Negative DNA supercoiling induces genome-wide Cas9 off-target activity

CRISPR-Cas9 is a powerful gene-editing technology; however, off-target activity remains an important consideration for therapeutic applications. We have previously shown that force-stretching DNA induces off-target activity and hypothesized that distortions of the DNA topology in vivo, such as negative DNA supercoiling, could reduce Cas9 specificity. Using single-molecule optical-tweezers, we demonstrate that negative supercoiling λ-DNA induces sequence-specific Cas9 off-target binding at multiple sites, even at low forces. Using an adapted CIRCLE-seq approach, we detect over 10,000 negative-supercoiling-induced Cas9 off-target double-strand breaks genome-wide caused by increased mismatch tolerance. We further demonstrate in vivo that directed local DNA distortion increases off-target activity in cells and that induced off-target events can be detected during Cas9 genome editing. These data demonstrate that Cas9 off-target activity is regulated by DNA topology in vitro and in vivo, suggesting that cellular processes, such as transcription and replication, could induce off-target activity at previously overlooked sites.

Phenotyping Acute Decompensated Heart Failure (ADHF)by a cardiac speckle tracking analysis

Background

The global longitudinal strain (GLS) evaluation by Speckle Tracking Echocardiography (STE) is an established non-invasive, highly reproducible echocardiographic prognostic index in Heart Failure (HF). In acute decompensated heart failure (ADHF), GLS has proved to have greater prognostic value than left ventricular ejection fraction (LVEF) in the categorization of HF. However, how GLS may change over hospital staying in ADHF and how it correlates with Left Atrial (LA) functioning and contractile reserve in this cohort of subjects is currently undefined.

Aims

To evaluate, in a cohort of ADHF patients, GLS extent of changes after targeted anti-congestion therapy and its correlation with LA mechanics and reservoir function.

Methods

Eighty-five ADHF patients (mean age 75.6±10.4 years, 59% males) were prospectively enrolled within 24 hours from admission to the emergency department (ED). In either the acute phase and at pre-discharge all patients underwent laboratory tests, Lung Ultrasonography (LUS), M-Mode, 2-Dimensions and Doppler Echocardiography. LA dynamics assessment was based on the evaluation of LA strain, particularly through Global-Peak Atrial Longitudinal Strain (GPALS). Strain analysis by STE was performed offline.

Results

From admission to discharge, despite decongestion as shown by a significant reduction of the number of B-lines measured at LUS and NT-proBNP at blood tests (B-lines: 22.2±17.1 vs. 6.5±5 p<0.001; NT-proBNP: 8738±948 ng/l vs 4227±659 ng/l p<0.001), we observed only minimal and non-significant changes in the average GLS (from −12.2±4% at admission to −12.5±3.8% at discharge; p=0.8) and GPALS (from 13.2±7.6% at admission to 13.6±7.8% at discharge; p=0.77) (Table 1). Interestingly, when evaluated with Pearson's coefficient, in the whole population a significant direct correlation was observed between GLS and GPALS values at discharge (r=0.6, 95% Confidence Interval (CI) 0.55–0.7; p<0.001) (Figure 1) as well as between ΔGLS and ΔGPALS (r=0.42 95% CI 0.21–0.59, p=0.02).

Conclusions

In patients hospitalized for ADHF a significant impairment of GLS occurs and no improvement is observed at discharge after decongestion. The LA dynamics correlates with, and is likely involved in, this lack of changes. In this subset of patients, the dissociation between decongestion and LV and LA dynamics evaluated by strain analysis suggest the importance to monitor these functional indicators in order to improve risk stratification and reduce early re-hospitalization for AHF.

Funding Acknowledgement

Type of funding sources: None.

The link between left atrial mechanics and the pulmonary circulatory-right ventricular uncouplings in acute decompensated heart failure

Background

The worsening of right ventricular (RV) function and its uncoupling to pulmonary circulation (Pc) represents a turning point in terms of clinical outcome in heart failure (HF) patients. Relate to this In this context, the deterioration of Left Atrial (LA) function, which physiologically act as a watershed between the LV and the right heart cavities, favors the development of pulmonary venous congestion and vascular remodeling, triggering congestion. This is most apparent in the setting of Acute Decompensated Heart Failure (ADHF), where LA dysfunction unmask pulmonary capillary hypertension. The link between the acute changes in LA dynamics and the adaptive/maladaptive hemodynamic RV-to-Pc coupling is not defined in the acute decompensated (AD) HF.

Purpose

To investigate, in a cohort of ADHF patients, the association between the degree of RV-to-Pc uncoupling, assessed by the ratio between tricuspid annular plane systolic excursion (TAPSE) to pulmonary artery systolic pressure (PASP), and LA mechanics, evaluated with Speckle Tracking Echocardiography (STE).

Methods

Eighty-five ADHF patients (mean age 75.6±10.4 years, 59% males) were prospectively enrolled within 24 hours from admission to the Emergency Department. In the acute phase all patients underwent cardiac echocardiography and laboratory blood testing. Patients were then stratified in tertiles according to TAPSE/PASP ratio (group I: <0.4 mm/mmHg; group II: 0.4 to 0.6 mm/mmHg and group III: >0.6 mm/mmHg) correlating the degree of RV-to-Pc with LA mechanics. LA function was evaluated analyzing LA strain at peak relaxation and STE analysis was performed offline.

Results

At baseline, patients exhibited a high prevalence of RV dysfunction, increased PASP and an impairment in terms of RV coupling to PC (average TAPSE/PASP at admission: 0.44±0.18 mm/mmHg). When stratified in tertiles according to TAPSE/PASP ratio (group I: <0.4 mm/mmHg; group II: 0.4 to 0.6 mm/mmHg and group III: >0.6 mm/mmHg), exhibited an exponential direct relationship between LA-Strain values at admission, with levels increasing progressively with the increment of the ratio (Figure 1). A linear correlation between the degree of RV-to-Pc uncoupling and a more severely depressed LA functioning was noticed (r=0.4, CI 95% 0.21–0.57; p<0.001) (Figure 2).

Conclusions

In ADHF, there is a strong association between RV to Pc uncoupling and echo-derived measures of LA mechanics. These data underscore the importance to detect and treating the LA mechanical properties to blunt the negative repercussions on the right heart ultimately impacting on the clinical evolution.

Funding Acknowledgement

Type of funding sources: None.

Cas12a target search and cleavage on force-stretched DNA

Using optical tweezers, we investigate target search and cleavage by CRISPR-Cas12a on force-stretched λ-DNA. Cas12a uses fast, one-dimensional hopping to locate its target. Binding and cleavage occur rapidly and specifically at low forces (≤5 pN), with a 1.8 nm rate-limiting conformational change. Mechanical distortion slows diffusion, increases off-target binding but hinders cleavage.

Left atrial dynamics and congestion status analysis in acute decompensated heart failure based on LVEF categorization

Background

Left atrial (LA) dynamics play a key role in the hemodynamics assessment of heart failure (HF). LA strain analysis by speckle tracking echocardiography (STE) has recently been introduced in clinical practice. In acute decompensated heart failure (ADHF), LA functional deterioration leads to worsening of pulmonary capillary hypertension and congestion, ultimately impacting prognosis. However, how LA size and function behaves in ADHF according to the different HF phenotypes has never been studied.

Purpose

To evaluate the diverse morphology and dynamics of the LA, along with a thorough congestion analysis, in ADHF patients with HFpEF, HFmrEF and HFrEF.

Methods

Eighty-five ADHF patients (mean age 75.6±10.4 years, 59% males) were prospectively enrolled within 24–48 hours from admission to the emergency department. In the acute phase all patients underwent a complete transthoracic echocardiography (TTE) and lung ultrasonography (LUS) associated with blood sample and a thorough clinical examination. LA mechanics was assessed with STE, through the evaluation of global peak atrial longitudinal strain (GPALS).

Results

Out of 85 patients, 51% were classified as HFrEF, 20% as HFmrEF and 29% as HFpEF. At admission, all patients exhibited a comparable degree of congestion, as testified by increased IVC max. diameter (HFpEF 19±7 mm vs HFrEF 20±6.3 mm vs HFmrEF 17±5.3 mm, p=0.167), incremented PASP (HFpEF 39.2±13.5 mmHg vs HFrEF 42±12 mmHg vs HFmrEF 35.3±10.1 mmHg, p=0.15) and a rising number of B-lines on LUS (HFpEF 20±12.8 vs HFrEF 24±17 vs HFmrEF 21±19, p=0.62). Increased NT-proBNP values in the cohort were also noted, with HFrEF exhibiting the highest levels (HFrEF 11747±1069 ng/l vs HFmrEF 6905±811 ng/l vs HFpEF 3918±374 ng/l; p<0.001). When evaluating LA size and dynamics in the different HF phenotypes (HFrEF, HFmrEF and HFpEF respectively) a significant difference among the three subgroups was noted with HFrEF patients exhibiting a greater LA dilation and a higher impairment in terms of LA reservoir function (lowest GPALS/LAVi ratio) compared to HFpEF patients, who showed relatively less enlarged LA chambers and more preserved dynamics. Interestingly, HFmrEF patients expressed the best coupling between LA function and dimension, with significantly reduced LA dimensions and a more preserved LA function compared to HFrEF and HFpEF (LAVi: HFpEF 50.7±16 ml/m2 vs HFrEF 53.9±15 ml/m2 vs HFmrEF 42.8±10.8 ml/m2, p=0.05*; GPALS HFpEF 17±9.1% vs HFrEF 10±4.85% vs HFmrEF 18.3±6.2%, p<0.001*) (Figure 1 and 2).

Conclusions

ADHF patients exhibit an heterogeneous response in terms of LA size and function according to LVEF categorization. The definition of subjects expressing the worst coupling between LA size and function appears of relevance in order to facilitate risk stratification and identify patients at higher risk of early re-hospitalization.

Funding Acknowledgement

Type of funding sources: None.

Stroke volume but not ejection fraction predicts prognosis in acute heart failure

Background

Heart failure (HF) patients are categorized according to left ventricular ejection fraction (LVEF), being such index both easily feasible and prognostic. However, the risk stratification of patients hospitalized for acute decompensated heart failure (ADHF) according to the absolute value of LVEF at presentation is unexplored and its prognostic significance has not been tested against stroke volume indexed (SVi).

Purpose

To examine the prognostic impact of SVi versus LVEF in patients hospitalized for ADHF (wet and warm phenotype).

Methods

Eighty-five ADHF patients (mean age 75.6±10.4 years, 59% males) were prospectively enrolled within 24–48 hours from admission to the emergency department. In the acute phase all patients underwent a complete transthoracic echocardiography (TTE) and lung ultrasonography (LUS) associated with blood sample and a thorough clinical examination. Patients were then stratified into two groups according to the presence or the absence of a preserved SVi at admission (SVi ≥35 ml/m2).

Results

During a median follow-up (FU) time of 12 months (IQR months 8–15 months) we observed a CV event rate of 28.2%. During the FU period 14 patients (16.5%) were re-hospitalized for ADHF, 7 patients died for CV reason (8.2%), 1 patient underwent mitral valve replacement for severe chronic mitral regurgitation, 1 patient was re-hospitalized for cardiac resynchronization therapy and 1 subject was re-hospitalized for acute coronary syndrome.

Interestingly, patients that had a preserved TTE-derived SVi at admission (SVi ≥35 ml/m2) exhibited a significantly higher survival, when compared to subjects that showed an impairment of cardiac output at rest (SVi <35 ml/m2) (log-rank: HR 5.5 CI 95% 2.1–14.3; p=0.04) (Figure 1). On the other hand, LVEF was not independently associated with the endpoint and HFrEF, HFmrEF and HFpEF patients showed a comparable median survival (Figure 2).

Conclusions

Although the categorization of LVEF in CHF patients bears a pivotal classificatory and prognostic role, its assessment in ADHF, may lack of prognostic value especially when compared to SVi which represents a better parameter to define high-risk subjects who benefit from closer monitoring.

Funding Acknowledgement

Type of funding sources: None.

Monitoring stroke volume changes in acute heart failure patients

Background

Stroke volume (SV) is the net result of cardiac dynamics and functional capacity. Notably, acute decompensated heart failure (ADHF) patients admitted highly congested and with a reduced SV (primarily wet and cold phenotype) exhibit a poorer prognosis. However, how SV may change in wet and warm phenotype during acute hospital setting remains undefined.

Purpose

To evaluate, in a cohort of ADHF patients, the pattern of SV changes during hospitalization.

Methods

Eighty-one ADHF patients (mean age 75.75±10.6 years, 59% males) warm and wet phenotype were prospectively enrolled within 24–48 hours from admission to the emergency department. In either the acute phase and at pre-discharge all patients underwent M-Mode, 2-Dimensions, Doppler and Speckle Tracking echocardiography (STE). SV and SV indexed (SVi) were estimated using the non-invasive doppler method multiplying the left ventricular outflow tract (LVOT) cross-sectional area (CSA) and the velocity time-integral (VTI) of the LVOT.

Results

From admission to discharge, despite a targeted decongestion we observed only minimal and non-significant changes in the average SV and SVi (SV: from 46.9±14.7 ml at admission to 47.2±15.12 at discharge, p=0.9; SVi: from 26.6±8.5 ml/m2 at admission to 27.1±8.4 ml/m2 at discharge, p=0.73). When we looked at those patients improving (Group I) vs non improving SV (Group II) we observed that subjects in Group I exhibited a significantly lower prevalence of mitral regurgitation (MR) both at admission (Group I: MR adm. 23% vs Group II: MR adm: 53% p<0.05) and at the pre-discharge (Group I: MR disch. 13.4% vs Group II: MR disch. 45% p<0.05), a significantly higher global peak atrial longitudinal strain (GPALS) at pre-discharge (Group I: GPALS disch. 17.25±6.5% vs Group II disch. 11±7.1%; p=0.04), along with a significantly greater improvement in terms of GPALS (ΔGPLAS) during hospitalization (Group I: from 13±6.9% to 17.25±6.5%, p=0.04; Group II: from 13.85±8.4% to 11±7.1%, p=0.6) (Figure 1). Interestingly, when evaluated with Pearson's coefficient, in the whole population a significant direct correlation was observed between ΔSV and ΔGPALS (r=0.67 95% CI 0.4–0.7, p<0.001) (Figure 2).

Conclusions

In ADHF patients, the wet and warm phenotype displays a decreased forward SV which does not improve after decongestion therapy on average variations. In this context, the coexistence of LA impairment and hemodynamically significant MR seems to play a key role whereas, LA functional properties recover at least in part in patients who are able to show a SV improvement. Further analysis are necessary to test whether a lack of SV improvement in the short term may impact the long-term outcome.

Funding Acknowledgement

Type of funding source: None

Adverse cardiovascular outcome predicted by left atrial strain in acute decompensated heart failure

Background

A significant proportion of patients hospitalized for acute decompensated heart failure (ADHF) are readmitted to the hospital within 30 days, resulting in a major social and economic burden. Thus, risk stratification and identification of targets of therapy is of basic importance. Non-invasive imaging modality such as transthoracic echocardiography (TTE) represents a cornerstone tool to approach this clinical scenario for early recognition of high-risk patients.

Purpose

To define whether left atrial (LA) dynamics, evaluated by means of speckle tracking echocardiography (STE), may represent a predictor of cardiac events and early re-hospitalization in patients admitted to the emergency department (ED) for ADHF, in comparison with other non-invasive established prognostic index in heart failure (HF) such as NT-proBNP, B-lines at lung ultrasonography (LUS) and right ventricular (RV) to Pulmonary Circulation (PC) uncoupling evaluated through Tricuspid Annular Plane Systolic Excursion (TAPSE)/Pulmonary Arterial Systolic Pressure (PASP) ratio.

Methods

Seventy patients (mean age 75.6±11 years, 57% males) presenting with ADHF were prospectively enrolled within 24–48 hours from admission. In the acute phase and at pre-discharge the following variables have been collected: NT-proBNP, B-lines, TAPSE/PASP ratio, Left Atrial Volume indexed (LAVi) and global-peak atrial longitudinal strain (G-PALS).

Results

During a median follow-up of nine months we observed 18 events consisting of 7 deaths, 8 re-hospitalizations for ADHF, 1 re-hospitalization for acute coronary syndrome, 1 stroke and 1 mitral valve replacement. Multivariate Cox-regression analysis identified LAVi and GPALS at discharge, along with NT-proBNP, B-lines and TAPSE/PASP ratio, as independent predictors of major adverse CV events (LAVi: p=0.04; GPALS: p=0.05; NT-proBNP: p<0.001; B-lines: p=0.03; TAPSE/PASP: p<0.001) (Table 1).

Conclusions

Short-term re-hospitalization in ADHF is crucial and the identification of a higher risk through sensitive and potentially new hemodynamic phenotypes is of relevance. Our findings, although preliminary, may suggest a primary role of LA dynamics in this context.

Funding Acknowledgement

Type of funding source: None

Right ventricular function and its coupling with the pulmonary circulation in acute heart failure

Background

The right ventricle (RV) is extremely sensitive to hemodynamic changes and increased impedance. In acute heart failure (AHF), the development of pulmonary venous congestion and the increase of left ventricular (LV) filling pressures favors pulmonary vascular adverse remodeling and ultimately RV dysfunction, leading to the onset of symptoms and to a further decay of cardiac dynamics.

Purpose

The aim of the study was to evaluate RV morphology and functional dynamics at admission and discharge in patients hospitalized for AHF, analyzing the role and the response to treatment of the RV and its coupling with pulmonary circulation (PC).

Methods

Eighty-one AHF patients (mean age 75.75±10.6 years, 59% males) were prospectively enrolled within 24–48 hours from admission to the emergency department (ED). In either the acute phase and at pre-discharge all patients underwent M-Mode, 2-Dimensional and Doppler transthoracic echocardiography (TTE), as well as lung ultrasonography (LUS), to detect an increase of extravascular lung water (EVLW) and development of pleural effusion. Laboratory tests were performed in the acute phase and at pre-discharge including the evaluation of NT-proBNP.

Results

At baseline we observed a high prevalence of RV dysfunction as documented by a reduced RV systolic longitudinal function [mean tricuspid annular plane systolic excursion (TAPSE) at admission of 16.47±3.86 mm with 50% of the patients exhibiting a TAPSE<16mm], a decreased DTI-derived tricuspid lateral annular systolic velocity (50% of the subjects showed a tricuspid s' wave<10 cm/s) and a reduced RV fractional area change (mean FAC at admission of 36.4±14.6%). Furthermore, an increased pulmonary arterial systolic pressure (PASP) and a severe impairment in terms of RV coupling to PC was detected at initial evaluation (mean PASP at admission: 38.8±10.8 mmHg; average TAPSE/PASP at admission: 0.45±0.17 mm/mmHg).

At pre-discharge a significant increment of TAPSE (16.47±3.86 mm vs. 17.45±3.88; p=0.05) and a reduction of PASP (38.8±10.8 mmHg vs. 30.5±9.6mmHg, p<0.001) was observed. Furthermore, in the whole population we assisted to a significant improvement in terms of RV function and its coupling with PC as demonstrated by the significant increase of TAPSE/PASP ratio (TAPSE/PASP: 0.45±0.17 mm/mmHg vs 0.62±0.20 mm/mmHg; p<0.001). Patients significantly reduced from admission to discharge the number of B-lines and NT-proBNP (B-lines: 22.2±17.1 vs. 6.5±5 p<0.001; NT-proBNP: 8738±948 ng/l vs 4227±659 ng/l p<0.001) (Figure 1). Nonetheless, no significant changes of left atrial and left ventricular dimensions and function were noted.

Conclusions

In AHF, development of congestion and EVLW significantly impact on the right heart function. Decongestion therapy is effective for restoring acute reversal of RV dysfunction, but the question remains on how to impact on the biological properties of the RV.

Funding Acknowledgement

Type of funding source: None

P960 Response of alveolo-capillar membrane diffusion to mitral regurgitation in heart failure with reduced ejection fraction

Background

In HFrEF patients, high pulmonary vascular resistances (PVR) imply a combined increase of both pre- and post-capillary pressures, associated with worse outcome. Mitral regurgitation (MR) may play a role in this complex physiopathology. We sought to investigate MR impact on lung DLCO and pulmonary vascular hemodynamic in HFrEF patient.

Methods

27 HFrEF patients (age 69 ± 9; LV EF 34 ± 6) underwent right heart catheterization, rest and exercise echocardiography, right ventricle 3D assessment and lung alveolo-capillary membrane DLCO. We identified 2 subgroups divided by normal (<3 WU, n= 20) or abnormal (>3 WU, n = 7) PVR.

Results

Abnormal PVR patients showed increased pulmonary artery pressures and TPG, reduced CO and pulmonary artery compliance. Total DLCO was not significantly different between groups. The membrane component (Dm) and the alveolar volume (Va) were significantly reduced in abnormal PVR group, while the capillary volume (VC) showed a strong trend toward higher values. Abnormal PVR group had a very high percentage of moderate-to-severe MR. The TASPE/SPAP ratio and the circumferential component of RV systolic function were significantly reduced in abnormal PVR group.

Conclusion

The presence of severe MR is associated with alveolar-capillary membrane remodeling (lower Dm), worse hemodynamic profile (higher PA pressures, lower PA compliance and higher PA resistance) and worse right ventricle to pulmonary circulation coupling (lower TAPSE/SPAP and lower 3D RV circumferential EF) in this cohort of HFrEF patients. These results confirm the adequacy of using therapeutic strategies aimed to solve valvular disease.

P1410 Right ventricle to pulmonary circulation coupling is primarily defined by the circumferential right ventricle function

Background

Right ventricle to pulmonary circulation (RV-PC) coupling plays a pivotal role during the physical effort. The RV-PC uncoupling can be easily identified by the TAPSE/SPAP ratio, a prognostic marker based on RV longitudinal function and its afterload (SPAP).We sought to explore the relationship between the functional capacity (peak VO2 and VE/VCO2) and the RV-PC coupling, using both a standard and 3D-based echocardiographic assessment of RV.

Methods

eighty-seven patients (age 72 ± 10 years; LV EF 53 ± 15%) underwent rest echocardiography with 3D RV assessment and cardiopulmonary exercise test. RV EF was measured using the 4D RV TomTec software. The 3D mesh of the RV model was post-processed using a custom developed software. This provided longitudinal (EFlong) and circumferential (EFcirc) components of EF. RV-PC coupling was assessed with the TAPSE/SPAP ratio and with similar parameters obtained by using 3D components of RV systolic function over SPAP (EF/SPAP, EFlong/SPAP and EFcirc/SPAP ratio). All variables were correlated with peakVO2 and VE/VCO2.

Results

Correlations between peakVO2 and TAPSE (0.409, p = 0.006), SPAP (-0.597, p < 0.001), RV EF (0.555, p < 0.001), RV EFlong (0.327, p = 0.03), RV EFcirc (0.587, p < 0.001) were modest, while TAPSE/SPAP (0.641, p < 0.001), EF/SPAP (0.751, p < 0.001), EFlong/SPAP (0.610, p < 0.001) and EFcirc/SPAP (0.775, p < 0.001) showed stronger correlations. VE/VCO2 showed a similar relationships although the correlations were weaker [TAPSE (-0.523, p <0.001), SPAP (0.617, p < 0.001), RV EF (-0.412, p = 0.006), RV EFlong (-0.232, p = 0.129), RV EFcirc (-0.454, p = 0.002), TAPSE/SPAP (-0.561, p < 0.001), EF/SPAP (-0.516, p = 0.001), EFlong/SPAP (-0.429, p = 0.008) and EFcirc/SPAP (-0.541, p < 0.001)].

Conclusions

RV-PC coupling is associated with both peak VO2 and VE/VCO2. The use of 3D-derived markers of RV-PC coupling showed a better correlation with the peak VO2, while there were no differences for VE/VCO2. The circumferential component of RV systolic function seems to emerge as a dominant determinant of RV-PC coupling, as well as of functional capacity.

P2603Impaired right ventricular force-frequency relationship in patients with heart failure is associated with diastolic dysfunction and worse functional capacity

Background

The force-frequency relationship (FFR) is an important intrinsic regulatory mechanism of cardiac contractility, related to changes in Ca2+ availability within the myocardial cell. In normal hearts this relationship is positive, so that an increase in contractile force is induced by elevation of the stimulation frequency. In heart failure (HF), the force-frequency relationship can be markedly depressed, but most studies focused their attention on left ventricular function and little is known about the right ventricle (RV).

Purpose

We aimed at performing a comprehensive analysis of HF phenotypes based on the right ventricular force-frequency relationship. To this purpose we stratified a large cohort of HF patients using the relationship between RV function (assessed by tricuspid annular plane systolic excursion, TAPSE) and heart rate (HR) during a symptom-limited cardiopulmonary exercise test (CPET).

Material and methods

We prospectively enrolled 184 HF patients, irrespective of their LV ejection fraction. We performed a stress echocardiographic evaluation using a tiltable cycle ergometer, recording standard images to assess LV systolic, diastolic, and valvular function.

We divided patients in 2 groups using the slope of the linear relationship between TAPSE and HR at rest and at peak exercise, as follows: slope ≥0,01 for “positive” FFR, slope <0,01 for “flat or negative” FFR.

Differences between groups were tested using unpaired t-tests for continuous variables (or Mann-Whitney U tests, when appropriate) and chi-square tests for categorical variables.

Results

55 patients had a “flat or negative” FFR: they were slighty older (age 70±10 vs. 66±12; p=0,036), but the 2 groups had similar clinical characteristics such as hypertension, diabetes or COPD rate.

Patients with a “flat or negative” FFR had a worse diastolic function, with higher left ventricular filling pressures (E/e' ratio 24±10 vs. 19±11 p=0,022) and left atrial volume (LAVi 55±29 ml/m2 vs. 44±20 ml/m2; p=0,009). No differences in LV ejection fraction, mitral regurgitation and pulmonary artery systolic pressure were observed between the groups.

TAPSE at rest was similar between the groups (18±5 mm vs. 18±4 mm; p=0,553) but significantly different at peak exercise (16±4 mm vs. 22±5 mm; p<0,001). Average peak heart rate was similar in the 2 groups.

Patients with a “flat or negative” FFR exhibited a significantly lower peak VO2 (11,6±3,0 ml/min/kg vs. 13,5±4,4 ml/min/kg; p=0,003), whereas they had a higher VE/VCO2 slope (35,1±9,6 vs. 32,3±8,2 p=0,05).

RV Force-Frequency relationship

Conclusion

The “flat or negative” right ventricular force-frequency relationship identifies a peculiar phenotype, with a higher grade of diastolic dysfunction and an impaired exercise capacity. The inability to adapt right ventricular contractility with increasing heart rate seems not related to RV afterload (similar PASP increase) but rather to an intrinsic failure of the right heart.

406Phenotyping acute decompensated heart failure by intrarenal venous flow and right ventricle-pulmonary circulation uncoupling

Background

Intrarenal venous blood flow (IRVF) has recently been used to assess renal haemodynamics in heart failure (HF).Different IRVF patterns have been described, with discontinuous IRVF related to a worse outcome compared to the continuous one.

Purpose

We aimed at studying the interaction between IRVF and the right heart dynamics thorough the study of right ventricular (RV) to pulmonary circulation (PC) coupling in acute decompensated (AD) HF patients.

Methods

92 ADHF patients underwent a transthoracic echocardiography followed by renal ultrasonography and laboratory tests. The IRVF was evaluated by Venous Impedance Index (VII)

Results

Dividing the population according to the different IRVF patterns allowed to phenotype the HF population. Patients with the worst IRVF pattern (monophasic) showed significantly higher prevalence of pulmonary hypertension and RV dysfunction with a lower TAPSE/PASP ratio. Patients with continuous IRVF pattern showed normal pulmonary pressures and RV function with a higher TAPSE/PASP ratio. A strong logarithmic correlation between VII and TAPSE/PASP ratio was observed (R2=0,5406).

At multivariate linear regression analysis, RV to PC uncoupling was identified as independent determinant of VII. TAPSE/PASP was inversely associated with VII (−0.55±0.16, p=0.0011). LVEF was not associated with VII (p=0.08).

No difference in renal function laboratory test was found while NT-proBNP was significantly higher in the IRVF monophasic group.

Patients characteristics Total (92) Continuous (32) Pulsatile (19) Biphasic (15) Monophasic (26) P value VII 0.49±0.36 0.11±0.06 0.38±0.12 0.74±0.05 0.95±0.02 <0.0001 LVEF (%) 43.9±16.1 51.4±13.4 41.6±15 43±15.3 34±16.3 0.002 TAPSE (mm) 16.7±5.5 20.1±5.1 13.9±2.7 17±6.5 13.7±4.3 <0.0001 PASP (mmHg) 41.6±14.5 30.9±6.9 42.9±9.3 52.6±12.6 50.3±16.3 <0.0001 TAPSE/PASP 0.46±0.26 0.69±0.24 0.33±0.08 0.34±0.14 0.29±0.11 <0.0001 Creatinine (mg/dL) 1.25±0.52 1.25±0.59 1.17±0.49 1.26±0.52 1.31±0.48 0.6 GFR (ml/min/1.73sqm) 58.9±2.2 59.6±22.9 60.2±17.8 61.6±23.5 55.4±16.9 0.7 NT-proBNP (ng/L) 5511±7764 2231±2463 6365±10318 7257±8173 7509±8380 0.004 VII = Venous impedance index; LVEF = left ventricle ejection fraction; TAPSE = Tricuspid annular plane systolic excursion; PASP = Pulmonary artery systolic pressure; IVC = Inferior vena cava; GFR = Glomerular filtration rate.

Conclusions

The identified correlation between RV to PC uncoupling and the IRVF pattern provides new evidence regarding the pathophysiological mechanisms of cardio-renal syndrome paving the way to interventions with proven effectiveness on the RV to reverse the unfavorable kidney hemodynamics and failure.

P3549Impact of mitral regurgitation on alveolo-capillar membrane diffusion: an hemodynamic and functional study

Background

In HFrEF patients, high pulmonary vascular resistances (PVR) reflect a combined increase of pre- and post-capillary pressures, associated with worse outcome. Mitral regurgitation (MR) may play a role in this complex physiopathology. We sought to investigate MR impact on lung DLCO and pulmonary vascular hemodynamic in HFrEF patient.

Methods

22 HFrEF patients (age 67±11; LV EF) underwent right heart catheterization, rest and exercise echocardiography, right ventricle 3D assessment and lung alveolo-capillary membrane DLCO. We identified 2 subgroups according to normal (<3 WU, n=17) or abnormal (>3 WU, n=5) PVR.

Results

Abnormal PVR patients showed increased pulmonary artery pressures and TPG, reduced CO and pulmonary artery compliance. Total DLCO was not significantly different between groups. The membrane component (Dm) and the alveolar volume (Va) were significantly reduced in abnormal PVR group, while the capillary volume (VC) showed a strong trend toward higher values. Abnormal PVR group had a very high percentage of moderate-to-severe MR. The TASPE/SPAP ratio and the circumferential component of RV systolic function were significantly reduced in abnormal PVR group.

Normal PVR (n=17) Abnormal PVR (n=5) p NTproBNP, ng/L 3021±2527 7023±8785 0.55 MR moderate-to-severe, n (%) 3 (19%) 4 (80%) 0.025 TAPSE/SPAP, mm/mmHg 0.4761±0.1695 0.2956±0.0739 0.019 3D RV global EF, % 40.616±9.350 29.486±14.062 0.119 3D RV longitudinal EF, % 15.611±7.773 12.086±9.694 0.497 3D RV circumferential EF, % 31.0567±6.5744 21.1746±11.5823 0.019 Lung diffusion of CO (DLCO), ml/min/mmHg 19.021±4.643 15.233±1.761 0.197 Dm ml/min/mmHg 26.8±8.2 17.8±4.1 0.047 VC, ml 110±77 247±152 0.121

Graphics

Conclusion

The presence of severe MR, in this cohort of HFrEF patients, is associated with alveolar-capillary membrane remodeling (lower Dm), worse hemodynamic profile (higher PA pressures, lower PA compliance and higher PA resistance) and worse right ventricle to pulmonary circulation coupling (lower TAPSE/SPAP and lower 3D RV circumferential EF), confirming the use of therapeutic strategies aimed at correction of valvular disease.

P6467Pressure-mediated changes in the ventricular septum shape during exercise in patients with pulmonary hypertension: a 3-d echocardiography study

Background

The role of interventricular (IV) septum in mediating the mechanical interaction between the two ventricles is well recognized. This interaction is promoted by several structural and hemodynamic determinants. We aimed at assessing the geometrical RV changes in patients with pulmonary hypertension (PH) compared to normal, evaluating RV curvature at rest and during stress testing addressing the specific role of pressure-induced changes in IV septum curvature.

Methods

Thirty-four subjects (15 controls; 19 PH patients) underwent RV real-time 3D full volume acquisition at rest and during exercise-echo. The 3D data were analysed off-line using the 4D RV TomTec software. The 3D mesh of the RV model was post-processed using a custom developed software. The value of mean regional curvature was assessed for the interventricular septum (IVS) at end-diastole (ED) and at end systole (ES).

Results

In controls the IVS curvature, assessed at end-diastole (ED) and end-systole (ES), was significantly (p<0.001) more concave (at rest −0.31±0.06 at ED, and −0.29±0.06 at ES; during exercise −0.28±0.09 at ED, and −0.28±0.08 at ES) than in PH patients (at rest −0.09±0.14 at ED, and −0.09±0.11 at ES ; during exercise −0.05±0.18 at ED, and −0.02±0.18 at ES). There was no significant variation in any of RV IVS curvatures between rest and exercise or between ES and ED. In PH subjects, IVS curvature at ES weakly increased from −0.09±0.11 (SD) at rest to −0.02±0.18 during exercise (p=0.179).Nonetheless, the degree of IVS curvature was strongly related to systolic pulmonary artery pressure (PASP), both at rest (r=0.743 at ES, p<0.01; r=0.794, p<0.001 at ED) and during exercise (r=0.823 at ES, p<0.0001; r=0.812 at ED, p<0.0001).

Conclusions

These data provide new perspectives on how the interventricular septum morphology adapts during exercise in PH patients vs controls. Changes in IVS curvature are linearly related to pulmonary pressure changes and occur with different slope (rest-exercise) in PH vs controls.

P4504Pulmonary circulatory-right ventricular uncoupling in acute decompensated heart failure: a key mediator of congestion

Background

The degree of congestion in patients hospitalized for acute decompensated heart failure (ADHF) is estimated using traditional non-invasive markers such as echo-derived inferior vena cava diameter (IVCD) and NT-proBNP levels. The deterioration of right ventricular (RV) function and its uncoupling to pulmonary circulation (Pc) represents a turning point in terms of prognosis and clinical outcome in patients affected by heart failure. However, how RV-to-Pc uncoupling correlates with markers of decompensation and congestion in ADHF patients has never been explored.

Purpose

To investigate, in a cohort of ADHF patients, the association between the degree of RV-to-Pc uncoupling, assessed by the ratio between tricuspid annular plane systolic excursion (TAPSE) to pulmonary artery systolic pressure (PASP), IVCD and right atrial pressure (RAP) estimated at echocardiography.

Methods

Fourty-six ADHF patients both with reduced and preserved EF (mean age 73.15±10.85 years, 60.8% males) admitted to the Cardiology Department were prospectively enrolled within 24–48 hours from admission. In the acute phase all patients underwent transthoracic echocardiography and laboratory blood tests. Patients were then stratified in tertiles according to TAPSE/PASP ratio (group I: <0.4 mm/mmHg; group II: 0.4 to 0.6 mm/mmHg and group III: >0.6 mm/mmHg) correlating the degree of RV-to-Pc with non-invasive markers of congestion such as NT-proBNP, IVC maximum diameter and RAP. Other echocardiographic parameters including left ventricular (LV) systolic function and LV filling pressures were considered.

Results

An exponential inverse relationship was found between NT-pro-BNP levels at admission with levels decreasing progressively with the increment of the ratio (Group I: 12828±10600 ng/l; Group II 5549±5383 ng/l; Group III 3695±3870 ng/l; p=0.004) (Figure 1a). An analogous correlation was observed when considering the IVC maximum diameter (Group I: 20.87±5.37 mm; Group II 18.08±4.35 mm; Group III 10.9±3.36 mm; p<0.001) (Figure 1b) and the RAP estimated at echocardiography (Group I: 12.875±5.25 mmHg; Group II 9.157±4.82 mmHg; Group III 4±1.61 mmHg; p<0.001) (Figure 1c).

In addition, progressively increasing values of LVEF (Group I: 28±11.3%; Group II 42±17.3%; Group III 49±11.8%; p=0.001) were detected from the lowest to the highest TAPSE/PASP tertiles. No correlation was observed in the three groups for E/E' values at admission (Group I: 17.17±6.7; Group II 19.42±8.36; Group III 15.92±5.7; p=0.5).

Figure 1

Conclusions

In ADHF, the association between RV to Pc uncoupling, echo-derived measures of congestion and natriuretic peptide levels is here described for the first time. The extent of RV dysfunction in ADHF deserves attention and seems to represent a critical and quite underestimated key mechanism between congestion resolution and in-hospital worsening HF.

6068Role of the circumferential right ventricle function in the right ventricle to pulmonary circulation coupling and functional capacity

Background

Right ventricle to pulmonary circulation (RV-PC) coupling plays a central role during the physical effort. The RV-PC uncoupling can be easily identified by the TAPSE/SPAP ratio, a prognostic marker based on RV longitudinal function and its afterload (SPAP).We sought to explore the relationship between the functional capacity (peak VO2 and VE/VCO2) and the RV-PC coupling, using both a standard and 3D-based echocardiographic assessment of RV.

Methods

Forty-four patients (age 71±10 years; LV EF 54±15%) received rest echocardiography with 3D RV assessment and cardiopulmonary exercise test. RV EF was measured using the 4D RV TomTec software. The 3D mesh of the RV model was post-processed using a custom developed software providing longitudinal (EFlong) and circumferential (EFcirc) components of EF. RV-PC coupling was assessed with the TAPSE/SPAP ratio and with similar parameters obtained using 3D components of RV systolic function over SPAP (EF/SPAP, EFlong/SPAP and EFcirc/SPAP ratio). All variables were correlated with peakVO2 and VE/VCO2.

Results

Correlations between peakVO2 and TAPSE (0.409, p=0.006), SPAP (−0.597, p<0.001), RV EF (0.555, p<0.001), RV EFlong (0.327, p=0.03), RV EFcirc (0.587, p<0.001) were modest, while TAPSE/SPAP (0.641, p<0.001), EF/SPAP (0.751, p<0.001), EFlong/SPAP (0.610, p<0.001) and EFcirc/SPAP (0.775, p<0.001) showed stronger correlations. VE/VCO2 showed a similar relationships although the correlations were weaker [TAPSE (−0.531, p<0.001), SPAP (0.614, p<0.001), RV EF (−0.409, p=0.006), RV EFlong (−0.232, p=0.129), RV EFcirc (−0.454, p=0.002), TAPSE/SPAP (−0.561, p<0.001), EF/SPAP (−0.516, p=0.001), EFlong/SPAP (−0.417, p=0.008) and EFcirc/SPAP (−0.534, p<0.001)].

Conclusions

RV-PC coupling is associated with both peak VO2 and VE/VCO2. The use of 3D-derived markers of RV-PC coupling showed a better correlation with the peak VO2 while there were no differences for VE/VCO2. The circumferential component of RV systolic function seems to emerge as a dominant determinant of RV-PC coupling, as well of functional capacity.

P3550Changes in intrarenal venous flow and right ventricle-pulmonary circulation coupling from in-hospital admission to discharge in decompensated heart failure patients

Background

Intrarenal venous blood flow (IRVF) has been used to assess renal haemodynamics in heart failure (HF). In stable euvolemic HF patients, IRVF patterns are correlated with clinical outcomes independently of conventional prognostic factors. No studies are available about the use of IRVF in decompensated HF (DHF).

Purpose

We aimed at establishing the possible clinical use of IRVF and his relationship with right ventricle (RV)-pulmonary circulation (PC) coupling in a cohort of DHF patients admitted at our clinic.

Methods

15 DHF patients (mean age 72.6±9.8 years) with signs and symptoms of volume overload underwent a transthoracic echocardiography followed by renal ultrasonography and routine laboratory tests at admission and at pre-discharge (in stable euvolemic state after diuretic treatment). The IRVF was evaluated by Venous Impedance Index (VII).

Results

At discharge after depletive treatment resulted in clinical decongestion, we observed a reduction of VII (from 0.74±0.28 to 0.42±0.40; p=0.016) associated with reduction of pulmonary pressures and better RV to PC coupling (TAPSE/PASP ratio from 0.33±0.18 to 0.46±0.15; p=0.031). No significant differences in resistive index (RI), LVEF and renal function laboratory tests were detected. Results are shown in Table 1.

Patients characteristics Admission Discharge p Value VII 0.74±0.28 0.42±0.40 0.02 LVEF (%) 43.7±17.5 42.7±16.3 0.87 TAPSE (mm) 14.9±4.1 17.1±3.6 0.14 PASP (mmHg) 51.9±15.2 39.4±11.6 0.02 TAPSE/PASP (mm/mmHg) 0.33±0.18 0.46±0.15 0.03 RI 0.8±0.1 0.7±0.1 0.11 Creatinine (mg/dL) 1.1±0.3 1.1±0.3 0.74 eGRF (mL/min/1.73 mq) 68.2±17.7 67.1±21 0.89 NT-proBNP (ng/L) 5663±5805.4 2047.2±2090.5 0.05 LVEF = left ventricular ejection fraction; BNP = natriuretic peptide; PASP = Syst art pulm press; RI = resistance index; TAPSE = tricuspid annular plane systolic excursion.

Conclusions

VII is a new non-invasive index that could identify renal hemodynamics alterations in HF patients. A high VII may be indicative of a congestive cardio renal syndrome in which an aggressive diuretic strategy can be set up with greater scientific evidence and the possibility of instrumental monitoring of its efficacy. Moreover, the development of drugs aimed at the improvement of the RV to PC coupling could lead to a better outcome in HF.

Longitudinal Strain Stress-Echo Evaluation of Aged Marginal Donor Hearts: Feasibility in the Adonhers Project

BACKGROUND

The Adonhers (aged donor heart rescue by stress-echo protocol) Project was created to resolve the current shortage of donor hearts. One of the great limits of stress echo is the operator dependency. Speckle-tracking echocardiography (STE), offering a quantitative objective analysis of myocardial deformation, may help to overcome this limit. This study aimed to verify feasibility of a stress-strain echo analysis in selection of aged donor hearts for heart transplant.

METHODS

From February 2014 to October 2015, 22 marginal candidate donors (16 men) ages 58 ± 4 years were initially enrolled. After legal declaration of brain death, all marginal donors underwent bedside echocardiography, with baseline and (when resting echocardiography was normal) dipyridamole (0.84 mg/kg in 6 minutes) stress echo. In all patients, left ventricular (LV) longitudinal myocardial deformation was obtained by STE in the 4-, 2-, and 3-chamber views, obtaining the average global longitudinal strain (GLS). GLS was assessed at baseline and at the peak of stress echo.

RESULTS

Baseline echocardiography showed wall motion abnormalities in 9 patients (excluded from donation). Stress echocardiography was performed in the remaining 13 patients. Results were normal in 8, who were uneventfully transplanted in marginal recipients. Stress results were abnormal in 5 (excluded from donation). STE was obtained in all cases (100% feasibility) and ΔGLS was significantly different between normal and pathological stress-echo (+13.2 ± 5.2 versus -6.1% ± 3.1%, P = .0001, respectively).

CONCLUSIONS

STE showed an excellent feasibility in analysis of LV myocardial longitudinal strain at baseline and at the peak of stress echo of marginal heart donors. Further experience is needed to confirm STE as a valuable additional mean to better interpret stress echo in marginal donors.

In vivo identification of nuclear factors interacting with the conserved elements of box C/D small nucleolar RNAs

The U16 small nucleolar RNA (snoRNA) is encoded by the third intron of the L1 (L4, according to the novel nomenclature) ribosomal protein gene of Xenopus laevis and originates from processing of the pre-mRNA in which it resides. The U16 snoRNA belongs to the box C/D snoRNA family, whose members are known to assemble in ribonucleoprotein particles (snoRNPs) containing the protein fibrillarin. We have utilized U16 snoRNA in order to characterize the factors that interact with the conserved elements common to the other members of the box C/D class. In this study, we have analyzed the in vivo assembly of U16 snoRNP particles in X. laevis oocytes and identified the proteins which interact with the RNA by label transfer after UV cross-linking. This analysis revealed two proteins, of 40- and 68-kDa apparent molecular size, which require intact boxes C and D together with the conserved 5',3'-terminal stem for binding. Immunoprecipitation experiments showed that the p40 protein corresponds to fibrillarin, indicating that this protein is intimately associated with the RNA. We propose that fibrillarin and p68 represent the RNA-binding factors common to box C/D snoRNPs and that both proteins are essential for the assembly of snoRNP particles and the stabilization of the snoRNA.