cGMP-dependent protein kinase 1α (PKG1α) promotes left ventricle (LV) compensation after pressure overload. PKG1-activating drugs improve heart failure (HF) outcomes but are limited by vasodilation-induced hypotension. Signaling molecules that mediate PKG1α cardiac therapeutic effects but do not promote PKG1α-induced hypotension could therefore represent improved therapeutic targets. We investigated roles of mixed lineage kinase 3 (MLK3) in mediating PKG1α effects on LV function after pressure overload and in regulating BP. In a transaortic constriction HF model, PKG activation with sildenafil preserved LV function in MLK3+/+ but not MLK3-/- littermates. MLK3 coimmunoprecipitated with PKG1α. MLK3-PKG1α cointeraction decreased in failing LVs. PKG1α phosphorylated MLK3 on Thr277/Ser281 sites required for kinase activation. MLK3-/- mice displayed hypertension and increased arterial stiffness, though PKG stimulation with sildenafil or the soluble guanylate cyclase (sGC) stimulator BAY41-2272 still reduced BP in MLK3-/- mice. MLK3 kinase inhibition with URMC-099 did not affect BP but induced LV dysfunction in mice. These data reveal MLK3 as a PKG1α substrate mediating PKG1α preservation of LV function but not acute PKG1α BP effects. Mechanistically, MLK3 kinase-dependent effects preserved LV function, whereas MLK3 kinase-independent signaling regulated BP. These findings suggest augmenting MLK3 kinase activity could preserve LV function in HF but avoid hypotension from PKG1α activation.

Background: Mixed lineage kinase 3 (MLK3) opposes pathologic cardiac remodeling, but its role in blood pressure (BP) has not been studied. MLK3 activates JNK signaling through kinase-dependent effects, and opposes RhoA activation through kinase-independent mechanisms, but the relevance of these mechanisms to BP is unknown. We investigated the effect of genetic deletion of MLK3 on BP. Methods and Results: Using ambulatory telemetric monitoring in 3 month old male mice, MLK3 -/- mice had significant hypertension compared to wild type (WT) littermates (WT systolic BP 121 ± 2 mmHg, MLK3-/- 162 ± 5 mmHg; n=3; p<0.05). The MLK3 kinase inhibitor URMC-099 (10 mg/kg IP) did not affect BP in WT mice. By contrast, inhibition of downstream RhoA dependent Kinase (ROCK) with Y-27632 (15 mg/kg) fully normalized BP in MLK3 -/- mice (SBP WT baseline 126 ± 2 mmHg; WT ROCK inhibitor 94 ± 2 mmHg; MLK-/- baseline 163 ±6 mmHg; MLK3 -/- ROCK inhibitor 94 ± 12 mmHg; n=5 WT, 9 MLK3-/-). Aortic pulse wave velocity was elevated in MLK-/- mice (2.7 ± 0.1 mm/ms WT vs 3.6 ± 0.2 mm/ms MLK3-/-; p<0.05) indicating increased aortic stiffness. Pressure myography in mesenteric resistance arterioles of MLK3 -/- mice revealed reduced distensibility compared to WT. Both pressure myography and direct histological measurement in resistance arterioles demonstrated reduced passive luminal diameter but preserved wall cross sectional area in MLK3-/- arterioles, indicating eutrophic remodeling. Compared with dispersed aortic smooth muscle cells from WT littermates, MLK3 -/- cells had increased actin stress fiber accumulation and cell area. Summary and Conclusions: These data demonstrate that MLK3 deletion leads to hypertension with increased arterial stiffness, reduced distensibility and eutrophic remodeling of resistance vessels, but retained BP responsiveness to downstream ROCK inhibition. Together with previous work, these findings support that MLK3 modulates cardiac remodeling through a kinase dependent mechanism while modulating blood pressure through kinase-independent effects. Because hypotension limits many heart failure therapies, delineating vascular versus cardiac mechanisms of MLK3 signaling has the potential to suggest novel approaches to heart failure treatment.

Myocardial hypertrophy is an independent risk factor for heart failure (HF), yet the mechanisms underlying pathological cardiomyocyte growth are incompletely understood. The c-Jun NH2-terminal kinase (JNK) signaling cascade modulates cardiac hypertrophic remodeling, but the upstream factors regulating myocardial JNK activity remain unclear. In this study, we sought to identify JNK-activating molecules as novel regulators of cardiac remodeling in HF. We investigated mixed lineage kinase-3 (MLK3), a master regulator of upstream JNK-activating kinases, whose role in the remodeling process had not previously been studied. We observed increased MLK3 protein expression in myocardium from patients with nonischemic and hypertrophic cardiomyopathy and in hearts of mice subjected to transverse aortic constriction (TAC). Mice with genetic deletion of MLK3 (MLK3-/-) exhibited baseline cardiac hypertrophy with preserved cardiac function. MLK3-/- mice subjected to chronic left ventricular (LV) pressure overload (TAC, 4 wk) developed worsened cardiac dysfunction and increased LV chamber size compared with MLK3+/+ littermates ( n = 8). LV mass, pathological markers of hypertrophy ( Nppa, Nppb), and cardiomyocyte size were elevated in MLK3-/- TAC hearts. Phosphorylation of JNK, but not other MAPK pathways, was selectively impaired in MLK3-/- TAC hearts. In adult rat cardiomyocytes, pharmacological MLK3 kinase inhibition using URMC-099 blocked JNK phosphorylation induced by neurohormonal agents and oxidants. Sustained URMC-099 exposure induced cardiomyocyte hypertrophy. These data demonstrate that MLK3 prevents adverse cardiac remodeling in the setting of pressure overload. Mechanistically, MLK3 activates JNK, which in turn opposes cardiomyocyte hypertrophy. These results support modulation of MLK3 as a potential therapeutic approach in HF. NEW & NOTEWORTHY Here, we identified a role for mixed lineage kinase-3 (MLK3) as a novel antihypertrophic and antiremodeling molecule in response to cardiac pressure overload. MLK3 regulates phosphorylation of the stress-responsive JNK kinase in response to pressure overload and in cultured cardiomyocytes stimulated with hypertrophic agonists and oxidants. This study reveals MLK3-JNK signaling as a novel cardioprotective signaling axis in the setting of pressure overload.

The nitric oxide (NO)-soluble guanylate cyclase (sGC)-cyclic guanosine monophosphate (cGMP) signalling pathway plays a fundamental role in modulating diverse physiological processes including blood flow, fibrosis, inflammation, and metabolism.sGC stimulators are small-molecule, heme-dependent agonists of sGC that synergize with and enhance endogenous NO signaling.As such, sGC stimulators may provide therapeutic benefits both in diseases associated with impaired NO signaling and in diseases where stimulation of this pathway will restore functional homeostasis.Data from our recent preclinical studies add to the growing body of evidence that sGC stimulators have direct effects on systemic and vascular inflammation, fibrosis, and metabolism.Ironwood is developing IW-1973 and IW-1701 as oral, once-daily sGC stimulators for both cardiovascular and non-cardiovascular systemic disease indications.Phase 1 studies in healthy human subjects demonstrated clear evidence of target engagement, attractive pharmacokinetic properties, and predicted hemodynamic effects, at well-tolerated doses.Phase 2 studies are currently ongoing in patients with achalasia, an esophageal motility disorder, and in patients with diabetes and hypertension.Preclinical characterization of IW-1973 and IW-1701 support the broad therapeutic potential and multi-faceted pharmacology of these compounds.Based on preclinical studies, IW-1973 has extensive distribution into organs including liver, heart, kidney, and lung, which may maximize effects on target organs while limiting systemic hemodynamic effects.The pharmacokinetic profile of IW-1701 has a narrow peak-to-trough ratio, which may provide more consistent pharmacological effect throughout the dosing interval.Ironwood is also developing IW-6463, a novel, CNS-penetrant sGC stimulator that shows target engagement and effects on regional blood flow in the brain.Preclinical data suggest that IW-6463 may be useful in treating CNS disorders including vascular dementia and Alzheimer's disease.We believe that sGC stimulation, alone or in combination with other mechanisms, may afford therapeutic benefit in multiple diseases.Furthermore, there may be an opportunity to provide targeted treatments by selecting compounds that are well-suited for specific diseases based on pharmacological profile, tissue distribution, pharmacokinetics, and route of administration.Competing interest

Background: cGMP-dependent protein kinase G I α (PKGIα) via its leucine zipper (LZ) domain prevents adverse cardiac remodeling. Identifying and characterizing PKGIα-LZ dependent substrates may reveal novel therapeutic targets in the myocardium. We previously identified the LZ-containing Mixed Lineage Kinase 3 (MLK3) as a potential PKGIα substrate. Further, MLK3 whole body knockout mice had increased LV hypertrophy and dysfunction after pressure overload. In this study we sought to further explore the PKGIα-MLK3 interaction, and to investigate MLK3 in human cardiomyopathy. Results: We first tested for a direct interaction between PKGIα and MLK3. Using affinity purified recombinant proteins we observed co-precipitation of PKGIα and MLK3 that was disrupted by mutation of the PKGIα LZ domain (LZ mutation: MLK3 binding decreased by 61.61% ±13.6, n=4). In mouse heart the interaction between native MLK3 and PKGIα was observed by co-immunoprecipitation (n=3). PKGIα phosphorylated MLK3 at the activation loop in vitro, which was attenuated by inhibiting PKGIα kinase function (n=3). We next tested if MLK3 regulates hypertrophy of cultured cardiomyocytes. Adult rat ventricular cardiomyocytes treated with the MLK3 inhibitor URMC-099 (100 nM, 48 hrs) exhibited increased cell size compared to vehicle treated cells (23.3% increase ± 3.64 SEM vs DMSO vehicle, n=3, 50 cells per treatment). Finally, we examined MLK3 expression in hearts from human patients with non-ischemic or hypertrophic cardiomyopathy. Compared to normal LV samples (NDRI, n=4), MLK3 expression was markedly elevated in both non-ischemic and hypertrophic cardiomyopathy LV samples (MLK3/GAPDH: non-ischemic: 6.26 ADU ± 0.85, n=9, hypertrophic: 6.97 ADU ± 1.42, n=8). Conclusion: These data support a model in which PKGIa directly binds and activates MLK3, leading in the cardiomyocyte to repression of cellular hypertrophy. Our findings in tissue from human failing hearts further suggest that MLK3 upregulation may act as a compensatory anti-remodeling signal in the setting of cardiac dysfunction, which ultimately becomes overwhelmed by pro-remodeling signals. More broadly our findings support that identifying PKGIa LZ-dependent substrates can reveal novel anti-remodeling molecules.

Background: The syndrome of heart failure (HF) arises from the pathologic process of cardiac remodeling. We have recently shown that the cGMP-dependent protein kinase I alpha (PKGIα) inhibits pathologic cardiac remodeling in vivo, and this effect requires the PKGIα leucine zipper LZ protein interaction domain. We have begun to explore PKGIa LZ-interacting proteins as potential novel anti-remodeling molecules. To this end, we recently identified that in the LV, PKGIα, through interactions mediated by the LZ domain, regulates a number of cardiovascular signaling molecules, including JNK and mixed lineage kinase 3 (MLK3). However, the expression of PKGIα, JNK, and MLK3 in different phenotypes of human heart failure remains incompletely understood. Methods and Results: In the current study, we tested the hypothesis that expression of PKGIα and its downstream effectors JNK and MLK3 become dysregulated in two phenotypes of remodeling and heart failure: nonischemic cardiomyopathy (NICM) and hypertrophic cardiomyopathy (HCM). We examined LV tissue from: 1) normal control hearts obtained through the national disease research interchange program (n = 4); 2) left ventricular assist device core tissue from patients with NICM (n = 7); and 3) surgical septal ablation tissue from patients with symptomatic HF from HCM (n = 9). We measured protein expression by Western blot and normalized expression to GAPDH. Data were expressed in arbitrary densitometric units (ADU). Compared with normal control LV tissue, normalized PKGIα expression increased significantly in both NICM and HCM LVs (fold increase vs. control: NICM 34.1 + /- 4.3; HCM 53.5 + /- 11.3; P < .05 NICM and HCM vs. control). Similarly, JNK expression increased in NICM and HCM compared with control (fold increase vs control: NICM 10.6 + /- 1.6; HCM 10.5 + /- 1.3; P < .05 NICM and HCM vs. control). Further, phosphorylated JNK increased in failing LVs (fold increase vs control: NICM 20.7 + /- 6.0; HCM +/- 19.9 + /- 4.6; P < .05 NICM and HCM). MLK3 expression increased in NICM and HCM patients compared with control (fold increase vs control: NICM 6.3 + /- 0.9; HCM 7.0 + /- 1.4; P < .05 NICM and HCM vs. control). Conclusions: These data identify that PKGIα, JNK, and MLK3 are expressed in the human heart and become highly upregulated in the setting of pathological hypertrophy both in NICM and HCM. We therefore interpret our results to support that the PKGIα-MLK3-JNK signaling system may function as an anti-remodeling mechanism in humans, which becomes upregulated in the failing human LV but ultimately may become overwhelmed by pathologic pro-remodeling signals. Augmenting PKGIα and its downstream substrates may represent a novel therapeutic strategy for certain types of heart failure.

BackgroundHeart failure is a significant contributor to cardiovascular mortality. cGMP inhibits cardiac remodeling in part via cGMP‐dependent protein kinase G I α (PKGIα). Knock in mice with a mutant PKGIα Leucine Zipper (LZ) have both decreased cardiac function and JNK activity after transaortic constriction (TAC). JNK is regulated by MAPKs including mixed lineage kinase 3 (MLK3) which contains an LZ interacting motif. We hypothesized PKGIα interacts with MLK3 via the PKGIα LZ domain to regulate JNK.ResultsThe MLK3‐PKGIα interaction was observed in mouse heart by co‐immunoprecipitation of MLK3 and PKGIα (n=3). In Cos1 cells MLK3 co‐precipitated with PKGIα but was prevented by mutation of the PKGIα LZ domain (n=3). In cardiomyocytes JNK stimulation by 8‐Br‐cGMP was prevented in MLK3‐depleted cells (siRNA, n=3). The role of MLK3 in the heart was tested by subjecting MLK3 knockout mice (MLK3‐/‐) to TAC (7 days). Compared to WT littermates MLK3‐/‐ hearts had increased hypertrophy and LV end diastolic pressure indicating advanced cardiac dysfunction (n=8‐10)ConclusionThese data reveal a novel interaction between PKGIα‐MLK3 that requires the LZ domain. In cardiomyocytes MLK3 is necessary for cGMP dependent JNK activation. Loss of MLK3 in vivo promotes adverse cardiac remodeling.This work was supported by the NIH.

Protein kinase G I alpha (PKGIα) counteracts hypertension and pathologic cardiac remodeling. These effects require the PKGIα leucine zipper (LZ) protein binding domain. However, PKGIα LZ-binding substrates mediating these effects remain incompletely understood. We previously demonstrated that Mixed Lineage Kinase 3 (MLK3) binds the PKGIα LZ domain in the heart. In the present study we hypothesized that MLK3 functions as a PKGIα substrate and cardiovascular effector. We observed that recombinant MLK3 precipitated with affinity purified PKGIα but not with LZ mutant PKGIα. When PKGIα was precipitated with RP-cGMP beads, which inhibit PKG kinase activity, we observed decreased PKGIα-MLK3 co-precipitation, supporting a requirement of PKGIα kinase activity for MLK3-PKGIa interaction. PKGIα phosphorylated MLK3 in vitro as assayed by Western blot. We next analysed mice with genetic deletion of MLK3. In the baseline state, MLK3-/- mice display normal cardiac function as assessed by echocardiography and invasive cardiac hemodynamics. MLK3-/- mice develop cardiac hypertrophy by 3 months of age (heart weight/tibia length 64.4 ± 1.9 mg/cm WT, 73.6 ± 2.1 mg/cm MLK3-/-; p<0.001; n=11 WT, 14 MLK3-/-). Compared with WT littermates, anesthetized MLK3-/- mice have elevated blood pressure (BP) (94.3 ± 2.1 mmHg WT, 109.3 ± 2.5 mmHg MLK3-/-; p<0.001). Conscious male MLK3-/- mice monitored continuously with implantable arterial radiotelemetry (10-12 weeks of age) had overt hypertension compared with WT littermates (Systolic BP: WT 121.5 ± 2.0 mmHg, MLK3-/- 161.6 ± 5.1 mmHg; p<0.01; Diastolic BP: WT 87.0 ± 2.9 mmHg, MLK3-/- 114.5 ± 2.7 mmHg; p<0.001; n=4 WT, 3 MLK3-/-). We observed no difference in baseline heart rate between genotypes. Chronic administration of hydralazine (250 mg/L) normalized BP in MLK3-/- mice, but did not completely inhibit cardiac hypertrophy. Further, in response to LV pressure overload by transaortic constriction (TAC), which equalized left ventricular (LV) systolic pressure between genotypes, MLK3-/- mice had increased LV hypertrophy (LV/Tibia length) as well as elevated LV end diastolic pressure, and worsening of LV ejection fraction, preload recruitable stroke work, and other LV systolic and diastolic indices (n=8-10), indicating advanced cardiac dysfunction. Together, our findings identify MLK3 as a direct PKGI substrate, and reveal that deletion of MLK3 leads to hypertension and pathologic cardiac hypertrophy. These findings support a model in which, in response to activation by PKGIα, MLK3 inhibits hypertension and cardiac hypertrophy. We conclude that identifying novel PKGIα LZ substrates, like MLK3, may reveal new candidate therapeutic targets for hypertension and heart failure.

We previously reported that Protein Kinase G Iα (PKGIα) mediates the anti-remodeling effect of cGMP in left ventricular (LV) pressure overload. We subsequently identified Mixed Lineage Kinase 3 (MLK3) to interact with and be regulated by PKGIα in cardiac tissue, suggesting that MLK3 functions as a PKGIα anti-remodeling effector.

Protein kinase G I α (PKGIα) inhibits cardiac remodeling, and this effect requires the PKGIα leucine zipper (LZ) binding domain. However, PKGIα LZ-dependent cardiac substrates remain poorly understood. Clinical trials of PKGI activating drugs have been limited to date by hypotension arising from vascular PKGI activation. Therefore, we explored downstream PKGIα substrates in the heart which may inhibit remodeling, yet circumvent the hypotensive effects of systemic PKGI activation. A screen for PKGIα LZ-interacting proteins identified: 1)cardiac myosin binding protein-C (cMyBP-C) and 2) mixed lineage kinase 3 (MLK3). cMyBP-C is a cardiac myocyte protein known to inhibit remodeling when phosphorylated. Co-precipitations with cGMP-conjugated beads confirmed the PKGIα-cMyBP-C interaction. Purified PKGIα phosphorylated cMyBP-C in vitro at Ser-273, Ser-282, and Ser-302. cGMP induced cMyBP-C phosphorylation at these sites in COS cells transfected with WT PKGIα, but not in cells transfected with either LZ mutant PKGIα or kinase-inactive PKGIα. In hearts of 9 month old PKGIα Leucine Zipper mutant mice, which have LV hypertrophy (LVH) and diastolic dysfunction, we observed decreased phosphorylated cMyBP-C as well as decreased total cMyBP-C, compared with WT littermate hearts. We next tested the effect of MLK3, which interacts with PKGIα in the heart, on remodeling in vivo. We performed 7 day Transaortic Constriction (TAC) on MLK3 KO mice and WT littermates (n=5 shams, 8 TAC per genotype). MLK3 KO TAC mice had increased LVH (LV mass/tibia length 71.1 ± 2.7 g/cm KO TAC vs 62.1 ± 2.7 WT TAC; p<0.05). Further, MLK3 KO mice developed overt CHF compared with WT littermates (LV end diastolic pressure 14.8 ± 1.9 mmHg KO TAC vs 7.7 ± 2.1 WT TAC, p <0.05), as well as accelerated decrements in LV preload recruitable stroke work (36.6 ± 11.9 mmHg/ul KO TAC vs 94.6 ± 12.9 WT TAC, p<0.05) and min dP/dt (-6292 ± 519 mmHg/s KO TAC vs −8157 ± 554 WT TAC , p <0.05). We observed no differences in LV structure or function between sham genotypes. These studies reveal 2 novel PKGIα anti-remodeling substrates, and they support that exploring PKGIα substrates in the heart may identify novel therapeutic targets to inhibit cardiac remodeling but avoid excessive PKGI induced vasodilation.

BackgroundThe significance of reduced pulse pressure in the right-sided circulation as a marker of right ventricular dysfunction prior to LVAD surgery remains uncertain. We evaluated the pulmonary artery pulsatility index (PaPi), a recently described hemodynamic metric, as a baseline predictor of post-operative RV failure following LVAD surgery.MethodsWe conducted a retrospective review of 104 consecutive LVAD implantations at our hospital. Demographic, clinical, hemodynamic and echocardiographic data were evaluated for their association with the development of RVF. RVF was defined as need for RVAD or inotrope dependence for greater than 14 days. PaPi was calculated as [(systolic pulmonary artery pressure-diastolic pulmonary artery pressure)/right atrial (RA) pressure]. Univariate analysis was performed to identify baseline predictors of RVF. Multivariate logistic regression was used to adjust for baseline RA pressure.ResultsRVF occurred in 21 of 104 patients (20%); all cases were due to prolonged inotropes. PaPi was lower among patients with RVF compared to those without (no RVF: mean 2.71± SD1.36 vs RVF: 1.35±0.58, P<0.01). RA pressure and RA to pulmonary capillary wedge pressure ratio (RA/PCWP) were also associated with RVF (Table 1). Other previously identified markers of RV function including RV stroke work index, mean pulmonary artery pressure, qualitative RV dysfunction (RVD) by 2D echo, and laboratory parameters were not associated with RVF (Table 1). After adjusting for RA pressure in a multivariate model, PaPi remained an independent predictor of RVF. A trend toward reduced survival (censored for transplant) at 180 days was observed in the RVF group (No RVF: 86% vs. RVF: 67%, P=0.059).ConclusionsTable 1Baseline variables of patients undergoing LVAD surgeryAll patients (n=104)No RVF (n=83)RVF (n=21)P valuesAge (years)55.9±12.155.8±12.756.2±9.60.90Gender (%male)7980760.77Destination Therapy (%)2525241.00Ischemic CM (%)3943240.14BUN29±1830±1829±160.88Cr1.44±0.591.48±0.631.32±0.430.29AST77±28577±31573±1690.96INR1.52±0.791.55±0.881.41±0.430.53Moderate-severe RVD (%)2424241.00HR (bpm)91±1592±1689±110.45MAP (mmHg)76±876±875±80.51RA (mmHg)12±510±417±5<0.0001mPAP (mmHg)35±936±933±90.29PCWP (mmHg)24±724±722±70.17CI (L/min/m2)2.45±0.682.42±0.662.55±0.760.44TPG (mmHg)11.6±5.911.6±5.411.8±7.90.87RA/PCWP0.50±0.200.43±0.140.79±0.13<0.0001RVSWI4.52±3.134.45±2.504.79±4.760.67PAPI2.43±1.362.71±1.361.35±0.58<0.0001 Open table in a new tab BackgroundThe significance of reduced pulse pressure in the right-sided circulation as a marker of right ventricular dysfunction prior to LVAD surgery remains uncertain. We evaluated the pulmonary artery pulsatility index (PaPi), a recently described hemodynamic metric, as a baseline predictor of post-operative RV failure following LVAD surgery. The significance of reduced pulse pressure in the right-sided circulation as a marker of right ventricular dysfunction prior to LVAD surgery remains uncertain. We evaluated the pulmonary artery pulsatility index (PaPi), a recently described hemodynamic metric, as a baseline predictor of post-operative RV failure following LVAD surgery. MethodsWe conducted a retrospective review of 104 consecutive LVAD implantations at our hospital. Demographic, clinical, hemodynamic and echocardiographic data were evaluated for their association with the development of RVF. RVF was defined as need for RVAD or inotrope dependence for greater than 14 days. PaPi was calculated as [(systolic pulmonary artery pressure-diastolic pulmonary artery pressure)/right atrial (RA) pressure]. Univariate analysis was performed to identify baseline predictors of RVF. Multivariate logistic regression was used to adjust for baseline RA pressure. We conducted a retrospective review of 104 consecutive LVAD implantations at our hospital. Demographic, clinical, hemodynamic and echocardiographic data were evaluated for their association with the development of RVF. RVF was defined as need for RVAD or inotrope dependence for greater than 14 days. PaPi was calculated as [(systolic pulmonary artery pressure-diastolic pulmonary artery pressure)/right atrial (RA) pressure]. Univariate analysis was performed to identify baseline predictors of RVF. Multivariate logistic regression was used to adjust for baseline RA pressure. ResultsRVF occurred in 21 of 104 patients (20%); all cases were due to prolonged inotropes. PaPi was lower among patients with RVF compared to those without (no RVF: mean 2.71± SD1.36 vs RVF: 1.35±0.58, P<0.01). RA pressure and RA to pulmonary capillary wedge pressure ratio (RA/PCWP) were also associated with RVF (Table 1). Other previously identified markers of RV function including RV stroke work index, mean pulmonary artery pressure, qualitative RV dysfunction (RVD) by 2D echo, and laboratory parameters were not associated with RVF (Table 1). After adjusting for RA pressure in a multivariate model, PaPi remained an independent predictor of RVF. A trend toward reduced survival (censored for transplant) at 180 days was observed in the RVF group (No RVF: 86% vs. RVF: 67%, P=0.059). RVF occurred in 21 of 104 patients (20%); all cases were due to prolonged inotropes. PaPi was lower among patients with RVF compared to those without (no RVF: mean 2.71± SD1.36 vs RVF: 1.35±0.58, P<0.01). RA pressure and RA to pulmonary capillary wedge pressure ratio (RA/PCWP) were also associated with RVF (Table 1). Other previously identified markers of RV function including RV stroke work index, mean pulmonary artery pressure, qualitative RV dysfunction (RVD) by 2D echo, and laboratory parameters were not associated with RVF (Table 1). After adjusting for RA pressure in a multivariate model, PaPi remained an independent predictor of RVF. A trend toward reduced survival (censored for transplant) at 180 days was observed in the RVF group (No RVF: 86% vs. RVF: 67%, P=0.059). ConclusionsTable 1Baseline variables of patients undergoing LVAD surgeryAll patients (n=104)No RVF (n=83)RVF (n=21)P valuesAge (years)55.9±12.155.8±12.756.2±9.60.90Gender (%male)7980760.77Destination Therapy (%)2525241.00Ischemic CM (%)3943240.14BUN29±1830±1829±160.88Cr1.44±0.591.48±0.631.32±0.430.29AST77±28577±31573±1690.96INR1.52±0.791.55±0.881.41±0.430.53Moderate-severe RVD (%)2424241.00HR (bpm)91±1592±1689±110.45MAP (mmHg)76±876±875±80.51RA (mmHg)12±510±417±5<0.0001mPAP (mmHg)35±936±933±90.29PCWP (mmHg)24±724±722±70.17CI (L/min/m2)2.45±0.682.42±0.662.55±0.760.44TPG (mmHg)11.6±5.911.6±5.411.8±7.90.87RA/PCWP0.50±0.200.43±0.140.79±0.13<0.0001RVSWI4.52±3.134.45±2.504.79±4.760.67PAPI2.43±1.362.71±1.361.35±0.58<0.0001 Open table in a new tab