Size, shape, and stamina: the impact of left ventricular geometry on exercise capacity

Left ventricular volume and maximal functional capacity in heart failure with preserved ejection fraction: Size matters

AIMS

Emerging evidence suggests that smaller left ventricular volumes may identify subjects with lower cardiorespiratory fitness. Whether left ventricular size predicts functional capacity in patients with heart failure with preserved ejection fraction (HFpEF) is unclear. This study aimed to explore the association between indexed left ventricular end-diastolic volume (iLVEDV) and maximal functional capacity, assessed by peak oxygen consumption (peakVO2), in stable outpatients with HFpEF.

METHODS AND RESULTS

We prospectively analysed data from 133 consecutive stable outpatients who underwent cardiopulmonary exercise testing and echocardiography on the same day. Data were validated in a cohort of HFpEF patients from San Paolo Hospital, Milan, Italy. A multivariable linear regression assessed the association between iLVEDV and peakVO2. The mean age was 73.2 ± 10.5 years, and 75 (56.4%) were women. The median iLVEDV, indexed left ventricular end-systolic volume, and left ventricular ejection fraction were 46 ml/m2 (30-56), 15 ml/m2 (11-19), and 66% (60-74%), respectively. The median peakVO2 and percentage of predicted peakVO2 were 11 ml/kg/min (9-13) and 64.1% (53-74.4), respectively. Adjusted linear regression analysis showed that smaller iLVEDV was associated with lower peakVO2 (p = 0.0001). In the validation cohort, adjusted linear regression analysis showed a consistent pattern: a smaller iLVEDV was associated with a higher likelihood of reduced peakVO2 (p = 0.004).

CONCLUSIONS

In stable outpatients with HFpEF, a smaller iLVEDV was associated with a lower maximal functional capacity. These findings suggest a need for further studies to understand the pathophysiological mechanisms underlying these observations and to explore targeted treatment strategies for this patient subgroup.

Association of body adiposity with left ventricular concentric remodeling and diastolic dysfunction

BACKGROUND

Obesity is a significant risk factor for heart failure with preserved ejection fraction (HFpEF). In this study, we explore the relationships between body mass index (BMI) and adipose tissue compartments such as visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and epicardial adipose tissue (EAT), with respect to left ventricular (LV) structure and function in subjects with preserved LV systolic function.

METHODS

Between January and December 2020, this retrospective study included 749 participants who exhibited preserved LV systolic function and underwent transthoracic echocardiography along with abdominal computed tomography. LV structural and functional variables as well as EAT, VAT, and SAT thickness were evaluated using echocardiography and computed tomography.

RESULTS

SAT decreased, while VAT and EAT progressively increased with age. There were significant correlations between BMI and various adipose tissues, with the strongest correlation observed with SAT (r = .491, p < .001) compared to VAT (r = .371, p < .001) or EAT (r = .135, p < .001). However, EAT demonstrated the most substantial association with decreased LV end-diastolic dimension, LV end-systolic dimension, and septal mitral annular velocity and increased relative wall thickness (all p < .05), while VAT and SAT did not show significant associations with LV remodeling and functional parameters after adjusting for clinical variables.

CONCLUSION

EAT is the most critical adipose tissue influencing LV geometric and functional changes, compared with VAT or SAT. Thick EAT is associated small LV chamber size, concentric remodeling, and relaxation abnormalities.

Too Little of a Good Thing: Strong Associations Between Cardiac Size and Fitness Among Women

BACKGROUND

Cardiorespiratory fitness (CRF) is associated with functional impairment and cardiac events, particularly heart failure (HF). However, the factors predisposing women to low CRF and HF remain unclear.

OBJECTIVES

This study sought to evaluate the association between CRF and measures of ventricular size and function and to examine the potential mechanism linking these factors.

METHODS

A total of 185 healthy women aged >30 years (51 ± 9 years) underwent assessment of CRF (peak volume of oxygen uptake [Vo2peak]) and biventricular volumes at rest and during exercise by using cardiac magnetic resonance (CMR). The relationships among Vo2peak, cardiac volumes, and echocardiographic measures of systolic and diastolic function were assessed using linear regression. The effect of cardiac size on cardiac reserve (change in cardiac function during exercise) was assessed by comparing quartiles of resting left ventricular end-diastolic volume (LVEDV).

RESULTS

Vo2peak was strongly associated with resting measures of LVEDV and right ventricular end-diastolic volume (R2 = 0.58-0.63; P < 0.0001), but weakly associated with measures of resting left ventricular (LV) systolic and diastolic function (R2 = 0.01-0.06; P < 0.05). Increasing LVEDV quartiles were positively associated with cardiac reserve, with the smallest quartile showing the smallest reduction in LV end-systolic volume (quartile [Q]1: -4 mL vs Q4: -12 mL), smallest augmentation in LV stroke volume (Q1: +11 mL vs Q4: +20 mL) and cardiac output (Q1: +6.6 L/min vs Q4: +10.3 L/min) during exercise (interaction P < 0.001 for all).

CONCLUSIONS

A small ventricle is strongly associated with low CRF because of the combined effect of a smaller resting stroke volume and an attenuated capacity to increase with exercise. The prognostic implications of low CRF in midlife highlight the need for further longitudinal studies to determine whether women with small ventricles are predisposed to functional impairment, exertional intolerance, and HF later in life.

Effect of Sacubitril/Valsartan vs Valsartan on Left Atrial Volume in Patients With Pre-Heart Failure With Preserved Ejection Fraction: The PARABLE Randomized Clinical Trial

Importance

Pre-heart failure with preserved ejection fraction (pre-HFpEF) is common and has no specific therapy aside from cardiovascular risk factor management.

Objective

To investigate the hypothesis that sacubitril/valsartan vs valsartan would reduce left atrial volume index using volumetric cardiac magnetic resonance imaging in patients with pre-HFpEF.

Design, Setting, and Participants

The Personalized Prospective Comparison of ARNI [angiotensin receptor/neprilysin inhibitor] With ARB [angiotensin-receptor blocker] in Patients With Natriuretic Peptide Elevation (PARABLE) trial was a prospective, double-blind, double-dummy, randomized clinical trial carried out over 18 months between April 2015 and June 2021. The study was conducted at a single outpatient cardiology center in Dublin, Ireland. Of 1460 patients in the STOP-HF program or outpatient cardiology clinics, 461 met initial criteria and were approached for inclusion. Of these, 323 were screened and 250 asymptomatic patients 40 years and older with hypertension or diabetes, elevated B-type natriuretic peptide (BNP) greater than 20 pg/mL or N-terminal pro-b type natriuretic peptide greater than 100 pg/mL, left atrial volume index greater than 28 mL/m2, and preserved ejection fraction greater than 50% were included.

Interventions

Patients were randomized to angiotensin receptor neprilysin inhibitor sacubitril/valsartan titrated to 200 mg twice daily or matching angiotensin receptor blocker valsartan titrated to 160 mg twice daily.

Main Outcomes and Measures

Maximal left atrial volume index and left ventricular end diastolic volume index, ambulatory pulse pressure, N-terminal pro-BNP, and adverse cardiovascular events.

Results

Among the 250 participants in this study, the median (IQR) age was 72.0 (68.0-77.0) years; 154 participants (61.6%) were men and 96 (38.4%) were women. Most (n = 245 [98.0%]) had hypertension and 60 (24.0%) had type 2 diabetes. Maximal left atrial volume index was increased in patients assigned to receive sacubitril/valsartan (6.9 mL/m2; 95% CI, 0.0 to 13.7) vs valsartan (0.7 mL/m2; 95% CI, -6.3 to 7.7; P < .001) despite reduced markers of filling pressure in both groups. Changes in pulse pressure and N-terminal pro-BNP were lower in the sacubitril/valsartan group (-4.2 mm Hg; 95% CI, -7.2 to -1.21 and -17.7%; 95% CI, -36.9 to 7.4, respectively; P < .001) than the valsartan group (-1.2 mm Hg; 95% CI, -4.1 to 1.7 and 9.4%; 95% CI, -15.6 to 4.9, respectively; P < .001). Major adverse cardiovascular events occurred in 6 patients (4.9%) assigned to sacubitril/valsartan and 17 (13.3%) assigned to receive valsartan (adjusted hazard ratio, 0.38; 95% CI, 0.17 to 0.89; adjusted P = .04).

Conclusions and Relevance

In this trial of patients with pre-HFpEF, sacubitril/valsartan treatment was associated with a greater increase in left atrial volume index and improved markers of cardiovascular risk compared to valsartan. More work is needed to understand the observed increased cardiac volumes and long-term effects of sacubitril/valsartan in patients with pre-HFpEF.

Trial Registration

ClinicalTrials.gov Identifier: NCT04687111.

Detailed investigation of multiple resting cardiovascular parameters in relation to physical fitness

OBJECTIVE

Maximal oxygen consumption at an exercise test (VO₂ -max) is a commonly used marker of physical fitness. In the present study, we aimed to find independent clinical predictors of VO₂ -max by use of multiple measurements of cardiac, respiratory and vascular variables collected while resting.

METHODS

In the Prospective study of Obesity, Energy and Metabolism (POEM), 420 subjects aged 50 years were investigated regarding endothelial function, arterial compliance, heart rate variability, arterial blood flow and atherosclerosis, left ventricular structure and function, lung function, multiple blood pressure measurements, lifestyle habits, body composition and in addition a maximal bicycle exercise test with gas exchange (VO₂ and VCO₂ ).

RESULTS

When VO₂ -max (indexed for lean mass) was used as the dependent variable and the 84 hemodynamic or metabolic variables were used as independent variables in separate sex-adjusted models, 15 variables showed associations with p < 0.00064 (Bonferroni-adjusted). Eight independent variables explained 21% of the variance in VO₂ -max. Current smoking and pulse wave velocity (PWV) were the two major determinants of VO₂ -max (explaining each 7% and 3% of the variance; p < 0.0001 and p = 0.008, respectively). They were in order followed by vital capacity, fat mass, pulse pressure, and high-density lipoprotein (HDL)-cholesterol. The relationships were inverse for all these variables, except for vital capacity and HDL.

CONCLUSION

Several metabolic, cardiac, respiratory and vascular variables measured at rest explained together with smoking 21% of the variation in VO₂ -max in middle-aged individuals. Of those variables, smoking and PWV were the most important.

Recognized and Unrecognized Value of Echocardiography in Guideline and Consensus Documents Regarding Patients With Chest Pain

Guideline and consensus documents have recently been published on the important topic of the noninvasive evaluation of patients presenting with chest pain (CP) or patients with known acute or chronic coronary syndromes. Authors for these documents have included members representing multispecialty imaging societies, yet the process of generating consensus and the need to produce concise written documents have led to a situation where the particular advantages of echocardiography are overlooked. Broad guidelines such as these can be helpful when it comes to "when to do" noninvasive cardiac testing, but they do not pretend to offer nuances on "how to do" noninvasive cardiac testing. This report details the particular value of echocardiography and potential explanations for its understated role in recent guidelines. This report is categorized into the following sections: (1) impact of the level of evidence on guideline creation; (2) versatility of echocardiography in the assessment of CP and the inimitable role for echo Doppler echocardiography in the assessment of dyspnea; (3) value of point-of-care ultrasound in assessing CP and dyspnea; and (4) the future role of echocardiography in ischemic heart disease.

Preoperative Evaluation and Cardiac Risk Assessment in Vascular Surgery

We summarize epidemiologic trends, outcomes, and preoperative guidelines for vascular surgery patients from 2010 to 2022. Vascular surgery continues to evolve in technology and engineering to treat a surgical population that suffers from a high prevalence of comorbidities. Preoperative optimization seeks to characterize the burden of disease and to achieve medical control in the timeline available before surgery. Risk assessment, evaluation, optimization, and prediction of major adverse cardiac events is an evolving science where the Vascular Surgery Quality Initiative has made an impact. Ongoing investigation may demonstrate value for preoperative echocardiography, functional capacity, frailty, and mobility assessments.

Relationship between Coronary Artery Tortuosity and Cardiorespiratory Fitness in Patients without Obstructed Coronaries

OBJECTIVE

This study aimed to analyze the relationship between cardiorespiratory fitness (CRF) and the increasing severity of coronary artery tortuosity (CAT) in patients with non-stenosed coronaries.

METHODS

A total of 396 patients who underwent coronary angiography and cardiopulmonary exercise testing (CPET) between August 2020 and July 2021 were included in this single-center retrospective study after excluding patients with significant coronary artery disease (≥50% stenosis). Patients were divided into two groups: no or mild coronary artery tortuosity (N/M-CAT) and moderate to severe coronary artery tortuosity (M/S-CAT) and laboratory electrocardiographic, echocardiographic, and CPET parameters were compared between two groups.

RESULTS

M/S-CAT was found in 46.9% of the study participants, with 66.7% being women. M/S-CAT was significantly associated with advanced age (P=0.014) and females (P=0.001). Diastolic dysfunction parameters, E velocity (P=0.011), and E/A ratio (P=0.004) also revealed significant differences between the M/S-CAT group and N/M-CAT group. VO₂@peak (1.22±0.39 vs. 1.07±0.39, P<0.01) and VO₂@AT (0.77±0.22 vs. 0.71±0.21, P=0.017) were significantly lower in the M/S-CAT group than in the N/M-CAT group. Multivariate logistic regression analysis identified females (OR=0.448; 95% CI, 0.296-0.676; P=0.000) and E/A ratio (OR=0.307; 95% CI, 0.139-0.680; P=0.004) to be independent risk factors of M/S-CAT and showed no association of CPET parameters to M/S-CAT.

CONCLUSION

The results indicate that increasing severity of CAT is strongly associated with female gender and E/A ratio and is not directly correlated with decreasing CRF. Further research with a larger patient population and a longer follow-up time is required to fully comprehend the impact of CAT on CRF.

Heart Failure With Preserved Ejection Fraction as an Exercise Deficiency Syndrome: JACC Focus Seminar 2/4

Across differing spectrums of cardiac function and cardiac pathologies, there are strong associations between measures of cardiorespiratory fitness and burden of symptoms, quality of life, and prognosis. In this part 2 of a 4-part series, we contend that there is a strong association among physical activity, cardiorespiratory fitness, and cardiac function. We argue that a chronic lack of exercise is a major risk factor for heart failure with preserved ejection fraction in some patients. In support of this hypothesis, increasing physical activity is associated with greater cardiac mass, greater stroke volumes, greater cardiac output and peak oxygen consumption, and fewer clinical events. Conversely, physical inactivity results in cardiac atrophy, reduced output, reduced chamber size, and decreased ability to augment cardiac performance with exercise. Moreover, physical inactivity is a strong predictor of heart failure risk and death. In sum, exercise deficiency should be considered part of the broad heart failure with preserved ejection fraction phenotype.

Association Between Left Ventricular Relative Wall Thickness and Acute Kidney Injury After Noncardiac Surgery

BACKGROUND

Acute kidney injury (AKI) after major noncardiac surgery is commonly attributed to cardiovascular dysfunction. Identifying novel associations between preoperative cardiovascular markers and kidney injury may guide risk stratification and perioperative intervention. Increased left ventricular relative wall thickness (RWT), routinely measured on echocardiography, is associated with myocardial dysfunction and long-term risk of heart failure in patients with preserved left ventricular ejection fraction (LVEF); however, its relationship to postoperative complications has not been studied. We evaluated the association between preoperative RWT and AKI in high-risk noncardiac surgical patients with preserved LVEF.

METHODS

Patients ≥18 years of age having major noncardiac surgery (high-risk elective intra-abdominal or noncardiac intrathoracic surgery) between July 1, 2016, and June 30, 2018, who had transthoracic echocardiography in the previous 12 months were eligible. Patients with preoperative creatinine ≥2 mg/dL or reduced LVEF (<50%) were excluded. The association between RWT and AKI, defined as an increase in serum creatinine by 0.3 mg/dL from baseline within 48 hours or by 50% within 7 days after surgery, was assessed using multivariable logistic regression adjusted for preoperative covariates. An additional model adjusted for intraoperative covariates, which are strongly associated with AKI, especially hypotension. RWT was modeled continuously, associating the change in odds of AKI for each 0.1 increase in RWT.

RESULTS

The study included 1041 patients (mean ± standard deviation [SD] age 62 ± 15 years; 59% female). A total of 145 subjects (13.9%) developed AKI within 7 days. For RWT quartiles 1 through 4, respectively, 20 of 262 (7.6%), 40 of 259 (15.4%), 39 of 263 (14.8%), and 46 of 257 (17.9%) developed AKI. Log-odds and proportion with AKI increased across the observed RWT values. After adjusting for confounders (demographics, American Society of Anesthesiologists [ASA] physical status, comorbidities, baseline creatinine, antihypertensive medications, and left ventricular mass index), each RWT increase of 0.1 was associated with an estimated 26% increased odds of developing AKI (odds ratio [OR]; 95% confidence interval [CI]) of 1.26 (1.09-1.46; P = .002). After adjusting for intraoperative covariates (length of surgery, presence of an arterial line, intraoperative hypotension, crystalloid administration, transfusion, and urine output), RWT remained independently associated with the odds of AKI (OR; 95% CI) of 1.28 (1.13-1.47; P = .001). Increased RWT was also independently associated with hospital length of stay and adjusted hazard ratio (HR [95% CI]) of 0.94 (0.89-0.99; P = .018).

CONCLUSIONS

Left ventricular RWT is a novel cardiovascular factor associated with AKI within 7 days after high-risk noncardiac surgery among patients with preserved LVEF. Application of this commonly available measurement of risk stratification or perioperative intervention warrants further investigation.

The clinical associations with cardiomegaly in patients undergoing evaluation for pulmonary hypertension

Background

Chest radiographs can identify important abnormalities in patients undergoing diagnostic evaluation for cardiovascular diseases. Cardiomegaly often reflects cardiac chamber dilation, or cardiac muscle hypertrophy, or both conditions. The clinical implications of cardiomegaly depend on the underlying clinical disorder. Does cardiomegaly have any clinical, laboratory, echocardiographic, and right heart catheterization associations in patients undergoing evaluation for pulmonary hypertension?

Methods

Patients referred to a pulmonary vascular disease clinic for possible pulmonary hypertension underwent a comprehensive evaluation that included right heart catheterization. These patients also had chest radiographs, laboratory studies, and echocardiograms. The patients were divided into two groups based on the presence or absence of cardiomegaly.

Results

This study included 102 patients (63.7% female) with a mean age of 62.3 ± 15.0 years. Patients with cardiomegaly (n = 64) had elevated BNP, BUN, and creatinine levels. They had elevated right atrial pressures, right ventricular pressures, and pulmonary artery pressures and reduced cardiac indices and reduced mixed venous oxygen saturations. There were no differences in echocardiographic parameters between the two groups.

Conclusions

This study demonstrates that the presence of cardiomegaly on chest radiographs has important clinical implications, including increased BNP levels and increased right heart pressures, in patients undergoing evaluation for pulmonary hypertension. Consequently, the presence of cardiomegaly supports the need for additional evaluation, including right heart catheterization, and provides useful information for primary care physicians and specialists.

Left Ventricular Remodeling and Myocardial Work: Results From the Population-Based STAAB Cohort Study

Introduction: Left ventricular (LV) dilatation and LV hypertrophy are acknowledged precursors of myocardial dysfunction and ultimately of heart failure, but the implications of abnormal LV geometry on myocardial function are not well-understood. Non-invasive LV myocardial work (MyW) assessment based on echocardiography-derived pressure-strain loops offers the opportunity to study detailed myocardial function in larger cohorts. We aimed to assess the relationship of LV geometry with MyW indices in general population free from heart failure.

Methods and Results: We report cross-sectional baseline data from the Characteristics and Course of Heart Failure Stages A-B and Determinants of Progression (STAAB) cohort study investigating a representative sample of the general population of Würzburg, Germany, aged 30–79 years. MyW analysis was performed in 1,926 individuals who were in sinus rhythm and free from valvular disease (49.3% female, 54 ± 12 years). In multivariable regression, higher LV volume was associated with higher global wasted work (GWW) (+0.5 mmHg% per mL/m², p < 0.001) and lower global work efficiency (GWE) (−0.02% per mL/m², p < 0.01), while higher LV mass was associated with higher GWW (+0.45 mmHg% per g/m², p < 0.001) and global constructive work (GCW) (+2.05 mmHg% per g/m², p < 0.01) and lower GWE (−0.015% per g/m², p < 0.001). This was dominated by the blood pressure level and also observed in participants with normal LV geometry and concomitant hypertension.

Conclusion: Abnormal LV geometric profiles were associated with a higher amount of wasted work, which translated into reduced work efficiency. The pattern of a disproportionate increase in GWW with higher LV mass might be an early sign of hypertensive heart disease.

Left Ventricular Geometry in COPD Patients: ARE THERE ASSOCIATIONS WITH AIRFLOW LIMITATION, FUNCTIONAL CAPACITY, AND GRIP STRENGTH?

PURPOSE

Chronic obstructive pulmonary disease (COPD) and abnormalities of left ventricular (LV) geometry often coexist. This study aimed to verify whether LV geometry is associated with airflow obstruction, functional capacity, and grip strength in COPD patients.

METHODS

Thirty-seven COPD patients (GOLD II, III, and IV) were allocated to three groups according to LV geometry as assessed by transthoracic echocardiography: normal (n = 13), concentric LV remodeling (n = 8), and concentric LV hypertrophy (LVH) (n = 16). Lung function was assessed using spirometry. The Duke Activity Status Index (DASI) was used to estimate functional capacity, and grip strength measurement was performed using a hydraulic hand dynamometer.

RESULTS

The concentric LVH group presented lower DASI scores (P = .045) and grip strength (P = .006) when compared with the normal group. Correlations analysis showed the following: relative wall thickness negatively correlated with forced expiratory volume in the first second (r = -0.380; P = .025) and DASI score (r = -0.387, P = .018); LV mass index negatively correlated with grip strength (r = -0.363, P = .038).

CONCLUSIONS

In COPD patients, LV geometry is associated with airflow limitation, functional capacity, and grip strength. Specifically, concentric LV remodeling is associated with increased airflow limitation and decreased functional capacity whereas increased LV mass is associated with decreased grip strength.

Epicardial adipose tissue is tightly associated with exercise intolerance in patients with type 2 diabetes mellitus with asymptomatic left ventricular structural and functional abnormalities

AIMS

This study aimed to elucidate whether the volume of epicardial adipose tissue (EAT) is associated with left ventricular (LV) structural and functional abnormalities and exercise capacity in patients with type 2 diabetes mellitus (T2DM).

METHODS

EAT thickness and LV structural and functional abnormality components (e.g., global longitudinal strain, E/e', LV mass index, relative wall thickness) were measured using echocardiography in 176 patients with asymptomatic stage A and B heart failure (SAHF and SBHF, respectively) and 62 healthy controls (HC). Peak oxygen uptake (peakVO2) was measured by using cardiopulmonary exercise testing.

RESULTS

Even when matching study participants for age, sex, and body mass index, the EAT was thicker (HCs 5.5 ± 1.2 versus SAHF 6.4 ± 1.0 and SBHF 9.3 ± 1.7 mm) and peakVO2 was lower (HC 24.1 ± 3.3 versus SAHF 19.1 ± 2.0 and SBHF 16.9 ± 3.1 ml/kg/min) in the heart failure (HF) group than in the HC group (p < 0.001). EAT thickness (β = -0.189, p < 0.001) and peakVO2 were significantly associated, even after adjusting for multivariates (R² = 0.457).

CONCLUSIONS

In T2DM patients with asymptomatic HF, EAT may be associated with LV structural and functional abnormalities and exercise intolerance.

Diastolic Stress Testing Along the Heart Failure Continuum

PURPOSE OF REVIEW

This review summarizes recent developments highlighting the clinical utility of diastolic stress testing along the heart failure continuum.

RECENT FINDINGS

Invasive hemodynamic assessment of cardiac filling pressures during physiological stress is the gold-standard technique for unmasking diastolic dysfunction. Non-invasive surrogate techniques, such as Doppler ultrasound, have shown excellent agreement with invasive approaches and are now recommended by the American Society of Echocardiography and the European Association of Cardiovascular Imaging. While cycle exercise is often advocated, recent evidence supports the use of isometric handgrip as a viable alternative stressor. Diastolic stress testing is a powerful tool to enhance detection of diastolic dysfunction, is able to differentiate between cardiac and non-cardiac pathology, and should be incorporated into routine clinical assessment.

Mice lacking α-, β1- and β2-syntrophins exhibit diminished function and reduced dystrophin expression in both cardiac and skeletal muscle

Syntrophins are a family of modular adaptor proteins that are part of the dystrophin protein complex, where they recruit and anchor a variety of signaling proteins. Previously we generated mice lacking α- and/or β2-syntrophin but showed that in the absence of one isoform, other syntrophin isoforms can partially compensate. Therefore, in the current study, we generated mice that lacked α, β1 and β2-syntrophins [triple syntrophin knockout (tKO) mice] and assessed skeletal and cardiac muscle function. The tKO mice showed a profound reduction in voluntary wheel running activity at both 6 and 12 months of age. Function of the tibialis anterior was assessed in situ and we found that the specific force of tKO muscle was decreased by 20-25% compared with wild-type mice. This decrease was accompanied by a shift in fiber-type composition from fast 2B to more oxidative fast 2A fibers. Using echocardiography to measure cardiac function, it was revealed that tKO hearts had left ventricular cardiac dysfunction and were hypertrophic, with a thicker left ventricular posterior wall. Interestingly, we also found that membrane-localized dystrophin expression was lower in both skeletal and cardiac muscles of tKO mice. Since dystrophin mRNA levels were not different in tKO, this finding suggests that syntrophins may regulate dystrophin trafficking to, or stabilization at, the sarcolemma. These results show that the loss of all three major muscle syntrophins has a profound effect on exercise performance, and skeletal and cardiac muscle dysfunction contributes to this deficiency.

Maladaptive left ventricular remodeling in women: An analysis from the Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction study

BACKGROUND

Women represent approximately half of heart failure hospitalizations and are disproportionately affected by heart failure with preserved ejection fraction (HFpEF). Women with signs and symptoms of ischemia, preserved left ventricular ejection fraction (LVEF), and no obstructive coronary artery disease (CAD) often have elevated left ventricular end-diastolic pressure (LVEDP). However, isolated elevated LVEDP in the absence of coronary microvascular dysfunction (CMD) is not understood.

METHODS

Among 244 women with signs and symptoms of ischemia, no obstructive CAD, and preserved LVEF who underwent invasive coronary reactivity testing (CRT), 43 (18%) women had no evidence of CMD. LVEDP was measured at time of CRT, and left ventricular (LV) volumes and mass were assessed by cardiac magnetic resonance (CMR) imaging.

RESULTS

Of the 43 women without CMD, 24 (56%) had elevated LVEDP [mean 18 mm Hg (SD = 3)] compared to 19 (44%) with normal LVEDP [11 mm Hg (SD = 3)]. The elevated LVEDP group had a comparatively higher systolic and diastolic blood pressure, lower LV end-diastolic volume index (EDVI), and higher mass-to-volume ratio. Other functional parameters were not significantly different.

CONCLUSIONS

Among women with signs and symptoms of ischemia without obstructive CAD, absence of CMD, and preserved LVEF, isolated elevated LVEDP is associated with a significantly higher systolic and diastolic blood pressure, higher LV mass-to-volume ratio and lower LV EDVI. These results suggest these women have maladaptive remodeling to blood pressure. Given the relatively high prevalence of HFpEF in women, these hypothesis-generating results suggest that further study of ventricular remodeling is warranted.

Fitness in Young Adulthood and Long-Term Cardiac Structure and Function: The CARDIA Study

OBJECTIVES

This study sought to evaluate the association between early-life cardiorespiratory fitness (CRF) and measures of left ventricular (LV) structure and function in midlife.

BACKGROUND

Low CRF in midlife is associated with a higher risk of heart failure. However, the unique contributions of early-life CRF toward measures of LV structure and function in middle age are not known.

METHODS

CARDIA (Coronary Artery Risk Development in Young Adults) study participants with a baseline maximal treadmill test and an echocardiogram at year 25 were included. Associations among baseline CRF, CRF change, and echocardiographic LV parameters (global longitudinal strain [GLS] and global circumferential strain, E/e') were assessed using multivariable linear regression.

RESULTS

The study included 3,433 participants. After adjustment for baseline demographic and clinical characteristics, lower baseline CRF was significantly associated with higher LV strain (standardized parameter estimate [Std β] = -0.06; p = 0.03 for GLS) and ratio of early transmitral flow velocity to early peak diastolic mitral annular velocity (E/e') (Std β = -0.10; p = 0.0001 for lateral E/e'), findings suggesting impaired contractility and elevated diastolic filling pressure in midlife. After additional adjustment for cumulative cardiovascular risk factor burden observed over the follow-up period, the association of CRF with LV strain attenuated substantially (p = 0.36), whereas the association with diastolic filling pressure remained significant (Std β = -0.05; p = 0.02 for lateral E/e'). In a subgroup of participants with repeat CRF tests at year 20, greater decline in CRF was significantly associated with increased abnormalities in GLS (Std β = -0.05; p = 0.02) and higher diastolic filling pressure (Std β = -0.06; p = 0.006 for lateral E/e') in middle age.

CONCLUSIONS

CRF in young adulthood and CRF change were associated with measures of LV systolic function and diastolic filling pressure in middle age. Low CRF-associated abnormalities in systolic function were related to the associated higher cardiovascular risk factor burden. In contrast, the inverse association between CRF and LV diastolic filling pressure was independent of cardiovascular risk factor burden.

Relationship among LRP1 expression, Pyk2 phosphorylation and MMP-9 activation in left ventricular remodelling after myocardial infarction

Left ventricular (LV) remodelling after myocardial infarction (MI) is a crucial determinant of the clinical course of heart failure. Matrix metalloproteinase (MMP) activation is strongly associated with LV remodelling after MI. Elucidation of plasma membrane receptors related to the activation of specific MMPs is fundamental for treating adverse cardiac remodelling after MI. The aim of current investigation was to explore the potential association between the low‐density lipoprotein receptor‐related protein 1 (LRP1) and MMP‐9 and MMP‐2 spatiotemporal expression after MI. Real‐time PCR and Western blot analyses showed that LRP1 mRNA and protein expression levels, respectively, were significantly increased in peri‐infarct and infarct zones at 10 and 21 days after MI. Confocal microscopy demonstrated high colocalization between LRP1 and the fibroblast marker vimentin, indicating that LRP1 is mostly expressed by cardiac fibroblasts in peri‐infarct and infarct areas. LRP1 also colocalized with proline‐rich tyrosine kinase 2 (pPyk2) and MMP‐9 in cardiac fibroblasts in ischaemic areas at 10 and 21 days after MI. Cell culture experiments revealed that hypoxia increases LRP1, pPyk2 protein levels and MMP‐9 activity in fibroblasts, without significant changes in MMP‐2 activity. MMP‐9 activation by hypoxia requires LRP1 and Pyk2 phosphorylation in fibroblasts. Collectively, our in vivo and in vitro data support a major role of cardiac fibroblast LRP1 levels on MMP‐9 up‐regulation associated with ventricular remodelling after MI.

Diastolic dysfunction in hypertension

Hypertension and coronary heart disease, often coexisting, are the most common risk factors for heart failure. The progression of hypertensive heart disease involves myocardial fibrosis and alterations in the left ventricular geometry that precede the functional change, initially asymptomatic. The left ventricular diastolic dysfunction is part of this continuum being defined by the presence of left ventricular diastolic dysfunction without signs or symptoms of heart failure or poor left ventricular systolic function. It is highly prevalent in hypertensive patients and is associated with increased cardiovascular morbidity and mortality. Despite its growing importance in clinical practice it remains poorly understood. This review aims to present the epidemiological fundamentals and the latest developments in the pathophysiology, diagnosis and treatment of left ventricular diastolic dysfunction.

Conformational and thermal characterization of left ventricle remodeling post-myocardial infarction

Adverse cardiac remodeling after myocardial infarction (MI) causes impaired ventricular function and heart failure. Histopathological characterization is commonly used to detect the location, size and shape of MI sites. However, the information about chemical composition, physical structure and molecular mobility of peri- and infarct zones post-MI is rather limited. The main objective of this work was to explore the spatiotemporal biochemical and biophysical alterations of key cardiac components post-MI. The FTIR spectra of healthy and remote myocardial tissue shows amides A, I, II and III associated with proteins in freeze-died tissue as major absorptions bands. In infarcted myocardium, the spectrum of these main absorptions was deeply altered. FITR evidenced an increase of the amide A band and the distinct feature of the collagen specific absorption band at 1338cm^-1 in the infarct area at 21days post-MI. At 21days post-MI, it also appears an important shift of amide I from 1646cm^-1 to 1637cm^-1 that suggests the predominance of the triple helical conformation in the proteins. The new spectra bands also indicate an increase in proteoglycans, residues of carbohydrates in proteins and polysaccharides in ischemic areas. Thermal analysis indicates a deep increase of unfreezable water/freezable water in peri- and infarcted tissues. In infarcted tissue is evidenced the impairment of myofibrillar proteins thermal profile and the emergence of a new structure. In conclusion, our results indicate a profound evolution of protein secondary structures in association with collagen deposition and reorganization of water involved in the scar maturation of peri- and infarct zones post-MI.

Myocardial hypertrophy and its role in heart failure with preserved ejection fraction

Left ventricular hypertrophy (LVH) is the most common myocardial structural abnormality associated with heart failure with preserved ejection fraction (HFpEF). LVH is driven by neurohumoral activation, increased mechanical load, and cytokines associated with arterial hypertension, chronic kidney disease, diabetes, and other comorbidities. Here we discuss the experimental and clinical evidence that links LVH to diastolic dysfunction and qualifies LVH as one diagnostic marker for HFpEF. Mechanisms leading to diastolic dysfunction in LVH are incompletely understood, but may include extracellular matrix changes, vascular dysfunction, as well as altered cardiomyocyte mechano-elastical properties. Beating cardiomyocytes from HFpEF patients have not yet been studied, but we and others have shown increased Ca(2+) turnover and impaired relaxation in cardiomyocytes from hypertrophied hearts. Structural myocardial remodeling can lead to heterogeneity in regional myocardial contractile function, which contributes to diastolic dysfunction in HFpEF. In the clinical setting of patients with compound comorbidities, diastolic dysfunction may occur independently of LVH. This may be one explanation why current approaches to reduce LVH have not been effective to improve symptoms and prognosis in HFpEF. Exercise training, on the other hand, in clinical trials improved exercise tolerance and diastolic function, but did not reduce LVH. Thus current clinical evidence does not support regression of LVH as a surrogate marker for (short-term) improvement of HFpEF.

Association of cardiorespiratory fitness with left ventricular remodeling and diastolic function: the Cooper Center Longitudinal Study

OBJECTIVES

This study sought to compare the cross-sectional associations between fitness and echocardiographic measures of cardiac structure and function.

BACKGROUND

Cardiorespiratory fitness is inversely associated with heart failure risk. However, the mechanism through which fitness lowers heart failure risk is not fully understood.

METHODS

We included 1,678 men and 1,247 women from the Cooper Center Longitudinal Study who received an echocardiogram from 1999 to 2011. Fitness was estimated by Balke protocol (in metabolic equivalents) and also categorized into age-specific quartiles, with quartile 1 representing low fitness. Cross-sectional associations between fitness (in metabolic equivalents) and relative wall thickness, left ventricular end-diastolic diameter indexed to body surface area, left atrial volume indexed to body surface area, left ventricular systolic function, and E/e' ratio were determined using multivariable linear regression analysis.

RESULTS

Higher levels of mid-life fitness (metabolic equivalents) were associated with larger indexed left atrial volume (men: beta = 0.769, p < 0.0001; women: beta = 0.879, p value ≤0.0001) and indexed left ventricular end-diastolic diameter (men: beta = 0.231, p < 0.001; women: beta = 0.264, p < 0.0001). Similarly, a higher level of fitness was associated with a smaller relative wall thickness (men: beta = -0.002, p = 0.04; women: beta = -0.005, p < 0.0001) and E/e' ratio (men: beta = -0.11, p = 0.003; women: beta = -0.13, p = 0.01). However, there was no association between low fitness and left ventricular systolic function (p = NS).

CONCLUSIONS

Low fitness is associated with a higher prevalence of concentric remodeling and diastolic dysfunction, suggesting that exercise may lower heart failure risk through its effect on favorable cardiac remodeling and improved diastolic function.

Diagnosis and management of pulmonary hypertension associated with left ventricular diastolic dysfunction

Pulmonary hypertension (PH) is commonly seen in patients who present with left ventricular diastolic dysfunction (LVDD) and is considered a marker of poor prognosis. While PH in this setting is thought to result from pulmonary venous congestion, there is a subset of patients in which pulmonary pressures fail to improve with appropriate management of diastolic heart failure and go on to develop a clinical picture similar to that of patients with pulmonary arterial hypertension (PAH). Despite the utility of Doppler echocardiography and exercise testing in the initial evaluation of patients with suspected PH-LVDD, the diagnosis can only be confirmed using right heart catheterization. Management of PH-LVDD centers on both optimizing fluid management and afterload reduction to reducing left ventricular diastolic pressures and also increase pulmonary venous return. To date, there is no clear evidence that addition of PH-specific drugs can improve clinical outcomes, and their use should only be considered in the setting of clinical trials. In conclusion, PH-LVDD remains a challenging clinical entity that complicates the management of left ventricular dysfunction and significantly contributes to its morbidity and mortality. Determination of the optimal diagnostic and treatment strategies for this form of PH should be the goal of future studies.

Abnormal early diastolic intraventricular flow 'kinetic energy index' assessed by vector flow mapping in patients with elevated filling pressure

AIMS

Recently developed vector flow mapping (VFM) enables evaluation of local flow dynamics without angle dependency. This study used VFM to evaluate quantitatively the index of intraventricular haemodynamic kinetic energy in patients with left ventricular (LV) diastolic dysfunction and to compare those with normal subjects.

METHODS AND RESULTS

We studied 25 patients with estimated high left atrial (LA) pressure (pseudonormal: PN group) and 36 normal subjects (control group). Left ventricle was divided into basal, mid, and apical segments. Intraventricular haemodynamic energy was evaluated in the dimension of speed, and it was defined as the kinetic energy index. We calculated this index and created time-energy index curves. The time interval from electrocardiogram (ECG) R wave to peak index was measured, and time differences of the peak index between basal and other segments were defined as ΔT-mid and ΔT-apex. In both groups, early diastolic peak kinetic energy index in mid and apical segments was significantly lower than that in the basal segment. Time to peak index did not differ in apex, mid, and basal segments in the control group but was significantly longer in the apex than that in the basal segment in the PN group. ΔT-mid and ΔT-apex were significantly larger in the PN group than the control group. Multiple regression analysis showed sphericity index, E/E' to be significant independent variables determining ΔT apex.

CONCLUSION

Retarded apical kinetic energy fluid dynamics were detected using VFM and were closely associated with LV spherical remodelling in patients with high LA pressure.

Association of myocardial fibrosis, B-type natriuretic peptide, and cardiac magnetic resonance parameters of remodeling in chronic ischemic cardiomyopathy

The left ventricular (LV) scar size detected by cardiac magnetic resonance (CMR) imaging in ischemic cardiomyopathy (IC) has been correlated with mortality. However, the associations among myocardial fibrosis, ventricular geometry, and physiologic measures of myocardial performance remain to be defined. A retrospective analysis of patients with stable chronic IC (LV ejection fraction ≤50%) who underwent CMR imaging from 2004 to 2010 and had plasma B-type natriuretic peptide (BNP) measured within 14 days of the CMR study was undertaken. A total of 38 patients met the criteria (mean age 66 ± 10 years; 31 men [82%]). The duration of IC was 67 ± 69 months. The CMR characteristics included LV dilation (LV end-diastolic dimension 62 ± 8 mm) and severe systolic dysfunction (LV ejection fraction 28 ± 11%). The average quantitated myocardial fibrosis was 20 ± 12% of the LV mass. When stratified by fibrotic mass, increased myocardial scar size was associated with increased LV cavity size (p = 0.007), lower LV ejection fraction (p = 0.04), and higher BNP (p = 0.013). In comparison, when stratified by median BNP (475 pg/ml), an elevated BNP level was associated, not only with LV size, function, and degree of fibrosis, but also with increased meridional wall stress (p = 0.002) and worse New York Heart Association functional class (p = 0.006). In conclusion, in chronic IC, quantitated myocardial fibrosis is associated with CMR structural and functional LV abnormalities. Elevated BNP levels are related to high-risk structural and functional CMR abnormalities and wall stress and functional status. Myocardial fibrosis appears to be related to plasma BNP through the processes of ventricular remodeling.

Recent advances in stress echocardiography

PURPOSE OF REVIEW

This article reviews the recent advances in stress echocardiography, with particular attention to articles published in 2010 and 2011. It summarizes the developments in the diagnostic and prognostic capabilities of stress echocardiography, discusses new data regarding the safety of stress echocardiography, and highlights emerging roles for stress echocardiography in the areas of left ventricular assist devices, cardiac transplantation, strain-rate echocardiography, and myocardial perfusion imaging.

RECENT FINDINGS

Stress echocardiography represents a well validated tool in the diagnosis and assessment of patients with known or suspected coronary artery disease. Recently, data have emerged supporting the prognostic capabilities of stress echocardiography in patients with various levels of systolic dysfunction, diastolic abnormalities, and valvular heart disease. New studies continue to document the safety of stress echocardiography, particularly with regard to arrhythmias, neuropsychiatric symptoms, dosing of dobutamine, and intravenous contrast. Studies are now suggesting that stress echocardiography may play novel roles in the evaluation of patients with left ventricular assist devices or potential donors for cardiac transplantation. Technologic developments in myocardial contrast perfusion imaging, three-dimensional imaging, and strain-rate echocardiography will continue to advance the field.

SUMMARY

Stress echocardiography represents a dynamic, versatile, and well validated tool for the noninvasive assessment of patients with a wide spectrum of cardiovascular diseases.

Myocardial remodeling: cellular and extracellular events and targets

The focus of this review is on translational studies utilizing large-animal models and clinical studies that provide fundamental insight into cellular and extracellular pathways contributing to post-myocardial infarction (MI) left ventricle (LV) remodeling. Specifically, both large-animal and clinical studies have examined the potential role of endogenous and exogenous stem cells to alter the course of LV remodeling. Interestingly, there have been alterations in LV remodeling with stem cell treatment despite a lack of long-term cell engraftment. The translation of the full potential of stem cell treatments to clinical studies has yet to be realized. The modulation of proteolytic pathways that contribute to the post-MI remodeling process has also been examined. On the basis of recent large-animal studies, there appears to be a relationship between stem cell treatment post-MI and the modification of proteolytic pathways, generating the hypothesis that stem cells leave an echo effect that moderates LV remodeling.

Cardiac allograft hypertrophy is associated with impaired exercise tolerance after heart transplantation

BACKGROUND

Exercise performance, an important aspect of quality of life, remains limited after heart transplantation (HTx). This study examines the effect of cardiac allograft remodeling on functional capacity after HTx.

METHODS

The total cohort of 117 HTx recipients, based on echocardiographic determination of left ventricle mass and relative wall thickness at 1 year after HTx, was divided into 3 groups: (1) NG, normal geometry; (2) CR, concentric remodeling; and (3) CH, concentric hypertrophy. Cardiopulmonary exercise testing was performed 5.03 ± 3.08 years after HTx in all patients. Patients with acute rejection or significant graft vasculopathy were excluded.

RESULTS

At 1 year post-HTx, 30% of patients had CH, 55% had CR and 15% had NG. Exercise tolerance, measured by maximum achieved metabolic equivalents (4.62 ± 1.44 vs 5.52 ± 0.96 kcal/kg/h), normalized peak Vo(2) (52 ± 14% vs 63 ± 12%) and Ve/Vco(2) (41 ± 17 vs 34 ± 6), was impaired in the CH group compared with the NG group. A peak Vo(2) ≤14 ml/kg/min was found in 6%, 22% and 48% of patients in the NG, CR and CH groups, respectively (p = 0.01). The CH pattern was associated with a 7.4-fold increase in relative risk for a peak Vo(2) ≤14 ml/kg/min compared with NG patients (95% confidence interval 1.1 to 51.9, p = 0.001). After multivariate analysis, a 1-year CH pattern was independently associated with a reduced normalized peak Vo(2) (p = 0.018) and an elevated Ve/Vco(2) (p = 0.035).

CONCLUSIONS

The presence of CH at 1 year after HTx is independently associated with decreased normalized peak Vo(2) and increased ventilatory response in stable heart transplant recipients. The identification of CH, a potentially reversible mechanism of impairment in exercise capacity after HTx, may have major clinical implications.

Impaired exercise tolerance is associated with increased urine albumin excretion in the early stages of essential hypertension

BACKGROUND

Our aim was to investigate the relationship between impaired exercise capacity and albumin excretion level in the setting of never treated essential hypertension.

DESIGN AND METHODS

For this purpose, 338 consecutive essential hypertensives (52 ± 8.5 years, 227 males, office BP = 148.6/96.1 mmHg) performed a negative for myocardial ischemia, maximal treadmill exercise testing and were classified based on the gender specific median value of the amount of metabolic equivalents (METs) achieved (10.1 ml/kg/min for women and 11 ml/kg/min for men) as fit (n = 177) and unfit (n = 161). All the participants underwent 24-h ambulatory BP monitoring, complete echocardiographic study including left ventricular diastolic function evaluation and determination of albumin to creatinine ratio (ACR) on two non-consecutive morning spot urine samples.

RESULTS

Unfit hypertensives compared to the fit ones were older by 4.5 years (p < 0.001) and had greater waist circumference by 4.5 cm (p < 0.001), body mass index by 1.3 kg/m(2) (p = 0.001), 24-h pulse pressure by 3.0 mmHg (p = 0.005), ACR levels by 12.6% (p = 0.003) and prevalence of microalbuminuria (19.5% vs 10.3%, p = 0.007) while the differences in diastolic function indices lost significance after adjustment for confounders. By applying stepwise multivariate linear regression analysis in order to identify the predictors of METs, it was revealed that age (β = -0.338, p = 0.045), gender (β = 0.274, p = 0.045), body mass index (β = -0.230, p = 0.045) and logACR (β = -0.151, p = 0.004) were the only independent predictors of exercise capacity.

CONCLUSIONS

Increased ACR is associated with diminished exercise capacity in the early stages of essential hypertension independently from adverse cardiac adaptations, further elucidating the adverse prognostic role of albuminuria in this setting.

Heart failure with preserved left ventricular ejection fraction: concepts, misconceptions and future directions

Heart failure with preserved left ventricular ejection fraction (HFPEF) represents a huge medical problem, especially in light of an increasing elderly population. Dysfunction of both left ventricular filling and ejection, combined with adverse loading conditions related to advanced age, arterial hypertension, diabetes mellitus, obesity and atrial fibrillation are fundamental pathophysiological mechanisms. Hypertension is probably the most important modifiable risk factor. The diagnosis has largely been based on signs of increased left ventricular filling pressure. Additional matters of debate are the interpretation of left ventricular ejection fraction in concentric remodelling and the cut-off used for the definition of HFPEF, as well as inconsistencies related to prevalence and prognosis, and lack of benefit of drugs in randomized trials.