Determination of left ventricular chamber stiffness from the time for deceleration of early left ventricular filling

Deriving phenotype-representative left ventricular flow patterns by reduced-order modeling and classification

BACKGROUND

Extracting phenotype-representative flow patterns and their associated numerical metrics is a bottleneck in the clinical translation of advanced cardiac flow imaging modalities. We hypothesized that reduced-order models (ROMs) are a suitable strategy for deriving simple and interpretable clinical metrics of intraventricular flow suitable for further assessments. Combined with machine learning (ML) flow-based ROMs could provide new insight to help diagnose and risk-stratify patients.

METHODS

We analyzed 2D color-Doppler echocardiograms of 81 non-ischemic dilated cardiomyopathy (DCM) patients, 51 hypertrophic cardiomyopathy (HCM) patients, and 77 normal volunteers (Control). We applied proper orthogonal decomposition (POD) to build patient-specific and cohort-specific ROMs of LV flow. Each ROM aggregates a low number of components representing a spatially dependent velocity map modulated along the cardiac cycle by a time-dependent coefficient. We tested three classifiers using deliberately simple ML analyses of these ROMs with varying supervision levels. In supervised models, hyperparameter grid search was used to derive the ROMs that maximize classification power. The classifiers were blinded to LV chamber geometry and function. We ran vector flow mapping on the color-Doppler sequences to help visualize flow patterns and interpret the ML results.

RESULTS

POD-based ROMs stably represented each cohort through 10-fold cross-validation. The principal POD mode captured >80 % of the flow kinetic energy (KE) in all cohorts and represented the LV filling/emptying jets. Mode 2 represented the diastolic vortex and its KE contribution ranged from <1 % (HCM) to 13 % (DCM). Semi-unsupervised classification using patient-specific ROMs revealed that the KE ratio of these two principal modes, the vortex-to-jet (V2J) energy ratio, is a simple, interpretable metric that discriminates DCM, HCM, and Control patients. Receiver operating characteristic curves using V2J as classifier had areas under the curve of 0.81, 0.91, and 0.95 for distinguishing HCM vs. Control, DCM vs. Control, and DCM vs. HCM, respectively.

CONCLUSIONS

Modal decomposition of cardiac flow can be used to create ROMs of normal and pathological flow patterns, uncovering simple interpretable flow metrics with power to discriminate disease states, and particularly suitable for further processing using ML.

Deriving Explainable Metrics of Left Ventricular Flow by Reduced-Order Modeling and Classification

Background

Extracting explainable flow metrics is a bottleneck to the clinical translation of advanced cardiac flow imaging modalities. We hypothesized that reduced-order models (ROMs) of intraventricular flow are a suitable strategy for deriving simple and interpretable clinical metrics suitable for further assessments. Combined with machine learning (ML) flow-based ROMs could provide new insight to help diagnose and risk-stratify patients.

Methods

We analyzed 2D color-Doppler echocardiograms of 81 non-ischemic dilated cardiomyopathy (DCM) patients, 51 hypertrophic cardiomyopathy (HCM) patients, and 77 normal volunteers (Control). We applied proper orthogonal decomposition (POD) to build patient-specific and cohort-specific ROMs of LV flow. Each ROM aggregates a low number of components representing a spatially dependent velocity map modulated along the cardiac cycle by a time-dependent coefficient. We tested three classifiers using deliberately simple ML analyses of these ROMs with varying supervision levels. In supervised models, hyperparameter gridsearch was used to derive the ROMs that maximize classification power. The classifiers were blinded to LV chamber geometry and function. We ran vector flow mapping on the color-Doppler sequences to help visualize flow patterns and interpret the ML results.

Results

POD-based ROMs stably represented each cohort through 10-fold cross-validation. The principal POD mode captured >80% of the flow kinetic energy (KE) in all cohorts and represented the LV filling/emptying jets. Mode 2 represented the diastolic vortex and its KE contribution ranged from <1% (HCM) to 13% (DCM). Semi-unsupervised classification using patient-specific ROMs revealed that the KE ratio of these two principal modes, the vortex-to-jet (V2J) energy ratio, is a simple, interpretable metric that discriminates DCM, HCM, and Control patients. Receiver operating characteristic curves using V2J as classifier had areas under the curve of 0.81, 0.91, and 0.95 for distinguishing HCM vs. Control, DCM vs. Control, and DCM vs. HCM, respectively.

Conclusions

Modal decomposition of cardiac flow can be used to create ROMs of normal and pathological flow patterns, uncovering simple interpretable flow metrics with power to discriminate disease states, and particularly suitable for further processing using ML.

Left Atrial Filling Time Index (LAFTI) Evaluated by 2D Speckle Tracking Echocardiography Predicts Poor Cardiac Prognosis in Patients with Heart Failure

Left atrial (LA) dysfunction is known to be a more sensitive prognostic marker than left ventricular (LV) dysfunction in patients with heart failure (HF). Persistent LA overload increases LA stiffness which impairs LA relaxation. The aim of this study was to investigate whether LA filling time is associated with clinical outcomes in patients with HF. Two-dimensional speckle tracking echocardiography (2DSTE) was performed at discharge, to measure LA and LV strain in 179 HF patients admitted to our hospital. The LA filling time index (LAFTI) was defined as the time from onset of the R wave to the peak LA systolic strain divided by the R-R interval. All patients were prospectively followed with cardiac events including cardiac death and rehospitalization for HF. There were 64 cardiac events during a median follow-up period of 451 days. There were no significant differences in heart rate, severity of HF at discharge, etiology of HF, severity of mitral regurgitation, or LV global longitudinal strain between the cardiac event group and no cardiac event group. Patients with cardiac events had significantly higher levels of brain natriuretic peptide (BNP), ratio of the E wave to e' (E/e'), left atrial volume index (LAVI), and lower LAFTI than those without. Kaplan-Meier analysis showed that patients with lower LAFTI were associated with higher cardiac event rates. Multivariate Cox hazard analysis showed that LAFTI was independently associated with the cardiac events after adjustment for confounding factors. In conclusion, LAFTI is a feasible predictor for cardiac events in patients with HF.

Early Impairment of Right Ventricular Morphology and Function in Transthyretin-Related Cardiac Amyloidosis

Background:

Our study aimed to evaluate right ventricular (RV) morphology and strain (S) in the early stage of familial transthyretin (TTR) cardiac amyloidosis (CA).

Methods and Results:

Thirty-seven patients with transthyretin mutation underwent ^99mTc-3,3-diphosphono-1,2 propanodicarboxylic acid (^99mTc-DPD) scans and/or cardiac magnetic resonance (CMR) to identify TTR CA. Each patient underwent echocardiography to quantify RV dimensions, tricuspid annular plane systolic excursion (TAPSE), systolic pulmonary artery pressure (sPAP), longitudinal (L) strain of the RV free wall, left ventricular (LV) septal thickness (ST), ejection fraction, E/E', LV global (G) L, radial (R), and circumferential (C) S. ^99mTc-DPD and CMR revealed the accumulation in 22 of 37 patients (CA group) and no accumulation in 15 patients (no-CA group). Left ventricular (LV) septal thickness (ST) was higher (P < 0.0001) while LV ejection fraction and E/E' were lower (P < 0.05) in the CA group than the no-CA group. LV-global longitudinal strain (LS) was lower (P < 0.0001) in the CA-group than the no CA-group, whereas LV-global circumferential strain and LV-global radial strain were similar. The CA group showed higher values of RV dimensions (P < 0.05) and sPAP (0.02) and a lower (P = 0.002) TAPSE. Globally, RV-LS was lower (P = 0.005) in the CA group than the no-CA group. Basal and mid segments of the RV free wall showed a lower LS in the CA group than the no-CA group (P < 0.01), while apical S was similar between groups.

Conclusions:

RV deformation, particularly in basal and mid segments, is early impaired in CA.

Effects of Eplerenone on Blood Pressure and Echocardiographic and Serum Biochemical Variables in Five Healthy Dogs: A Pilot Study

Eplerenone (EP), an aldosterone antagonist, is reported to produce renal and cardiac protective effects in noncanine species. However, there are no detailed reports available on cardiovascular effects of EP in dogs. This study aimed to determine effect of EP on echocardiographic parameters, blood pressures, and biochemical variables in healthy dogs. Five healthy Beagle dogs were randomly divided and repeatedly used in each of 3 dose groups, receiving 2.5, 5, or 10 mg/kg BW EP orally q24 h for 4 wks. Serum biochemical test, blood pressure, and Doppler echocardiography measurements were performed before EP administration and at 1, 2, and 4 weeks after EP administration. Treatment with EP reduced mean blood pressure in a dose-dependent manner and significantly (but in a dose-independent manner) decreased left atrium/aorta ratio, early diastolic transmitral flow, early diastolic transmitral flow/late diastolic transmitral flow, peak velocity of early diastolic transmitral flow/peak velocity of early diastolic mitral annular motion, left ventricle and right ventricle Tei indices, stroke volume, cardiac output, and mid systole myocardial velocity gradient 1 to 4 weeks after administration. Deceleration time of early diastolic transmitral flow significantly increased after EP administration. No significant changes were observed in serum biochemical variables. The results indicated that EP might reduce preload, thereby decreasing left atrial size. In addition, reduction of left ventricular stiffness may have theoretically taken place but this could not be tested using the present study design. It is suggested that EP administration within the dose range used in this study is safe for administration to healthy dogs. Further studies are needed to explore both safety and efficacy, as well as to seek a recommended dose range of EP treatment in client-owned dogs with heart disease.

Severe heart failure (NYHA Class IV) is associated with increased left ventricular mass index and short mitral deceleration time in severe aortic valve stenosis

BACKGROUND

In aortic valve stenosis (AS), congestive heart failure (CHF) is a well-established symptom that indicates the need for surgical aortic valve replacement (SAVR). However, it is difficult to judge whether CHF symptoms such as dyspnea are caused by severe AS or other conditions, especially in elderly persons with restricted mobility or other organ complications. It is important to identify objective and noninvasive parameters associated with severe CHF symptoms in severe AS.

METHODS

One hundred ninety-eight patients with severe AS without left ventricular (LV) dysfunction were retrospectively studied. CHF symptoms were classified by New York Heart Association (NYHA) functional class. Echo parameters were compared between NYHA I-III and NYHA IV.

RESULTS

Patients with NYHA IV (n = 40; 20%) were older (86 ± 6 vs 82 ± 8 years; P = .001) and had a larger LV mass index (LVMI) (157 ± 43 vs 114 ± 34 g/m² , P < .001), a higher transmitral flow velocity ratio (E/A) (1.31 ± 0.62 vs 0.93 ± 0.42; P = .001), a shorter deceleration time (DT) (202 ± 72 vs 286 ± 98 ms; P < .001), and a higher systolic pulmonary arterial pressure (SPAP) (44 ± 13 vs 35 ± 13 mm Hg; P < .001) than patients with NYHA I-III. On multivariable analysis, LVMI and DT were independently associated with NYHA IV. Receiver operating characteristic curve analysis identified LVMI ≥ 142 g/m² and DT ≤ 194 ms as the cutoff values associated with NYHA IV in patients with severe AS.

CONCLUSION

Left ventricular mass index and DT were independently associated with severe heart failure (NYHA IV). These echo parameters could be helpful to judge whether CHF symptoms are caused by severe AS.

Left atrial dilatation in systolic heart failure: a marker of poor prognosis, not just a buffer between the left ventricle and pulmonary circulation

BACKGROUND

The relation between systolic pulmonary pressure (sPAP) and left atrium in patients with heart failure (HF) is unclear. Diastolic dysfunction, expressed as restrictive mitral filling pattern (RMP), and functional mitral regurgitation (FMR) are associated with both LA enlargement and increased sPAP. We aimed to evaluate whether atrial dilation might modulate the consequences of RMP and FMR on the pulmonary circulation of patients with HF with reduced ejection fraction (HFrEF).

METHODS

1256 HFrEF patients were retrospectively recruited in four Italian centers. Left ventricular (LVD) and atrial (LAD) diameters were measure by m-mode, and EF were measured. RMP was defined as E-wave deceleration time lower than 140 ms. FMR was quantitatively measured. sPAP was evaluated based on maximal tricuspid regurgitant velocity and estimated right atrial pressure.

RESULTS

Final study population was formed by 1005 patients because of unavailability of sPAP in 252 patients. Mean EF was 33 ± 3, 35% had RMP, 67% had mild, and 26% moderate-to-severe FMR. 69% of patients had increased sPAP. A significant association was observed between sPAP and EF, RMP, FMR, and LAD (p < 0.0001 for all). At multivariate analysis, LAD was positively associated with sPAP (p < 0.0001) independently of EF, RMP, and FMR. Analogously, LAD (p < 0.05) was associated with more severe symptoms and worse prognosis after adjustment for LV function and FMR.

CONCLUSION

LA dilation was positively associated with sPAP independently of EF, RMP, and FMR. This highlights that LA size should be considered a marker of the severity of the disease.

Is universal grading of diastolic function by echocardiography feasible?

Quantitation of diastolic function centers on the assessment of active and passive ventricular properties, and involves measurement estimates of ventricular relaxation, and chamber and myocardial stiffness. Diastolic dysfunction is a propensity to develop increased left ventricular (LV) end-diastolic pressure. Recently American Society of Echocardiography and European Association of Cardiovascular Imaging (ASE/EACVI) proposed a new grading system. While the new guidelines are ambiguous and with cutoff points that may misclassify patients as both sicker and healthier than they are. This article outlines the pathophysiology behind the diastolic dysfunction and role and limitation of echocardiographic assessment in predicting LV diastolic dysfunction.

Impact of left ventricular filling parameters on outcome of patients undergoing trans-catheter aortic valve replacement

Aim

To assess the impact of left ventricular (LV) filling parameters on outcomes following trans-catheter aortic valve replacement (TAVR).

Methods and results

A total of 526 TAVR patients were compared with 300 patients with severe aortic stenosis (AS) treated conservatively. Clinical variables were collected along with echocardiographic data at baseline, 1 month, and 6 months after study entry. End points included all-cause mortality and the combination of death and heart failure admission. LV filling parameters associated with mortality included reduced A wave velocity (P = 0.005) and shorter deceleration time (DT) (P = 0.0005). DT was superior to all other parameters (P = 0.05) apart from patients with atrial fibrillation in whom E/e' was better. Short DT (<160 ms) was associated with lower survival than long DT (≥220 ms; P = 0.002) or intermediate DT (P = 0.05), even after adjustment for age, gender, stroke volume index (SVI), and co-morbidities. However, patients with short baseline DT exhibited greater improvement in DT, E/A, and systolic pulmonary pressure at follow-up than patients with baseline DT ≥160 ms (P < 0.05 for all time x group interactions). Most importantly, among patients with short DT, TAVR was associated with better survival than conservative treatment (46 ± 7 vs. 28 ± 12% at 3 years, P = 0.05), even after adjustment for age, gender, and SVI (P = 0.05).

Conclusion

Short DT is an independent predictor of adverse outcome following TAVR. Nevertheless, LV filling parameters improve in most patients post TAVR, and TAVR is associated with improved survival compared with conservative therapy, even in patients with evidence of elevated LV filling. Thus, evidence of elevated LV filling should not be viewed as a contraindication for TAVR.

Prolonged QRS duration on surface electrocardiogram is associated with left ventricular restrictive filling pattern

Background

Prolonged QRS duration is associated with decreased left ventricular (LV) systolic function. However, the relation between LV restrictive filling pattern (RFP) and QRS duration has not been investigated yet. The purpose of our study was to assess this relationship.

Methods

We analyzed standard 12-lead surface electrocardiogram (ECG) of 155 consecutive patients. Mitral inflow and septal tissue velocities were obtained using the apical 4-chamber view with pulsed Doppler echocardiography. Patients were divided into 2 groups according to measured deceleration time (DT): restrictive (with DT ≤130 ms) or non-restrictive (with DT >130 ms).

Results

QRS duration was significantly longer in the restrictive group than in the non-restrictive group (0.101 vs. 0.090 s, p < 0.0001). QRS duration of >0.10 s was highly specific (82.6%), but modestly sensitive (64.7%), for the prediction of LV RFP. Multivariate analyses demonstrated that E/A ratio, peak E, peak A, septal e’, and a’ velocities were significantly associated with RFP.

Conclusions

Prolonged QRS duration (>0.10 s) obtained from a standard resting 12-lead ECG is associated with LV RFP. However, the relationship of QRS duration with RFP was not independent of echocardiographic parameters.

The link between exercise and titin passive stiffness

NEW FINDINGS

What is the topic of this review? This review focuses on how in vivo and molecular measurements of cardiac passive stiffness can predict exercise tolerance and how exercise training can reduce cardiac passive stiffness. What advances does it highlight? This review highlights advances in understanding the relationship between molecular (titin-based) and in vivo (left ventricular) passive stiffness, how passive stiffness modifies exercise tolerance, and how exercise training may be therapeutic for cardiac diseases with increased passive stiffness. Exercise can help alleviate the negative effects of cardiovascular disease and cardiovascular co-morbidities associated with sedentary behaviour; this may be especially true in diseases that are associated with increased left ventricular passive stiffness. In this review, we discuss the inverse relationship between exercise tolerance and cardiac passive stiffness. Passive stiffness is the physical property of cardiac muscle to produce a resistive force when stretched, which, in vivo, is measured using the left ventricular end diastolic pressure-volume relationship or is estimated using echocardiography. The giant elastic protein titin is the major contributor to passive stiffness at physiological muscle (sarcomere) lengths. Passive stiffness can be modified by altering titin isoform size or by post-translational modifications. In both human and animal models, increased left ventricular passive stiffness is associated with reduced exercise tolerance due to impaired diastolic filling, suggesting that increased passive stiffness predicts reduced exercise tolerance. At the same time, exercise training itself may induce both short- and long-term changes in titin-based passive stiffness, suggesting that exercise may be a treatment for diseases associated with increased passive stiffness. Direct modification of passive stiffness to improve exercise tolerance is a potential therapeutic approach. Titin passive stiffness itself may be a treatment target based on the recent discovery of RNA binding motif 20, which modifies titin isoform size and passive stiffness. Translating these discoveries that link exercise and left ventricular passive stiffness may provide new methods to enhance exercise tolerance and treat patients with cardiovascular disease.

A Test in Context: E/A and E/e' to Assess Diastolic Dysfunction and LV Filling Pressure

Diastolic dysfunction represents a combination of impaired left ventricular (LV) relaxation, restoration forces, myocyte lengthening load, and atrial function, culminating in increased LV filling pressures. Current Doppler echocardiography guidelines recommend using early to late diastolic transmitral flow velocity (E/A) to assess diastolic function, and E to early diastolic mitral annular tissue velocity (E/e') to estimate LV filling pressures. Although both parameters have important diagnostic and prognostic implications, they should be interpreted in the context of a patient's age and the rest of the echocardiogram to describe diastolic function and guide patient management. This review discusses: 1) the physiological basis for the E/A and E/e' ratios; 2) their roles in diagnosing diastolic dysfunction; 3) prognostic implications of abnormalities in E/A and E/e'; 4) special scenarios of the E/A and E/e' ratios that are either useful or challenging when evaluating diastolic function clinically; and 5) their usefulness in guiding therapeutic decision making.

Reliability of updated left ventricular diastolic function recommendations in predicting elevated left ventricular filling pressure and prognosis

An updated 2016 echocardiographic algorithm for diagnosing left ventricular (LV) diastolic dysfunction (DD) was recently proposed. We aimed to assess the reliability of the 2016 echocardiographic LVDD grading algorithm in predicting elevated LV filling pressure and clinical outcomes compared to the 2009 version.

METHODS

We retrospectively identified 460 consecutive patients without atrial fibrillation or significant mitral valve disease who underwent transthoracic echocardiography within 24 hours of elective heart catheterization. LV end-diastolic pressure (LVEDP) and the time constant of isovolumic pressure decay (Tau) were determined. The association between DD grading by 2009 LVDD Recommendations and 2016 Recommendations with hemodynamic parameters and all-cause mortality were compared.

RESULTS

The 2009 LVDD Recommendations classified 55 patients (12%) as having normal, 132 (29%) as grade 1, 156 (34%) as grade 2, and 117 (25%) as grade 3 DD. Based on 2016 Recommendations, 177 patients (38%) were normal, 50 (11%) were indeterminate, 124 (27%) patients were grade 1, 75 (16%) were grade 2, 26 (6%) were grade 3 DD, and 8 (2%) were cannot determine. The 2016 Recommendations had superior discriminatory accuracy in predicting LVEDP (P<.001) but were not superior in predicting Tau. During median follow-up of 416 days (interquartile range: 5 to 2004 days), 54 patients (12%) died. Significant DD by 2016 Recommendations was associated with higher risk of mortality (P=.039, subdistribution HR1.85 [95% CI, 1.03-3.33]) in multivariable competing risk regression.

CONCLUSIONS

The grading algorithm proposed by the 2016 LV diastolic dysfunction Recommendations detects elevated LVEDP and poor prognosis better than the 2009 Recommendations.

A brief period of intensive cardiac rehabilitation improves global longitudinal strain and diastolic function after a first uncomplicated myocardial infarction

Objectives In patients with abnormal left ventricular ejection fraction (LVEF) after acute myocardial infarction (AMI), cardiac rehabilitation with physical training prevents cardiac remodelling. To define the role of rehabilitation in the recovery of ventricular function in less severe cases, we studied its effects on more refined indexes of left ventricular function in uncomplicated, low-risk patients. Methods and results Fifty-five patients underwent percutaneous coronary revascularization after uncomplicated first AMI. Thirty-four started cardiac rehabilitation with counselling and physical training; 21 patients did not train, followed a counselling program and were taken as controls. Echocardiography was performed at baseline, after rehabilitation or counselling program and at six months follow-up. We measured: global strain (GS%) with speckle tracking analysis, E/e' by tissue Doppler imaging (TDI), left ventricular elastance (K_LV) from the deceleration time (DT), LVEF, systolic and diastolic volumes, wall motion score index (WMSI). At baseline, groups had similar GS%, K_LV, LVEF, DT, E/e', systolic and diastolic volumes, WMSI. Rehabilitation increased peak VO₂ by 18% (P < 0.05) and improved GS%, K_LV, LVEF, E/e' and WMSI (P < 0.02) that were unchanged in controls. The improvement persisted at six months. Conclusions After a first uncomplicated AMI, abnormalities of left systolic and diastolic ventricular function may be present persisting over time despite a normal LVEF, which are fully reverted by cardiac rehabilitation.

Increased Left Ventricular Diastolic Stiffness Is Associated With Heart Failure Symptoms in Aortic Stenosis Patients With Preserved Ejection Fraction

BACKGROUND

Clinical risk factors associated with heart failure (HF) symptoms in aortic stenosis (AS) patients with preserved ejection fraction (EF) have not been fully identified. We hypothesized that left ventricular (LV) diastolic stiffness is associated with HF symptoms in patients with AS.

METHODS AND RESULTS

We retrospectively evaluated 275 patients with at least moderate AS (aortic valve area <1.5 cm²) and preserved EF (≥50%). LV diastolic stiffness was evaluated with the use of echocardiographic parameters, diastolic wall strain (DWS, a measure of LV wall stiffness), and K_LV (a marker of LV chamber stiffness). There were 69 patients with HF. Patients with HF were older, were more likely to be African American, had a higher body mass index, and had more hypertension and coronary artery disease (P < .05 for all). Aortic valve area index and mean pressure gradient across the aortic valve were not different between patients with and without HF. Despite similar echocardiographic parameters of AS severity, patients with HF had stiffer LV (DWS 0.21 ± 0.06 vs 0.25 ± 0.06 [P < .01], K_LV 0.17 ± 0.11 vs 0.13 ± 0.08 [P < .01]). Logistic regression analyses revealed that after adjusting for age, race, body mass index, history of hypertension, and coronary artery disease, LV diastolic stiffness parameters remained significantly associated with HF symptoms.

CONCLUSIONS

LV diastolic stiffness is independently associated with HF in AS patients with preserved EF.

Deliberations on Diastolic Heart Failure

Studies of left ventricular diastolic dysfunction and diastolic heart failure (DHF), published during the past 4 decades, include a prodigious number and wide variety of research efforts. This review report considers some of the historical literature and incorporates more recent information supporting the idea that patients with DHF constitute a subgroup of the heterogeneous population of patients with heart failure and a preserved ejection fraction. Clinical investigation, particularly therapeutic trials, should be directed at specific targets within the population of interest, not at the broad heart failure with preserved ejection fraction population. To accomplish this, it is important to stipulate criteria for the diagnosis of DHF and to limit our attention to specific subgroups or phenotypes.

Experimentally Increasing the Compliance of Titin Through RNA Binding Motif-20 (RBM20) Inhibition Improves Diastolic Function In a Mouse Model of Heart Failure With Preserved Ejection Fraction

BACKGROUND

Left ventricular (LV) stiffening contributes to heart failure with preserved ejection fraction (HFpEF), a syndrome with no effective treatment options. Increasing the compliance of titin in the heart has become possible recently through inhibition of the splicing factor RNA binding motif-20. Here, we investigated the effects of increasing the compliance of titin in mice with diastolic dysfunction.

METHODS

Mice in which the RNA recognition motif (RRM) of one of the RNA binding motif-20 alleles was floxed and that expressed the MerCreMer transgene under control of the αMHC promoter (referred to as cRbm20^ΔRRM mice) were used. Mice underwent transverse aortic constriction (TAC) surgery and deoxycorticosterone acetate (DOCA) pellet implantation. RRM deletion in adult mice was triggered by injecting raloxifene (cRbm20^ΔRRM-raloxifene), with dimethyl sulfoxide (DMSO)-injected mice (cRbm20^ΔRRM-DMSO) as the control. Diastolic function was investigated with echocardiography and pressure-volume analysis; passive stiffness was studied in LV muscle strips and isolated cardiac myocytes before and after elimination of titin-based stiffness. Treadmill exercise performance was also studied. Titin isoform expression was evaluated with agarose gels.

RESULTS

cRbm20^ΔRRM-raloxifene mice expressed large titins in the hearts, called supercompliant titin (N2BAsc), which, within 3 weeks after raloxifene injection, made up ≈45% of total titin. TAC/DOCA cRbm20^ΔRRM-DMSO mice developed LV hypertrophy and a marked increase in LV chamber stiffness as shown by both pressure-volume analysis and echocardiography. LV chamber stiffness was normalized in TAC/DOCA cRbm20^ΔRRM-raloxifene mice that expressed N2BAsc. Passive stiffness measurements on muscle strips isolated from the LV free wall revealed that extracellular matrix stiffness was equally increased in both groups of TAC/DOCA mice (cRbm20^ΔRRM-DMSO and cRbm20^ΔRRM-raloxifene). However, titin-based muscle stiffness was reduced in the mice that expressed N2BAsc (TAC/DOCAcRbm20^ΔRRM-raloxifene). Exercise testing demonstrated significant improvement in exercise tolerance in TAC/DOCA mice that expressed N2BAsc.

CONCLUSIONS

Inhibition of the RNA binding motif-20-based titin splicing system upregulates compliant titins, which improves diastolic function and exercise tolerance in the TAC/DOCA model. Titin holds promise as a therapeutic target for heart failure with preserved ejection fraction.

Exploration of pathomechanisms triggered by a single-nucleotide polymorphism in titin's I-band: the cardiomyopathy-linked mutation T2580I

Missense single-nucleotide polymorphisms (mSNPs) in titin are emerging as a main causative factor of heart failure. However, distinguishing between benign and disease-causing mSNPs is a substantial challenge. Here, we research the question of whether a single mSNP in a generic domain of titin can affect heart function as a whole and, if so, how. For this, we studied the mSNP T2850I, seemingly linked to arrhythmogenic right ventricular cardiomyopathy (ARVC). We used structural biology, computational simulations and transgenic muscle in vivo methods to track the effect of the mutation from the molecular to the organismal level. The data show that the T2850I exchange is compatible with the domain three-dimensional fold, but that it strongly destabilizes it. Further, it induces a change in the conformational dynamics of the titin chain that alters its reactivity, causing the formation of aberrant interactions in the sarcomere. Echocardiography of knock-in mice indicated a mild diastolic dysfunction arising from increased myocardial stiffness. In conclusion, our data provide evidence that single mSNPs in titin's I-band can alter overall muscle behaviour. Our suggested mechanisms of disease are the development of non-native sarcomeric interactions and titin instability leading to a reduced I-band compliance. However, understanding the T2850I-induced ARVC pathology mechanistically remains a complex problem and will require a deeper understanding of the sarcomeric context of the titin region affected.

Quantitative Comparison Between Amyloid Deposition Detected by (99m)Tc-Diphosphonate Imaging and Myocardial Deformation Evaluated by Strain Echocardiography in Transthyretin-Related Cardiac Amyloidosis

BACKGROUND

Management of cardiac amyloidosis (CA) is related to amyloid deposition. Our aim was to assess the effect of amyloid deposition on myocardial function.

METHODS AND RESULTS

Twenty-eight patients with transthyretin mutation and a group of 14 controls underwent echocardiography to quantify left ventricular (LV) dimensions, function, and global (G) longitudinal (L), radial (R) and circumferential (C) strain (S). (99m)Tc-3,3-diphosphono-1,2-propanodicarboxylic-acid-scintigraphy ((99m)Tc-DPD) was used to quantify CA. (99m)Tc-DPD revealed accumulation in 14/28 patients (CA group) and no accumulation (no-CA group) in 14. Cardiac accumulation was lower-than-bone uptake in 5 (mild-CA group) and higher-than-bone uptake in 9 (severe-CA group). Ejection fraction was similar among groups. GLS was lower (P<0.001) in the severe-CA group (-12.2±4.5) with respect to the no-CA group (-19.3±3.0) and to the control group (-20.9±2.5). Conversely, GCS and GRS were lower (P<0.05) in the mild-CA group (-10.8±4.1 and 9.5±5.7, respectively) with respect to the severe-CA group (-18.9±5.1 and 23.9±6.3 respectively), no-CA group (-19.2±4.1 and 28.4±10.2, respectively) and the control group (-23.9±4.4 and 29.9±8.7, respectively). A correlation was found between the scintigraphic heart retention index (HRI) and LV septal thickness (ρ=0.72), E/E' (ρ=0.46) and GLS (ρ=-0.40).

CONCLUSIONS

Myocardial deformation is impaired in a different stage of CA. The (99m)Tc-DPD HRI correlated well with morphologic, diastolic and strain abnormalities. (Circ J 2016; 80: 1998-2003).

Cardiac Imaging to Evaluate Left Ventricular Diastolic Function

Left ventricular diastolic dysfunction in clinical practice is generally diagnosed by imaging. Recognition of heart failure with preserved ejection fraction has increased interest in the detection and evaluation of this condition and prompted an improved understanding of the strengths and weaknesses of different imaging modalities for evaluating diastolic dysfunction. This review briefly provides the pathophysiological background for current clinical and experimental imaging parameters of diastolic dysfunction, discusses the merits of echocardiography relative to other imaging modalities in diagnosing and grading diastolic dysfunction, summarizes lessons from clinical trials that used parameters of diastolic function as an inclusion criterion or endpoint, and indicates current areas of research.

A mathematical model of pressure and flow waveforms in the aortic root

The differences in the pressure and flow waveforms in the aortic root have not been explained so far in a satisfactory mathematical way. It is a generally accepted idea that the existence of the reflected wave causes the differences in shapes of pressure and flow. In this paper, a mathematical model is proposed that explains the blood pressure and flow waveforms based on changes in left ventricular volume during blood ejection into the aorta. According to the model, a change in volume of the left ventricle during contraction can be mathematically presented with solutions of differential equations that describe the behavior of a second-order system. The proposed mathematical equations of pressure and flow waveforms are derived from left ventricular volume change and basic equations of fluid dynamics. The position of the reflected wave depends on the age and elasticity of arteries, and has an effect on the flow and pressure waveforms. The model is in acceptable agreement with the experimental data available.

What global diastolic function is, what it is not, and how to measure it

Despite Leonardo da Vinci's observation (circa 1511) that “the atria or filling chambers contract together while the pumping chambers or ventricles are relaxing and vice versa,” the dynamics of four-chamber heart function, and of diastolic function (DF) in particular, are not generally appreciated. We view DF from a global perspective, while characterizing it in terms of causality and clinical relevance. Our models derive from the insight that global DF is ultimately a result of forces generated by elastic recoil, modulated by cross-bridge relaxation, and load. The interaction between recoil and relaxation results in physical wall motion that generates pressure gradients that drive fluid flow, while epicardial wall motion is constrained by the pericardial sac. Traditional DF indexes (τ, E/E′, etc.) are not derived from causal mechanisms and are interpreted as approximating either stiffness or relaxation, but not both, thereby limiting the accuracy of DF quantification. Our derived kinematic models of isovolumic relaxation and suction-initiated filling are extensively validated, quantify the balance between stiffness and relaxation, and provide novel mechanistic physiological insight. For example, causality-based modeling provides load-independent indexes of DF and reveals that both stiffness and relaxation modify traditional DF indexes. The method has revealed that the in vivo left ventricular equilibrium volume occurs at diastasis, predicted novel relationships between filling and wall motion, and quantified causal relationships between ventricular and atrial function. In summary, by using governing physiological principles as a guide, we define what global DF is, what it is not, and how to measure it.

Cardiac function in survivors of childhood acute myeloid leukemia treated with chemotherapy only: a NOPHO-AML study

OBJECTIVES

We report cardiac function of patients treated for Childhood acute myeloid leukemia with chemotherapy only according to three consecutive Nordic protocols.

METHODS

Ninety-eight of 138 eligible patients accepted examination with standardized echocardiography. Results were compared with age- and sex-matched controls.

RESULTS

The median age was 3 yr at diagnosis (range 0-15), and the median time from diagnosis to study was 11 yr (4-25). All but one patient had received doxorubicin and 90% had received mitoxantrone. The median cumulative dose of daunorubicin equivalents was 300 mg/m(2) (210-525). Left ventricular fractional shortening (LVFS) and ejection fraction (LVEF) were lower in patients than in controls (32.6% (SD 4.0) vs. 35.2% (SD 3.4), P = 0.002 and 59.9% (SD 5.5) vs. 64.2% (SD 4.4), P = 0.001). The myocardial performance index (MPI) was higher in patients than in controls (0.32 (SD 0.081) vs. 0.26 (SD 0.074), P < 0.0001). Cumulative dose of doxorubicin but not mitoxantrone was related to lower LVFS (P = 0.037) and LVEF (P = 0.016). Longer follow-up was associated with lower LVFS (P = 0.034). Higher MPI was associated with young age at diagnosis (P = 0.04) and longer follow-up (P = 0.031).

CONCLUSIONS

In this study, most patients had cardiac function within normal limits and reported very few cardiac symptoms. However, compared with healthy controls, they had significantly reduced left ventricular function.

Usefulness of Combining Electrocardiographic and Echocardiographic Findings and Brain Natriuretic Peptide in Early Detection of Cardiac Amyloidosis in Subjects With Transthyretin Gene Mutation

Early noninvasive identification of cardiac amyloidosis (CA) is of growing clinical importance. Low voltage on electrocardiogram (ECG), increased left ventricular (LV) septal thickness (ST), and global longitudinal strain (GLS) on echocardiography, and elevated brain natriuretic peptides (BNP) are used as surrogates of CA. Thirty-five patients (50 ± 14 years, 22 women) underwent electrocardiography to analyze low-voltage QRS (<15 mV) pathologic Q waves, poor R-wave progression, ST-T abnormalities, and left bundle branch block. An ECG was considered abnormal if at least one ECG alteration was present. Echocardiography was used to analyze LVST, E/E', and GLS. All participants also had BNP blood testing. (99m)Tc-3,3-diphosphono-1,2 propanodicarboxylic acid scintigraphy assumed as a reference method showed CA in 18 patients (51%, CA group) and no accumulation in 17 patients (no CA group). In descending order of accuracy, LVST >14 mm, E/E' >6.6, GLS <14.1, BNP >129 pg/ml, and an overall abnormal ECG showed good capability to distinguish patients with and without CA. All these parameters were predictors of CA in univariate analysis, whereas low-voltage QRS showed the worst performance. LVST >14 mm (p = 0.002) was the best independent predictor of CA, achieving sensitivity of 78% and accuracy of 89%. However, an LVST >14 mm (p = 0.005) plus an abnormal ECG (p = 0.03) show together a greater sensitivity, equal to 89%, in identifying CA. An integrated evaluation of ECG and echocardiography is a sensitive and low-cost technical approach to identify CA in patients with transthyretin gene mutation.

Excess Linoleic Acid Increases Collagen I/III Ratio and "Stiffens" the Heart Muscle Following High Fat Diets

Controversy exists on the benefits versus harms of n-6 polyunsaturated fatty acids (n-6 PUFA). Although n-6 PUFA demonstrates anti-atherosclerotic properties, survival following cardiac remodeling may be compromised. We hypothesized that n-6 PUFA like linoleic acid (LA) or other downstream PUFAs like γ-linolenic acid or arachidonic acid alter the transforming growth factor-β (TGFβ)-collagen axis in the heart. Excess dietary LA increased the collagen I/III ratio in the mouse myocardium, leading to cardiac "stiffening" characterized by impaired transmitral flow indicative of early diastolic dysfunction within 5 weeks. In vitro, LA under TGFβ1 stimulation increased collagen I and lysyl oxidase (LOX), the enzyme that cross-links soluble collagen resulting in deposited collagen. Overexpression of fatty acid desaturase 2 (fads2), which metabolizes LA to downstream PUFAs, reduced collagen deposits, LOX maturation, and activity with LA, whereas overexpressing fads1, unrelated to LA desaturation, did not. Furthermore, fads2 knockdown by RNAi elevated LOX activity and collagen deposits in fibroblasts with LA but not oleic acid, implying a buildup of LA for aggravating such pro-fibrotic effects. As direct incubation with γ-linolenic acid or arachidonic acid also attenuated collagen deposits and LOX activity, we concluded that LA itself, independent of other downstream PUFAs, promotes the pro-fibrotic effects of n-6 PUFA. Overall, these results attempt to reconcile opposing views of n-6 PUFA on the cardiovascular system and present evidence supporting a cardiac muscle-specific effect of n-6 PUFAs. Therefore, aggravation of the collagen I/III ratio and cardiac stiffening by excess n-6 PUFA represent a novel pathway of cardiac lipotoxicity caused by high n-6 PUFA diets.

Role of Diastolic Function in Preserved Exercise Capacity in Patients with Reduced Ejection Fractions

BACKGROUND

Some patients with markedly reduced ejection fractions (EFs) (<35%) have preserved exercise performance greater than predicted for age and gender. Because diastolic function may be a determinant of exercise performance, this study was conducted to test the hypothesis that patients with preserved exercise tolerance despite EFs < 35% may have relatively normal diastolic function.

METHODS

Sixty-five subjects with EFs < 35% who underwent exercise Doppler echocardiography and had no inducible ischemia were retrospectively examined. Forty-five subjects with normal EFs (>60%) and preserved exercise capacity were analyzed as a control group.

RESULTS

Sixteen of 65 patients with EFs < 35% had greater than predicted normal exercise capacity for their age and gender, and the remaining 49 patients had reduced exercise capacity. Patients with reduced EFs and preserved exercise capacity had E/e' ratios (mean, 10 ± 4) similar to those of control subjects (mean, 10 ± 3) and lower than those with reduced exercise tolerance (mean, 16 ± 8) (P < .01). In addition, they had better diastolic filling patterns and smaller left atrial sizes than patients with EFs < 35% and reduced exercise capacity. Multivariate logistic regression analyses indicated that E/e' ratio was an independent predictor of preserved exercise capacity in patients with reduced EFs.

CONCLUSIONS

Relatively intact diastolic function contributes to preserved exercise capacity in patients with reduced EFs (<35%).

Grading diastolic function by echocardiography: hemodynamic validation of existing guidelines

Background

While echocardiographic grading of left ventricular (LV) diastolic dysfunction (DD) is used every day, the relationship between echocardiographic DD grade and hemodynamic abnormalities is uncertain.

Methods

We identified 460 consecutive patients who underwent transthoracic echocardiography within 24 h of elective left heart catheterization and had: normal sinus rhythm, no confounding structural heart disease, no change in medications between catheterization and echo, and complete echocardiographic data. Patients were grouped based on echocardiographic DD grade. Hemodynamic tracings were used to determine time constant of isovolumic pressure decay (Tau), LV end-diastolic pressure (LVEDP) and end-diastolic volume index at a pressure of 20 mmHg (EDVi20).

Results

Normal diastolic function was found in 55 (12.0 %) patients, while 132 (28.7 %) patients had grade 1, 156 (33.9 %) grade 2 and 117 (25.4 %) grade 3 DD. The median value for Tau was 46.9 ms for the overall population (interquartile range 38.6-58.1 ms), with a prevalence of a prolonged Tau (>48 ms) of 47.5 %. While there was an association between DD grade and Tau (p = 0.003), LV dysfunction (ejection fraction <50 %) was more strongly associated with increased Tau (p < 0.001) than was DD grade (p = 0.19). There was also an association between DD grade and LVEDP (p < 0.001), with both LV dysfunction (p = 0.029) and DD grade (p < 0.001) independently associated with LVEDP. Calculated EDVi20 was related to DD grade, but this relationship was driven by findings of paradoxically increased compliance in patients with severe DD.

Conclusions

Although echocardiographic grading of DD was related to invasive hemodynamics in this population, the relationship was modest.

Influence of Left Ventricular Stiffness on Hemodynamics in Patients With Untreated Atrial Septal Defects

BACKGROUND

Although left ventricular (LV) stiffening with age is believed to increase left-to-right shunting in patients with atrial septal defects (ASD), clinical data have not confirmed this. We sought determinants of the pulmonary-to-systemic flow ratio (Qp/Qs) in patients with untreated ASD.

METHODS AND RESULTS

We retrospectively studied 180 patients with ASD who underwent percutaneous ASD closure between 2007 and 2011. Qp/Qs and LV stiffness were measured before ASD closure.The median age of the subjects was 18 years, and 117 (65.0%) were female. The mean ASD size adjusted for square root of body surface area (BSA) was 14.4±4.2 mm/m, and the Qp/Qs was 2.28±0.74. Adjusted ASD size most strongly related to Qp/Qs (r=0.74, P<0.0001). Multivariate analysis revealed that LV stiffness was a significant predictor of Qp/Qs, independently of adjusted ASD size and vascular resistance (P=0.0015). Based on the multivariate model that accounts for the effects of LV stiffness and vascular resistance, the minimal adjusted diameter that can cause a Qp/Qs of 2.0 was predicted to be 7.3 mm/m.

CONCLUSIONS

Qp/Qs in ASD can change significantly depending on LV stiffness, suggesting that it would increase with age. An ASD >7.3 mm/m in diameter has the potential to cause significant left-to-right shunting, and may require closure regardless of hemodynamic status at the time of assessment.

Induction of Ankrd1 in Dilated Cardiomyopathy Correlates with the Heart Failure Progression

Progression of idiopathic dilated cardiomyopathy (IDCM) is marked with extensive left ventricular remodeling whose clinical manifestations and molecular basis are poorly understood. We aimed to evaluate the clinical potential of titin ligands in monitoring progression of cardiac remodeling associated with end-stage IDCM. Expression patterns of 8 mechanoptotic machinery-associated titin ligands (ANKRD1, ANKRD2, TRIM63, TRIM55, NBR1, MLP, FHL2, and TCAP) were quantitated in endomyocardial biopsies from 25 patients with advanced IDCM. When comparing NYHA disease stages, elevated ANKRD1 expression levels marked transition from NYHA < IV to NYHA IV. ANKRD1 expression levels closely correlated with systolic strain depression and short E wave deceleration time, as determined by echocardiography. On molecular level, myocardial ANKRD1 and serum adiponectin correlated with low BAX/BCL-2 ratios, indicative of antiapoptotic tissue propensity observed during the worsening of heart failure. ANKRD1 is a potential marker for cardiac remodeling and disease progression in IDCM. ANKRD1 expression correlated with reduced cardiac contractility and compliance. The association of ANKRD1 with antiapoptotic response suggests its role as myocyte survival factor during late stage heart disease, warranting further studies on ANKRD1 during end-stage heart failure.

Prediction of the impact of venoarterial extracorporeal membrane oxygenation on hemodynamics

Although venoarterial extracorporeal membrane oxygenation (ECMO) was developed to rescue patients with cardiogenic shock, the impact of ECMO on hemodynamics is often unpredictable and can lead to hemodynamic collapse. In this study, we developed a framework in which we incorporated ECMO into the extended Guyton's model of circulatory equilibrium and predicted hemodynamic changes in response to ECMO. We first determined the cardiac output (CO) curves of left and right heart (to generate the integrated CO curve) without ECMO in eight normal and seven dogs with left ventricular dysfunction. Using the CO curves obtained and standard parameters for the venous return surface, we predicted the circulatory equilibrium under various levels of ECMO support. The predicted total flow (native left heart flow plus ECMO flow), right atrial pressure (PRA), and left atrial pressure (PLA) matched well with those measured [total flow: coefficient of determination ( r2) = 0.99, standard error of estimate (SEE) = 5.8 ml·min−1·kg−1, PRA: r2 = 0.95, SEE = 0.23 mmHg, PLA: r2 = 0.99, SEE = 0.59 mmHg]. Lastly, we estimated the CO curves under ECMO support from minute changes in hemodynamics induced by change in ECMO. From the CO curves estimated, we predicted the circulatory equilibrium. The predicted total flow ( r2 = 0.93, SEE = 0.5 ml·min−1·kg−1), PRA ( r2 = 0.99, SEE = 0.54 mmHg), and PLA ( r2 = 0.95, SEE = 0.89 mmHg) matched reasonably well with those measured. A numerical simulation indicated that ECMO support may cause pulmonary edema, if right ventricular function is compromised. We conclude that the proposed framework may enhance the benefit and reduce the risk of ECMO support in patients with critical hemodynamic conditions.

Echocardiography and invasive hemodynamics during stress testing for diagnosis of heart failure with preserved ejection fraction: an experimental study

Inclusion of exercise testing in diagnostic guidelines for heart failure with preserved ejection fraction (HFpEF) has been advocated, but the target population, technical challenges, and underlying pathophysiological complexity raise difficulties to implementation. Hemodynamic stress tests may be feasible alternatives. Our aim was to test Trendelenburg positioning, phenylephrine, and dobutamine in the ZSF1 obese rat model to find echocardiographic surrogates for end-diastolic pressure (EDP) elevation and HFpEF. Seventeen-week-old Wistar-Kyoto, ZSF1 lean, and obese rats (n = 7 each) randomly and sequentially underwent (crossover) Trendelenburg (30°), 5 μg·Kg(-1)·min(-1) dobutamine, and 7.5 μg·Kg(-1)·min(-1) phenylephrine with simultaneous left ventricular (LV) pressure-volume loop and echocardiography evaluation under halogenate anesthesia. Effort testing with maximum O2 consumption (V̇o 2 max) determination was performed 1 wk later. Obese ZSF1 showed lower effort tolerance and V̇o 2 max along with higher resting EDP. Both Trendelenburg and phenylephrine increased EDP, whereas dobutamine decreased it. Significant correlations were found between EDP and 1) peak early filling Doppler velocity of transmitral flow (E) to corresponding myocardial tissue Doppler velocity (E') ratio, 2) E to E-wave deceleration time (E/DT) ratio, and 3) left atrial area (LAA). Diagnostic efficiency of E/DT*LAA by receiver-operating characteristic curve analysis for elevation of EDP above a cut-off of 13 mmHg during hemodynamic stress was high (area under curve, AUC = 0.95) but not higher than that of E/E' (AUC = 0.77, P = 0.15). Results in ZSF1 obese rats suggest that noninvasive echocardiography after hemodynamic stress induced by phenylephrine or Trendelenburg can enhance diagnosis of stable HFpEF and constitute an alternative to effort testing.

The N-terminal propeptide of type III procollagen in patients with acute coronary syndrome: a link between left ventricular end-diastolic pressure and cardiovascular events

Background

Despite the usefulness of N-terminal propeptide of type III procollagen (PIIINP) in detecting enhanced collagen turnover in patients with congestive heart failure, the value added by PIIINP to the use of clinical variables and echocardiography in relation to directly measured left ventricular (LV) end-diastolic pressure (EDP) and the outcome of acute coronary syndrome (ACS) has not been clearly defined.

Methods and Results

This study involved 168 adult patients with ACS, who underwent echocardiography, measurement of serum PIIINP levels, and cardiac catheterization. Pulsed wave tissue Doppler imaging (PWTDI), which revealed mean peak systolic (s′), early (e′), and late diastolic (a′) velocities, was carried out and the eas index of LV function was evaluated: e′/(a′×s′). The patients were divided into three study groups based on the degree of LVEDP – normal (<16 mmHg), intermediate (16–30 mmHg), and high (>30 mmHg) LVEDP. All patients were followed-up to determine cardiac-related death and revascularization. Patients with high LVEDP had significantly more PIIINP than those with intermediate or normal LVEDP (all post hoc p<0.05). The presence of coronary artery disease, the left atrial volume index (LAVI), the ratio of transmitral early and late diastolic flow velocities, a′, and the eas index were significantly correlated with LVEDP. According to multiple stepwise analysis, PIIINP, LAVI and the eas index were the three independent predictors of the level of LVEDP (PIIINP, p <0.001; LAVI, p = 0.007; eas index, p = 0.021). During follow-up (median, 24 months), 32 participants suffered from cardiac events, PIIINP and LAVI were significant predictors of cardiac mortality and hospitalization (PIIINP, hazard ratio (HR) 2.589, p = 0.002; LAVI, HR 1.040, p = 0.027).

Conclusions

PIIINP is a highly effective means to evaluate LVEDP in patients with ACS. The PIIINP is also correlated with cardiac mortality and revascularization, providing an additional means of evaluating and managing patients with ACS.

Right ventricular function in heart failure with preserved ejection fraction: a community-based study

BACKGROUND

The prevalence and clinical significance of right ventricular (RV) systolic dysfunction (RVD) in patients with heart failure and preserved ejection fraction (HFpEF) are not well characterized.

METHODS AND RESULTS

Consecutive, prospectively identified HFpEF (Framingham HF criteria, ejection fraction ≥50%) patients (n=562) from Olmsted County, Minnesota, underwent echocardiography at HF diagnosis and follow-up for cause-specific mortality and HF hospitalization. RV function was categorized by tertiles of tricuspid annular plane systolic excursion and by semiquantitative (normal, mild RVD, or moderate to severe RVD) 2-dimensional assessment. Whether RVD was defined by semiquantitative assessment or tricuspid annular plane systolic excursion ≤15 mm, HFpEF patients with RVD were more likely to have atrial fibrillation, pacemakers, and chronic diuretic therapy. At echocardiography, patients with RVD had slightly lower left ventricular ejection fraction, worse diastolic dysfunction, lower blood pressure and cardiac output, higher pulmonary artery systolic pressure, and more severe RV enlargement and tricuspid valve regurgitation. After adjustment for age, sex, pulmonary artery systolic pressure, and comorbidities, the presence of any RVD by semiquantitative assessment was associated with higher all-cause (hazard ratio=1.35; 95% confidence interval, 1.03-1.77; P=0.03) and cardiovascular (hazard ratio=1.85; 95% confidence interval, 1.20-2.80; P=0.006) mortality and higher first (hazard ratio=1.99; 95% confidence interval, 1.35-2.90; P=0.0006) and multiple (hazard ratio=1.81; 95% confidence interval, 1.18-2.78; P=0.007) HF hospitalization rates. RVD defined by tricuspid annular plane systolic excursion values showed similar but weaker associations with mortality and HF hospitalizations.

CONCLUSIONS

In the community, RVD is common in HFpEF patients, is associated with clinical and echocardiographic evidence of more advanced HF, and is predictive of poorer outcomes.

Viscoelastic properties of normal and infarcted myocardium measured by a multifrequency shear wave method: comparison with pressure-segment length method

Our aims were (i) to compare in vivo measurements of myocardial elasticity by shear wave dispersion ultrasound vibrometry (SDUV) with those by the conventional pressure-segment length method, and (ii) to quantify changes in myocardial viscoelasticity during systole and diastole after reperfused acute myocardial infarction. The shear elastic modulus (μ1) and viscous coefficient (μ2) of left ventricular myocardium were measured by SDUV in 10 pigs. Young's elastic modulus was independently measured by the pressure-segment length method. Measurements made with the SDUV and pressure-segment length methods were strongly correlated. At reperfusion, μ1 and μ2 in end-diastole were increased. Less consistent changes were found during systole. In all animals, μ1 increased linearly with left ventricular pressure developed during systole. Preliminary results suggest that μ1 is preload dependent. This is the first study to validate in vivo measurements of myocardial elasticity by a shear wave method. In this animal model, the alterations in myocardial viscoelasticity after a myocardial infarction were most consistently detected during diastole.

Influence of hyperhomocysteinemia on left ventricular diastolic function in Chinese patients with hypertension

OBJECTIVE

The aim of this study was to assess the effect of plasma homocysteine (Hcy) on left ventricular (LV) diastolic function in Chinese patients with essential hypertension.

PATIENTS AND METHODS

A total of 74 patients with hypertension were enrolled in the present study and were divided into two groups according to the plasma levels of Hcy: high levels of Hcy (Hhcy) group (n = 37) and control group (n = 37) with normal levels of homocysteine. The study participants consisted of 37 hypertensive patients with Hhcy and 37 hypertensive patients without Hhcy. Transthoracic Doppler echocardiography was performed to assess the LV diastolic function of the patients.

RESULTS

The plasma level of Hcy was directly related to LV diastolic echocardiographic parameters in patients with hypertension whereby the ratio E/e' was higher (12.7 ± 2.64 vs. 8.98 ± 1.55, p < 0.01), e'/a' was lower (0.59 ± 0.13 vs. 0.83 ± 0.20, p < 0.01), and the left atrial (LA) diameter was longer (43.4 ± 3.6 mm vs. 37.6 ± 5.0 mm, p < 0.01) in the Hhcy group than in the control group.

CONCLUSION

The LV diastolic function was significantly deteriorated in Chinese hypertensive patients with Hhcy and there were significant correlations between LV diastolic function indices and Hcy levels.

Diastolic Function in Normal Sinus Rhythm vs. Chronic Atrial Fibrillation: Comparison by Fractionation of E-wave Deceleration Time into Stiffness and Relaxation Components

Although the electrophysiologic derangement responsible for atrial fibrillation (AF) has been elucidated, how AF remodels the ventricular chamber and affects diastolic function (DF) has not been fully characterized. The previously validated Parametrized Diastolic Filling (PDF) formalism models suction-initiated filling kinematically and generates error-minimized fits to E-wave contours using unique load (x_o), relaxation (c), and stiffness (k) parameters. It predicts that E-wave deceleration time (DT) is a function of both stiffness and relaxation. Ascribing DT_s to stiffness and DTr to relaxation such that DT=DT_s+DT_r is legitimate because of causality and their predicted and observed high correlation (r=0.82 and r=0.94) with simultaneous (diastatic) chamber stiffness (dP/dV) and isovolumic relaxation (tau), respectively. We analyzed simultaneous echocardiography-cardiac catheterization data and compared 16 age matched, chronic AF subjects to 16, normal sinus rhythm (NSR) subjects (650 beats). All subjects had diastatic intervals. Conventional DF parameters (DT, AT, E_peak, E_dur, E-VTI, E/E') and E-wave derived PDF parameters (c, k, DT_s, DT_r) were compared. Total DT and DT_s, DT_r in AF were shorter than in NSR (p<0.005), chamber stiffness, (k) in AF was higher than in NSR (p<0.001). For NSR, 75% of DT was due to stiffness and 25% was due to relaxation whereas for AF 81% of DT was due to stiffness and 19% was due to relaxation (p<0.005). We conclude that compared to NSR, increased chamber stiffness is one measurable consequence of chamber remodeling in chronic, rate controlled AF. A larger fraction of E-wave DT in AF is due to stiffness compared to NSR. By trending individual subjects, this method can elucidate and characterize the beneficial or adverse long-term effects on chamber remodeling due to alternative therapies in terms of chamber stiffness and relaxation.

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.

The Challenge of Chamber Stiffness Determination in Chronic Atrial Fibrillation vs. Normal Sinus Rhythm: Echocardiographic Prediction with Simultaneous Hemodynamic Validation

Echocardiographic diastolic function (DF) assessment remains a challenge in atrial fibrillation (AF), because indexes such as E/A cannot be used and because chronic, rate controlled AF causes chamber remodeling. To determine if echocardiography can accurately characterize diastolic chamber properties we compared 15 chronic AF subjects to 15, age matched normal sinus rhythm (NSR) subjects using simultaneous echocardiography-cardiac catheterization (391 beats analyzed). Conventional DF parameters (DT, Epeak, AT, Edur, E-VTI, E/E') and validated, E-wave derived, kinematic modeling based chamber stiffness parameter (k), were compared. For validation, chamber stiffness (dP/dV) was independently determined from simultaneous, multi-beat P-V loop data. Results show that neither AT, Epeak nor E-VTI differentiated between groups. Although DT, Edur and E/E' did differentiate between groups (DTNSR vs. DTAF p < 0.001, EdurNSR vs. EdurAF p < 0.001, E/E'NSR vs. E/E'AF p < 0.05), the model derived chamber stiffness parameter k was the only parameter specific for chamber stiffness, (kNSR vs. kAF p <0.005). The invasive gold standard determined end-diastolic stiffness in NSR was indistinguishable from end-diastolic (i.e. diastatic) stiffness in AF (p = 0.84). Importantly, the analysis provided mechanistic insight by showing that diastatic stiffness in AF was significantly greater than diastatic stiffness in NSR (p < 0.05). We conclude that passive (diastatic) chamber stiffness is increased in normal LVEF chronic, rate controlled AF hearts relative to normal LVEF NSR controls and that in addition to DT, the E-wave derived, chamber stiffness specific index k, differentiates between AF vs. NSR groups, even when invasively determined end-diastolic chamber stiffness fails to do so.