).

METHODS

Patients from the WARCEF trial with left ventricular ejection fraction ≤35% were included. PP was divided into tertiles: ≤42, 42-54 and >54 mm Hg. Age and ejection fraction adjusted Kaplan-Meier curves were generated to evaluate the relationship between PP and outcomes [mortality, CV mortality, stroke and HF hospitalizations (HFH)]. Cox proportional hazards models were created incorporating PP as a continuous variable. The interaction of PP with New York Heart Association (NYHA) functional class was examined. Linear and restricted cubic splines were used to study nonlinear association between PP and outcomes.

RESULTS

We included 2,299 patients with a mean(±SD) follow-up of 3.5 ± 1.8 years. The lowest tertile of PP (≤42 mm Hg) was associated with significantly higher CV mortality and HFH. Cox proportional hazards models showed a reduction in CV death and HFH with higher PP, with adjusted hazard ratios (HR) of 0.91 (P = 0.02) and 0.93 (P = 0.04) per 10 mm Hg increase in PP. This relationship was more pronounced in subjects with NYHA functional class III-IV. Spline analysis showed that the association between PP and CV mortality and HFH was only seen at PP values lower than 40 mm Hg.

CONCLUSIONS

In patients with advanced HFREF, a low PP (<40 mm Hg) portends a worse prognosis, whereas a high PP (>50 mm Hg) predicts a relatively favourable prognosis.

Contractile reserve as a predictor of prognosis in patients with non-ischaemic systolic heart failure and dilated cardiomyopathy: a systematic review and meta-analysis

Objective

Patients with non-ischaemic systolic heart failure (HF) and idiopathic dilated cardiomyopathy (DCM) are a heterogenous group with varied morbidity and mortality. Prognostication in this group is challenging. We performed a systematic review and meta-analysis to examine the significance of the presence of contractile reserve as assessed via stress imaging on mortality and hospitalisation.

Methods

A search for studies that non-invasively assessed contractile reserve in patients with DCM or non-ischaemic HF with reduced ejection fraction, stress imaging with follow-up data comparing outcomes. A range of imaging modalities and stressors were included. We examined primary endpoints of mortality and secondary endpoints of combined cardiovascular events including HF progression or hospitalisation. Our analysis compared endpoints in patients with contractile reserve and those without it.

Results

Nine prospective cohort studies were identified describing a total of 787 patients. These studies are methodologically but not statistically heterogenous (I² = 31%). Using a random effect model, the presence of contractile reserve was associated with a significantly lower risk of mortality and cardiovascular events odds ratios of 0.20 (CI 0.11, 0.39) (P < 0.00001) and 0.13 (CI 0.04, 0.40) (P = 0.0004), respectively.

Conclusion

Regardless of stressor and imaging modality and despite the significant methodological heterogeneity within the current data (imaging techniques and parameters), patients with non-ischaemic cardiomyopathy and reduced EF who demonstrate contractile reserve have a lower mortality, and lower events/hospitalisations. The presence of contractile reserve therefore offers a potential positive prognostic indicator when managing these patients.

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.

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.

Endomyocardial radial strain rate imaging during dobutamine stress echocardiography for the evaluation of contractile reserve in patients with dilated cardiomyopathy

PURPOSE

Myocardial contractile reserve is associated with clinical prognosis in patients with dilated cardiomyopathy (DCM). We assessed myocardial contractile reserve using tissue Doppler strain rate imaging with dobutamine stress echocardiography in DCM patients.

METHODS

Simultaneous echocardiography and left ventricular (LV) catheterization during dobutamine stress were performed in 20 patients with DCM, and echocardiography was performed in 31 control subjects. Dobutamine was infused at a starting dose of 5 μg/kg/min for 5 minutes and then at 10 μg/kg/min. Peak endomyocardial radial strain (ɛ) and systolic strain rate (SR_sys ) measured with echocardiography and the maximum first derivative of LV pressure (LV dP/dt_max ) derived from catheterization were used as indices of contractility. Their percentage change from baseline to the dose of 10 μg/kg/min was calculated.

RESULTS

The ɛ and SR_sys were significantly smaller in DCM patients than in controls. The LV dP/dt_max , ɛ, and SR_sys were significantly higher at the dose of 10 μg/kg/min than at baseline. The percentage change in SR_sys was significantly correlated with the percentage change in LV dP/dt_max .

CONCLUSIONS

Strain rate imaging during dobutamine stress in DCM might prove noninvasively informative for the evaluation of myocardial contractile reserve and provide insight into LV systolic dysfunction. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 44:555-560, 2016.

Severe Bioprosthetic Mitral Valve Stenosis and Heart Failure in a Young Woman with Systemic Lupus Erythematosus

A 23-year-old African American woman with a past medical history of systemic lupus erythematous (SLE), secondary hypertension, and end stage renal disease (ESRD) on hemodialysis for eight years was stable until she developed symptomatic severe mitral regurgitation with preserved ejection fraction. She underwent a bioprosthetic mitral valve replacement (MVR) at outside hospital. However, within a year of her surgery, she presented to our hospital with NYHA class IV symptoms. She was treated for heart failure but in view of her persistent symptoms and low EF was considered for heart and kidney transplant. This was a challenge in view of her history of lupus. We presumed that her stenosis of bioprosthetic valve was secondary to lupus and renal disease. We hypothesized that her low ejection fraction was secondary to mitral stenosis and potentially reversible. We performed a dobutamine stress echocardiogram, which revealed an improved ejection fraction to more than 50% and confirmed preserved inotropic contractile reserve of her myocardium. Based on this finding, she underwent a metallic mitral valve and tricuspid valve replacement. Following surgery, her symptoms completely resolved. This case highlights the pathophysiology of lupus causing stenosis of prosthetic valves and low ejection cardiomyopathy.

Prognostic value of cardiac power output to left ventricular mass in patients with left ventricular dysfunction and dobutamine stress echo negative by wall motion criteria

AIMS

Cardiac power output to left ventricular mass (power/mass) is an index of myocardial efficiency reflecting the rate at which cardiac work is delivered with respect to the potential energy stored in the left ventricular mass. In the present study, we sought to investigate the capability of power/mass assessed at peak of dobutamine stress echocardiography to predict mortality in patients with ischaemic cardiomyopathy and no inducible ischaemia.

METHODS AND RESULTS

One-hundred eleven patients (95 males; age 68 ± 10 years) with 35 ± 7% mean left ventricular ejection fraction and a dobutamine stress echocardiography (up to 40 µg/kg/min) negative by wall motion criteria formed the study population. Power/mass at peak stress was obtained as the product of a constant (K = 2.22 × 10^-1) with cardiac output and the mean arterial pressure divided by left ventricular mass to convert the units to W/100 g. Patients were followed up for a median of 29 months (inter-quartile range 16-72 months). All-cause mortality was the only accepted clinical end point. Mean peak-stress power/mass was 0.70 ± 0.31 W/100 g. During follow-up, 29 deaths (26%) were registered. With a receiver operating characteristic analysis, a peak-stress power/mass ≤0.50 W/100 g [area under curve 0.72 (95% CI 0.63; 0.80), sensitivity 59%, specificity 80%] was the best value for predicting mortality. Univariate prognostic indicators were age, male sex, peak-stress ejection fraction, peak-stress stroke volume, peak-stress cardiac output, peak-stress cardiac power output ≤1.48 W, and peak-stress power/mass ≤0.50 W/100 g. At multivariate analysis, age (HR 1.08, 95% CI 1.04; 1.14; P = 0.004) and peak-stress power/mass ≤0.50 W/100 g (HR 4.05, 95% CI 1.36; 12.00; P = 0.01) provided independent prognostic information. Three-year mortality was 14% in patients with peak-stress power/mass >0.50 W/100 g and 47% in those with peak-stress power/mass ≤0.50 W/100 g (log-rank 20.4; P < 0.0001).

CONCLUSION

Power/mass assessed at peak of dobutamine stress echocardiography allows effective prognostication in patients with ischaemic cardiomyopathy and test result negative by wall motion criteria. In particular, a peak-stress power/mass ≤50 W/100 g is a strong and multivariable predictor of mortality.

Significant prognostic impact of improvement in ventriculo-arterial coupling induced by dobutamine stress on cardiovascular outcome for patients with dilated cardiomyopathy

AIMS

The purpose of this study was to investigate the prognostic impact of the changes in ventriculo-arterial (VA) coupling during dobutamine stress on the cardiovascular events for patients with dilated cardiomyopathy (DCM).

METHODS AND RESULTS

For this study, 89 DCM patients with ejection fractions of 32 ± 10% and 30 normal controls were recruited. Ees was estimated with the non-invasive single-beat method using three-dimensional echocardiography at rest and during dobutamine stress (20 μg/kg/min). Effective arterial elastance (Ea) was calculated as left ventricular (LV) end-systolic pressure divided by stroke volume, and VA coupling was calculated as Ea/Ees. Event-free survival was then tracked for 32 months. At baseline, VA coupling was far from optimal in patients with DCM compared with controls (Ea/Ees: 2.49 ± 1.02 vs. 1.04 ± 0.21, P < 0.001). During the follow-up period, 22 patients developed adverse cardiovascular events. During dobutamine stress, VA coupling was significantly improved in patients without cardiovascular events (from 2.47 ± 1.09 to 1.59 ± 0.68, P < 0.001), but remained unchanged in those with cardiovascular events. A multivariate Cox proportional-hazards analysis revealed that age, NYHA functional class (>II), and the change in VA coupling during dobutamine stress were the independent determinants of cardiovascular events (P < 0.05, <0.01, and <0.001, respectively). When patients were divided into two subgroups based on the finding of receiver operating characteristic curve analysis, patients with good VA coupling reserve (cut-off: change in VA coupling> 0.29) showed significantly favourable event-free survival than those with poor VA coupling reserve (P < 0.001).

CONCLUSIONS

Improvement in VA coupling during dobutamine stress is an important determinant of cardiovascular outcome for patients with DCM.

Modeling structural and functional deficiencies of RBM20 familial dilated cardiomyopathy using human induced pluripotent stem cells

Dilated cardiomyopathy (DCM) is a leading cause of heart failure. In families with autosomal-dominant DCM, heterozygous missense mutations were identified in RNA-binding motif protein 20 (RBM20), a spliceosome protein induced during early cardiogenesis. Dermal fibroblasts from two unrelated patients harboring an RBM20 R636S missense mutation were reprogrammed to human induced pluripotent stem cells (hiPSCs) and differentiated to beating cardiomyocytes (CMs). Stage-specific transcriptome profiling identified differentially expressed genes ranging from angiogenesis regulator to embryonic heart transcription factor as initial molecular aberrations. Furthermore, gene expression analysis for RBM20-dependent splice variants affected sarcomeric (TTN and LDB3) and calcium (Ca(2+)) handling (CAMK2D and CACNA1C) genes. Indeed, RBM20 hiPSC-CMs exhibited increased sarcomeric length (RBM20: 1.747 ± 0.238 µm versus control: 1.404 ± 0.194 µm; P < 0.0001) and decreased sarcomeric width (RBM20: 0.791 ± 0.609 µm versus control: 0.943 ± 0.166 µm; P < 0.0001). Additionally, CMs showed defective Ca(2+) handling machinery with prolonged Ca(2+) levels in the cytoplasm as measured by greater area under the curve (RBM20: 814.718 ± 94.343 AU versus control: 206.941 ± 22.417 AU; P < 0.05) and higher Ca(2+) spike amplitude (RBM20: 35.281 ± 4.060 AU versus control:18.484 ± 1.518 AU; P < 0.05). β-adrenergic stress induced with 10 µm norepinephrine demonstrated increased susceptibility to sarcomeric disorganization (RBM20: 86 ± 10.5% versus control: 40 ± 7%; P < 0.001). This study features the first hiPSC model of RBM20 familial DCM. By monitoring human cardiac disease according to stage-specific cardiogenesis, this study demonstrates RBM20 familial DCM is a developmental disorder initiated by molecular defects that pattern maladaptive cellular mechanisms of pathological cardiac remodeling. Indeed, hiPSC-CMs recapitulate RBM20 familial DCM phenotype in a dish and establish a tool to dissect disease-relevant defects in RBM20 splicing as a global regulator of heart function.

Stress echocardiography

Stress echocardiography is the combination of 2D echocardiography with a physical, pharmacological or electrical stress. The diagnostic end point for the detection of myocardial ischemia is the induction of a transient worsening in regional function during stress. Stress echocardiography provides similar diagnostic and prognostic accuracy as radionuclide stress perfusion imaging but at a substantially lower cost, without environmental impact and with no biohazards for the patient and the physician. In spite of its dependence upon operator's training, it is the best possible choice to achieve the still elusive target of sustainable cardiac imaging in the field of noninvasive diagnosis of coronary artery disease.

Role of echocardiography in the contemporary management of chronic heart failure

Echocardiography is an excellent noninvasive tool for the assessment of ventricular size and both systolic and diastolic function, and it is routinely used in patients with heart failure. This review will discuss the role of echocardiography in heart failure diagnosis, prognostic assessment and in the management of heart failure patients.

Prognostic value of left atrial volume in patients with dilated cardiomyopathy

BACKGROUND

Increased left atrial (LA) size is a prognostic marker of mortality in the general population. LA size varies considerably in patients with dilated cardiomyopathy (DCM), but its clinical significance has not been widely studied.

OBJECTIVE

To evaluate the long-term prognostic value of LA volume (LAV) in patients with DCM.

METHODS

We prospectively studied patients admitted from January to December 2004 with a diagnosis of DCM, in sinus rhythm. Complete echocardiographic study at rest and after pharmacological stress was performed in all patients. The composite endpoint of mechanical ventricular assistance (MVA), heart transplantation or death during follow-up was assessed by univariate and multivariate analysis using a Cox regression model.

RESULTS

The study population consisted of 35 patients (68.6% male, mean age 52.0) with DCM, 82.9% of non-ischemic etiology. Ejection fraction (EF) at rest was 31.1 ± 9.4%. During follow-up, eight patients died, one was placed on MVA and one underwent transplantation. Univariate Cox analysis showed various potential echocardiographic markers of prognosis in our population, including LA size in M-mode (HR 1.12, CI: 0.99-1.26, p=0.067), LAV (HR 1.03, CI: 1.00-1.07, p=0.046), LAV adjusted for body surface area (HR 1.03, CI: 0.99-1.26, p=0.049), E/A ratio (HR 0.99; CI: 0.99-1.81; p=0.060); E/A >2 (HR 7.00, CI: 1.48-32.43, p=0.014) and mitral E/E' ratio (HR 1.04, CI: 1.00-1.09, p=0.074). The only variable that remained in the multivariate model was LAV, with a cut-off value of 63 ml (HR 7.7, CI: 0.97-60.61, p=0.05).

CONCLUSIONS

LAV was the only echocardiographic determinant of MVA, heart transplantation or death in our population with DCM. The echocardiographic parameters commonly used for risk stratification such as EF, left ventricular end-diastolic diameter and contractile reserve did not show prognostic significance in our study.

Feasibility of semi-quantitative assessment of left ventricular contractile reserve in dilated cardiomyopathy

BACKGROUND

We and others have shown previously that left ventricular (LV) contractile reserve assessed quantitatively by high-dose dobutamine stress-echocardiography (DSE) has prognostic implications in patients with dilated cardiomyopathy.

PURPOSE

To assess the feasibility of semi-quantitative assessment of LV contractile reserve by differently skilled operators in patients with dilated cardiomyopathy.

METHODS

High-dose DSE was performed in 63 consecutive patients, mean age 50 ± 10 years and ejection fraction (EF) 19 ± 8%. LVEF was calculated 1) using Simpson's biplane formula, and 2) semi-quantitatively (5% increments) by novice and experienced echocardiographers, and by a DSE expert. Patients were considered to have preserved LV contractile reserve if LVEF dobutamine-induced change was ≥5%.

RESULTS

Twenty-seven (45.8%) patients died during the 5-year follow-up. The feasibility of the assessment was 89%, 94%, and 98% for novice and experienced readers and DSE expert, respectively. Kaplan-Meier analysis showed that LV contractile reserve assessed semi-quantitatively by DSE expert and experienced reader achieved the best prognostic separation (log rank 19.63 and 18.99, respectively, p < 0.001 for both), followed by quantitative assessment (log rank 9.76, p = 0.0018) and assessment by novice reader (log rank 8.76, p = 0.012). Areas under the curves were similar for quantitative and semi-quantitative assessment of LV contractile reserve.

CONCLUSIONS

Our data indicate that semi-quantitative assessment of LV contractile reserve is feasible by differently skilled operators.

Subclinical myocardial dysfunction in patients with reverse-remodeled dilated cardiomyopathy

BACKGROUND

The aim of this study was to test the hypothesis that patients with reverse-remodeled dilated cardiomyopathy (DCM), whose ejection fractions (EFs) were normalized after optimal pharmacologic therapy, had subclinical myocardial dysfunction.

METHODS

Thirty-two patients with reverse-remodeled DCM, defined as having an initial EF ≤ 35%, which then recovered to ≥50% after optimal pharmacologic therapy, and 11 normal controls with preserved EFs were retrospectively studied. Averaged peak systolic and early diastolic radial, circumferential, and longitudinal speckle-tracking strain rates were assessed from an 18-segment left ventricular model. Similarly, averaged peak systolic radial, circumferential, and longitudinal speckle-tracking strain was obtained.

RESULTS

Peak systolic and early diastolic longitudinal strain rates, peak systolic and early diastolic circumferential strain rates, and peak circumferential and longitudinal strain in patients with reverse-remodeled DCM were significantly lower than those in normal controls, but peak systolic and early diastolic radial strain rates and peak radial strain in patients with reverse-remodeled DCM were similar to those in normal controls. Isometric handgrip stress testing showed a significant decrease in EF from 56 ± 5% to 51 ± 5% (P < .001). Of note, the increase of afterload resulting from isometric handgrip stress testing was associated with a decrease in peak systolic circumferential and longitudinal strain rates and peak circumferential strain in patients with reverse-remodeled DCM.

CONCLUSIONS

The circumferential and longitudinal myocardial function of patients with reverse-remodeled DCM is lower compared with that of normal controls with preserved EFs. Furthermore, the increase in afterload was associated with the decrease in circumferential and longitudinal myocardial systolic function. These findings suggest that in treated patients with DCM with reverse remodeling, left ventricular mechanics may not be normal, even when EFs are normal.

Low-dose dobutamine test associated with interventricular dyssynchrony: a useful tool to identify cardiac resynchronization therapy responders: data from the LOw dose DObutamine stress-echo test in Cardiac Resynchronization Therapy (LODO-CRT) phase 2 study

BACKGROUND

Cardiac resynchronization therapy (CRT) is effective in patients with heart failure, but 30% to 50% of subjects are classified as nonresponders. Identifying responders remains a challenging task.

AIMS

The LODO-CRT trial investigated the association between left ventricular contractile reserve (LVCR) and clinical and echocardiographic long-term CRT response.

METHODS

This is a multicenter, prospective, observational study. Left ventricular contractile reserve was detected using a dobutamine stress echocardiography test, defined as an ejection fraction increase of >5 points. Clinical CRT response was defined as the absence of major cardiovascular events (ie, cardiovascular death or heart failure hospitalization). Echocardiographic response was defined as a left ventricle end-systolic volume reduction of >10%.

RESULTS

A total of 221 CRT-indicated patients were studied (80% presented LVCR). During a mean follow-up of 15 ± 5 months, 17 patients died and 16 were hospitalized due to heart failure. The proportion of clinical responders was 155 (88%) of 177 and 33 (75%) of 44 (P = .036) in the groups with and without LVCR, respectively. Kaplan-Meier analysis showed a significant difference in cardiac survival/hospitalization between patients with and without LVCR. The proportion of echocardiographic responders was 144 (87%) of 166 and 16 (42%) of 38 in the groups with and without LVCR (P < .001), respectively; LVCR showed 90% sensitivity and 87% positive predictive value to prefigure echocardiographic CRT responders. Multivariable analysis identified LVCR and interventricular dyssynchrony as independent predictors of CRT response. The concomitant presence of both factors showed 99% specificity and 83% sensitivity in detecting responders.

CONCLUSION

The presence of LVCR helps in predicting a clinical and echocardiographic CRT response. Concomitant assessment of LVCR and interventricular dyssynchrony accurately stratifies responder and nonresponder patients.

Prognostic significance of right ventricular dimension on acute decompensation in chronic left-sided heart failure

Right ventricular (RV) dysfunction has been discussed in relation to an adverse outcome in heart failure (HF). The aim of this study was to analyze the relationship between RV function with HF exacerbation and its subsequent long-term outcome in patients with chronic left-sided HF.We studied 122 consecutive patients who were admitted for dyspnea due to exacerbated left-sided HF with a left ventricular (LV) ejection fraction of less than 40%. Conventional echocardiography was performed in the study subjects on admission and at discharge. Cox proportional hazards analysis revealed that RV end-diastolic dimension (RVDd) (hazard ratio 1.131, P = 0.005, 95% confidence interval 1.039-1.231) and the serum level of creatinine on admission were independent predictors of subsequent cardiac-related death, but RVDd at discharge and other LV parameters were not. Thus, patients were divided into tertiles on the basis of RVDd on admission: < 32 mm (n = 37), 32-40 mm (n = 43), and ≥ 40 mm (n = 42). According to the increase in the RVDd category, the cardiac-related death-free rate significantly decreased. Among the 3 groups, the pulse pressure and serum total bilirubin levels that demonstrated low cardiac output syndrome (LOS) parameters had significant differences.RVDd on admission could be measured noninvasively and easily to predict a worse long-term prognosis of chronic left-sided HF on admission, and showed correlations with LOS parameters.

Distinct pathophysiological mechanisms of cardiomyopathy in hearts lacking dystrophin or the sarcoglycan complex

Duchenne muscular dystrophy (DMD) and limb girdle muscular dystrophy (LGMD) 2C-F result from the loss of dystrophin and the sarcoglycans, respectively. Dystrophin, a cytoskeletal protein, is closely associated with the membrane-bound sarcoglycan complex. Despite this tight biochemical association, the function of dystrophin and the sarcoglycan subunits may differ. The loss of dystrophin in skeletal muscle results in muscle that is highly susceptible to contraction-induced damage, but the skeletal muscle of mice lacking γ- or δ-sarcoglycan are less susceptible. Using mouse models of DMD, LGMD-2C, and LGMD-2F, we demonstrate that isolated cardiac myocytes from mice lacking either γ- or δ-sarcoglycan have normal compliance. In contrast, dystrophin-deficient myocytes display poor passive compliance and are susceptible to terminal contracture following mild passive extensions. Mice deficient in dystrophin and, less so, δ-sarcoglycan have reduced survival during in vivo dobutamine stress testing compared to controls. Catheter-based hemodynamic studies show deficits in both baseline and dobutamine-stimulated cardiac function in all of the dystrophic mice compared to control mice, with dystrophin-deficient mice having the poorest function. In contrast, histopathology showed increased fibrosis in the sarcoglycan-deficient hearts, but not in hearts lacking dystrophin. In summary, this study provides important insights into the unique mechanisms of disease underlying these different models of inherited dystrophic cardiomyopathy and supports a model where dystrophin, but not the sarcoglycans, protects the cardiac myocyte against mechanical damage.

The concept of ventricular reserve in heart failure and pulmonary hypertension: an old metric that brings us one step closer in our quest for prediction

PURPOSE OF REVIEW

Ventricular reserve is emerging a strong predictor of outcome in heart failure and cardiovascular disease. Ventricular reserve is the term used to describe the extent of increase or change in ventricular function that occurs during exercise or pharmacological stress (typically with dobutamine).

RECENT FINDINGS

The interest in ventricular reserve lies in its ability to assess viability in coronary artery disease, to predict clinical outcome and response to therapy in patients with heart failure and to screen patients for early cardiovascular disease.

SUMMARY

In this paper, we will review the emerging role of ventricular reserve in heart failure and pulmonary hypertension. We will also explore the mechanisms involved in the pathophysiology of impaired ventricular reserve and discuss future directions of research in the field.

Assessment of cardiac dynamics during stress echocardiography by the peak power output-to-left ventricular mass ratio

Peak cardiac power-to-mass and peak mass-to-power are variables that couple cardiac power output with left ventricular (LV) mass at peak exercise or during maximal inotropic stimulation. Quantitative stress echocardiography enables the calculation of power output according to the formula: 133 × 10–6 × stroke volume per second (ml) × mean blood pressure (BP; mmHg) × heart rate. Power-to-mass may be calculated as LV power output per 100 g of LV mass: 100 g × LV power output divided by LV mass (W/100 g). Conversely, mass-to-power may be estimated by dividing LV mass index by LV power output (g/m2/W). With a little rearrangement of the formulas we can write: power-to-mass (W/100 g) = 0.222 × cardiac output (l/min) × mean BP (mmHg)/LV mass (g) and mass-to-power (g/m2/W) = LV mass index/0.00222 × cardiac output (l/min) × mean BP (mmHg). These parameters reflect the energy delivery of ventricular myocardium with respect to potential energy that is stored in LV mass. The assessment of peak power-to-mass and peak mass-to-power indices may be useful to distinguish compensatory versus maladaptive remodeling in patients with LV dysfunction. When the integrity of myocardial structure is compromised, a disproportion becomes apparent between maximal cardiac power output and LV mass and this leads to either a reduction of peak power-to-mass or an increase of peak mass-to-power. Preliminary reports have demonstrated the usefulness and the prognostic value of peak power-to-mass and peak mass-to-power in patients with LV systolic dysfunction and coronary artery disease.

Clinical and prognostic role of pressure-volume relationship in the identification of responders to cardiac resynchronization therapy

BACKGROUND

The identification of responders remains challenging in cardiac resynchronization therapy (CRT). Pressure-volume relationship (PVR) is a method to evaluate left ventricular myocardial contractility during stress. The aim of the study was to assess the role of PVR to identify responders to CRT.

METHODS

Seventy-two patients (57% with ischemic etiology) referred to CRT: ejection fraction ≤ 35%, New York Heart Association ≥ III and QRS duration ≥ 120 milliseconds, underwent dobutamine stress echocardiography (up to 40 μg/kg per minute). PVR was defined as systolic cuff pressure/end-systolic volume index difference between rest-peak dobutamine stress echocardiography. Responders were identified by clinical and/or echocardiographic (end-systolic volume decrease ≥ 15%) follow-up criteria. We divided retrospectively the patient population into 2 groups, accordingly to the presence of myocardial contractile reserve that was set at the value of PVR (0.72 mm Hg/mL per square meter) obtained by a receiver operating characteristic analysis.

RESULTS

During a median follow-up of 12 months, 8 patients (11%) died. Patients with lower PVR, showed higher brain natriuretic peptide levels (853 ± 1211 vs 342 ± 239, P = .044) larger left ventricular end-diastolic (196 ± 82 mL vs 152 ± 39 mL, P = .005) and end-systolic (147 ± 66 vs 112 ± 30 mL, P = .006) volumes. Intraventricular dyssynchrony was similar in the 2 groups (88 ± 45 vs 70 ± 32 milliseconds, P = .175). Patients with higher PVR presented a larger incidence of clinical (86% vs 46% P < .001), and echocardiographic responders to CRT (79% vs 40%, P = .002). Event-free survival was significantly better in patients with higher PVR (log rank = 5.78, P = .01).

CONCLUSION

Patients with preserved contractility, assessed by PVR during stress echocardiography show a favor clinical outcome and left ventricular reverse remodeling after CRT. In particular, PVR may have a significant clinical role in patients undergoing CRT, providing critical information for risk stratification.

Right ventricular pressure dynamics and stress echocardiography in pharmacological and exercise stress testing

REASONS FOR PERFORMING STUDY

There is interest in using pharmacological stress testing (PST) as a substitute for exercise stress testing (EST) to evaluate cardiac function in horses.

OBJECTIVES

To compare the effect of PST and EST on right ventricular pressure dynamics and stress echocardiography.

METHODS

Five horses completed a PST and EST in a randomised crossover design. High fidelity pressure transducers were placed in the right ventricle. Continuous pressure signals were digitally collected and stored, and dP/dtmax, dP/dtmin and tau calculated from these measurements. ECGs were recorded continuously for 20 h. Echocardiography was performed prior to EST and PST, during and after PST, and immediately post EST. Plasma cardiac troponin I concentrations were measured pre- and 3-4 h post stress testing. For PST, 5 microg/kg bwt glycopyrrolate i.v. followed after 10 min by 5 microg/kg bwt/min dobutamine infusion over 10 min was given. EST consisted of a 2 min gallop at 110% speed required to elicit VO2max.

RESULTS

Both EST and PST resulted in a significant increase in right-ventricular dP/dtmax and dP/dtmin over baseline (P<0.05) and a significant decrease in tau compared with baseline (P<0.05). EST dP/dtmax and dP/dtmin were significantly greater than PST dP/dtmax and dP/dtmin (P<0.05) and EST tau was significantly less than PST tau (P<0.05). Two minutes post EST and 5 min post PST dP/dtmax were not significantly different, but were significantly less than end-EST and during PST. Tau was also not significantly different between post EST and post PST, but was significantly decreased end-EST compared with during PST. FS were not significantly different between PST and post EST, but during PST and post EST all FS were significantly higher than baseline. Cardiac troponin I concentrations were significantly elevated post PST and were greater than post EST. The clinical relevance of this is unknown.

CONCLUSIONS

PST had a similar, although less marked effect on the cardiac parameters related to right-ventricular pressure dynamics and a similar effect on echocardiography as exercise stress testing.

POTENTIAL RELEVANCE

PST deserves further evaluation in normal horses and those with cardiac disease, and may be complementary to EST to better identify exercise-induced cardiac dysfunction.

The role of echocardiography in guiding management in dilated cardiomyopathy

Dilated cardiomyopathy (DCM) is a common and malignant condition, which carries a poor long-term prognosis. Underlying disease aetiologies are varied, and often carry specific implications for treatment and prognosis. The role of echocardiography is essential in not only establishing the diagnosis, but also in defining the aetiology, and understanding the pathophysiology. This article therefore explores the pivotal role of echocardiography in the evaluation and management of patients with DCM.

Identification of responders to cardiac resynchronization therapy by contractile reserve during stress echocardiography

AIMS

The identification of responders to cardiac resynchronization therapy (CRT) remains a challenge. We assessed the role of dyssynchrony (DYS) and contractile reserve (CR) in identifying CRT responders.

METHODS AND RESULTS

Sixty-nine patients (55% with ischaemic aetiology) referred for CRT (ejection fraction < or =35%, New York Heart Association > or =III, and QRS duration > or =120 ms) underwent baseline evaluation of DYS and dobutamine stress-echo [up to 40 microg/kg/min: CR was defined as a wall motion score index (WMSI) variation > or =0.20]. CRT responders were identified by clinical and/or echocardiographic [end-systolic volume (ESV) decrease > or =15%] follow-up criteria. During a median follow-up of 11 months, 46 patients (66%) were classified as clinical responders. Reverse remodelling was found in 34 of the 59 patients (58%) with echocardiographic follow-up. CR was present in 78% of clinical responders (P = 0.001) and in 69% with reverse remodelling (P = 0.005). DYS was equally present in the two groups. Reverse remodelling was correlated with rest-stress changes in ESV (r = 0.439, P = 0.003) and in WMSI (r = 0.450, P = 0.001), but not with DYS. CR (OR = 6.2, 95% CI = 1.4-27.6, P = 0.015) was the best predictor of response to CRT.

CONCLUSION

Patients with CR show a favourable clinical and reverse LV remodelling response to CRT. This finding shifts the focus from electrical (dyssynchrony) to the myocardial substrate of functional response.

Native cardiac reserve predicts survival in acute post infarction heart failure in mice

Cardiac reserve can be used to predict survival and outcome in patients with heart failure. The aim of this study was to investigate if native cardiac reserve could predict survival after myocardial infarction (MI) in mice.

METHOD

We investigated 27 healthy C57Bl6 mice (male symbol10-12 weeks old) with echocardiography using a high-frequency 15-MHz linear transducer. Investigations were performed both at rest and after pharmacological stress induced by dobutamine (1 mug/g body weight i.p.). The day after the echocardiography examination, a large MI was induced by ligation of the left anterior descending (LAD) coronary artery for evaluation of mortality rate.

RESULTS

Two weeks after induction of MI, 7 mice were alive (26%). Evaluation of the difference between the surviving and deceased animals showed that the survivors had a better native ability to increase systolic performance (DeltaLVESd -1.86 vs -1.28mm p = 0.02) upon dobutamine challenge, resulting in a better cardiac reserve (DeltaFS 37 vs 25% p = 0.02 and DeltaCO 0.27 vs -0.10 ml/min p = 0.02) and a better chronotropic reserve (DeltaR-R interval -68 vs -19 ms p < 0.01). A positive relationship was found between ability to survive and both cardiac (p < 0.05) and chronotropic reserve (p < 0.05) when the mice were divided into three groups: survivors, surviving < 7 days, and surviving < 1 day.

CONCLUSION

We conclude that before MI induction the surviving animals had a better cardiac function compared with the deceased. This indicates that native cardiac and chronotropic reserve may be an important determinant and predictor of survival in the setting of large MI and post-infarction heart failure.