Relaxin-2 and Soluble Flt1 Levels in Peripartum Cardiomyopathy: Results of the Multicenter IPAC Study

Abstract

Background

Peripartum cardiomyopathy (PPCM) is an uncommon disorder with unknown etiology. Angiogenic imbalance may contribute to its pathophysiology. We explore the association of vascular hormones with myocardial recovery and clinical outcomes in PPCM.

Methods and Results

In 98 women with newly diagnosed PPCM enrolled in the Investigation in Pregnancy Associated Cardiomyopathy (IPAC) study, serum was obtained at baseline for analysis of relaxin-2, prolactin, soluble fms-like tyrosine kinase 1 (sFlt1), and vascular endothelial growth factor (VEGF). Left ventricular ejection fraction (LVEF) was assessed by echocardiography at baseline and 2, 6 and 12 months. Mean age was 30 ± 6 years, with baseline LVEF 0.35 ± 0.09. Relaxin-2, prolactin, and sFlt1 were elevated in women presenting early postpartum, but declined rapidly and were inversely correlated with time from delivery to presentation. In tertile analysis, higher relaxin-2 was associated with smaller left ventricular systolic diameter (p=0.006) and higher LVEF at 2 months (p=0.01). This was particularly evident in women presenting soon after delivery (p=0.02). No relationship was evident for myocardial recovery and prolactin, sFlt1 or VEGF levels. sFlt1 levels were higher in women with higher New York Heart Association (NYHA) functional class (p=0.01) and adverse clinical events (p=0.004).

Conclusions

In women with newly diagnosed PPCM, higher relaxin-2 levels soon after delivery were associated with myocardial recovery at 2 months. In contrast, higher sFlt1 levels correlated with more severe symptoms and major adverse clinical events. Vascular mediators may contribute to development of PPCM and influence subsequent myocardial recovery.

Clinical Trial Registration Information

NCT01085955 https://clinicaltrials.gov/ct2/show/NCT01085955

INTRODUCTION

Peripartum cardiomyopathy (PPCM) is characterized by the development of heart failure late in pregnancy or in the months following delivery (1). Incidence varies geographically and in the Unites States is estimated at 1 in 1,000–4,000 live births (2,3,4,5,6). Presentation, clinical course, and outcomes are heterogeneous and can be associated with significant morbidity and mortality (1). In a recent prospective, multi-center study of 100 women with PPCM (Investigations in Pregnancy Associated Cardiomyopathy [IPAC]), 13% of patients suffered major events or had persistent severe cardiomyopathy (7). Factors associated with poorer outcomes include left ventricular dilation, severely depressed left ventricular systolic function, black race, later presentation, and higher body mass index (7,8,9,10).

The etiology of PPCM is unknown. Suggested causes include genetic predisposition, hormonal abnormalities, abnormal immune response, and inflammation (11,12). Recently it has been proposed that biological mediators with hemodynamic or vascular effects that are produced in the pregnant or peripartum state may play a role in the pathogenesis of PPCM (13,14,15). One of these factors is relaxin-2, a hormone produced in the corpus luteum of the ovary and in the heart (16,17). Relaxin-2 increases during pregnancy with hemodynamic and vasoactive effects including increased cardiac output, plasma volume, heart rate, and renal blood flow and lower vascular resistance (18). In addition, relaxin-2 has anti-inflammatory, angiogenic, and antifibrotic properties (16). Both the vasodilatory and angiogenic effects of relaxin-2 are mediated in part by vascular endothelial growth factor (VEGF) (19,20), which may exert a protective effect in heart failure of multiple etiologies (21). This understanding has led to investigation of relaxin as a therapeutic target in heart failure (22) and raises the possibility of a role in treatment of PPCM.

Another biological factor proposed to contribute to PPCM is prolactin, a pituitary hormone that is secreted in the peripartum period and stimulates lactation (23). Under conditions of oxidative stress, prolactin is proteolytically cleaved to a 16 kDa fragment that has deleterious effects on endothelial cells and promotes inflammation and fibrosis. Higher levels of this angiostatic fragment, and the resulting angiogenic imbalance in the myocardium, have been hypothesized to play a role in the pathophysiology of PPCM (24). Another anti-angiogenic factor released from the placenta and endothelial cells in mid to late pregnancy is soluble fms-like tyrosine kinase 1 (sFlt1 or vascular endothelial growth factor receptor 1). sFlt1 peaks at delivery and inhibits the activity of VEGF, leading to endothelial dysfunction and further angiogenic imbalance (14,25). Increased levels of sFlt1 may play an important role in the development of PPCM in some women (14,15), and recent data suggest that therapy targeting these pathways can rescue mouse models of PPCM (14,26). We report the analysis of relaxin-2, prolactin, sFlt1, and VEGF levels and their relationship to recovery of left ventricular function and clinical outcomes in the IPAC cohort.

METHODS

Cohort

As previously reported, 100 women with newly diagnosed PPCM were enrolled at 30 centers (Appendix) between December 2009 and September 2012All women were at least 18 years of age and had no previous history of cardiac disease an estimated clinical left ventricular ejection fraction (LVEF) ≤ 045 and an evaluation consistent with non-ischemic cardiomyopathyWomen with significant valvular disease coronary disease bacterial septicemia ongoing drug or alcohol abuse history of chemotherapy or chest radiation within 5 years or a history of a previous cardiomyopathy were excluded

Protocol

The study protocol was approved by the institutional review boards at all participating centers, and informed consent was obtained from all subjects. At the time of enrollment, demographic information, including self-designated race, previous clinical evaluation and current medical therapy, was recorded. Women were followed until one year post-partum. All hospitalizations and major cardiac events including death, cardiac transplantation, or implantation of a left ventricular assist device (LVAD) were recorded.

Left ventricular function

All subjects had an echocardiogram to assess LVEF at the time of enrollment and at 6 and 12 months post-partum. In addition, women enrolled early (within six weeks postpartum, n=66) had a repeat assessment of left ventricular function at 2 months. Left ventricular (LV) volumes and LVEF were assessed in a core laboratory (University of Pittsburgh) using biplane Simpson’s rule with manual tracing of digital images. Left ventricular end-diastolic diameter (LVEDD) and left ventricular systolic diameter (LVSD) were assessed in the parasternal long-axis view. A subset of studies (22 of 310, 7%) were not available for assessment by the core laboratory due to format, and LVEF calculated locally was used.

Biomarker assays

Serum was collected on 98 of 100 subjects at the time of entry, shipped overnight at room temperature to the core laboratory (University of Pittsburgh), and stored at −80 degrees Celsius until the time of analysis. The following ELISAs were obtained from R&D Systems (Minneapolis, MN): Human Prolactin (Cat. No. DPRL00) was run with 50μl of undiluted sample per well in duplicate; Human Relaxin (Cat. No. DRL200) was run with 50μl of undiluted sample per well in duplicate; Human sFlt1 (Cat. No. DVR100B) was run with 100μl of a 1:2 dilution per well in duplicate. Prolactin, relaxin and sFlt1 ELISAs were read at 450nm on a Packard Spectracount instrument, ALPCO (Salem, NH). VEGF was run on a MSD (Meso Scale Diagnostics, Rockville, MD). Human Cytokine Panel 1 was run on a multiplex plate (Cat. No. K15050D) with 50μl of a 1:2 diluted sample per well in duplicate, read on an MSD QuickPlex SQ120 instrument and analyzed using the MSD software.

Statistical analysis

The association of biomarker level with days post-partum was analyzed by Spearman correlation for non-normally distributed variables. To further evaluate the decline in biomarker levels with increasing days post-partum, subjects were divided into quartiles based on days post-partum to enrollment and mean biomarker levels in quartiles compared by a general linear model (GLM) ANOVA. For examination of demographics, medical therapy and clinical characteristics by time post-partum (quartiles), GLM and Fisher exact tests were used to compare continuous and categorical variables between groups respectively.

Biomarker tertile analysis and change in LVEF over time

Since data was collected from 30 centers, we examined the effect of the 30 centers on LVEF at 2 months using variance components analysis and observed that center of enrollment had minimal effect on LVEF at 2 months (Var (center) = <1%; estimated using restricted maximum likelihood estimation and ANOVA methods). Analysis subsequently ignored the effect of center of enrollment on this outcome. Similar analyses for all outcomes showed minimal effect of center, and therefore site of enrollment was similarly excluded from further modelling considerations. To analyze the association of biomarkers on the improvement of LVEF over time, the mean LVEF at four time points (early, 2 months, 6 months and 12 months) was compared for the entire cohort (n=98) by tertiles of biomarker level, comparing the mean LVEF at each time point by general linear model for subjects with high, intermediate, and low biomarker levels. In addition, given that for relaxin-2, prolactin and sFlt1, the highest biomarker levels were primarily noted early, the tertile analysis was repeated for each biomarker just in subjects presenting early, i.e. the first quartile, days 0–11 post-partum.

New York Heart Association (NYHA) class and event free survival

For comparison of NYHA class, mean biomarker levels for subjects in each class were compared by GLM. For outcomes, an event was defined as death, cardiac transplantation, or LVAD implantation. Event-free survival was compared by tertile of biomarker level using the Kaplan-Meier log rank method.

RESULTS

Time postpartum

Subjects were enrolled from 0 to 95 days post-partum. The demographics of the IPAC cohort and levels of relaxin-2, prolactin, sFlt1, and VEGF are listed in Table 1 by quartiles of days postpartum to presentation (0 to 11 days, 12 to 24 days, 25 to 51 days and 52 to 95 days). Subjects presenting earlier post-partum were less likely to be black and had a significantly higher NYHA class. Relaxin-2, prolactin, and sFlt1 were significantly and inversely correlated with the days postpartum to presentation, while VEGF was not (Spearman correlations for relaxin-2 r= −0.0.42, p=0.00001; prolactin r= −0.51, p<0.00001; sFlt1 r= −0.39, p= 0.0002; VEGF r= −0.07, p=0.48). The comparison of biomarker levels by quartiles of days postpartum to entry demonstrated significantly higher levels of relaxin-2 and sFlt1 in subjects presenting in the first quartile (0 to 11 days). Relaxin-2 and sFlt1 levels declined rapidly in the later quartiles to levels similar to those reported in non-postpartum subjects. Similar findings were evident for prolactin while no such relationship was evident for VEGF (Figure 1).

Table 1.

Demographics and clinical characteristics by quartile of days post-partum to enrollment

	All (n=100)	First Quartile (0–11 days) (n=25)	Second Quartile (12–24 days) (n=27)	Third Quartile (25–51 days) (n=25)	Fourth Quartile (52–95 days) (n=23)	P value
Age, years	30 ± 6	29 ± 7	28 ± 6	33 ± 5	30 ± 6	0.23
% NYHA* class (I/II/III/IV)	12/46/25/17	0/36/32/32	25/28/36/12	25/28/16/29	50/24/16/12	0.002
% Black	30	12	26	36	48	0.005
% Diabetes	11	12	0	20	13	0.40
% Hypertension	45	44	37	60	39	0.81
HR†, bpm	86 ± 16	94 ± 19	80 ± 14	83 ± 14	87 ± 16	0.25
SBP‡, mm Hg	112 ± 17	116 ± 15	113 ± 16	115± 18	102 ± 17	0.008
DBP§, mm Hg	71 ± 13	74 ± 13	71 ± 14	72 ± 12	64 ± 11	0.02
% ACEI||/ARB#	81	76	78	92	78	0.53
% BB**	88	76	85	100	91	0.04
LVEF entry	0.34 ± 0.10	0.33 ± 0.08	0.36 ± 0.10	0.37 ± 0.10	0.31 ± 0.10	0.55
LVEF 6 months	0.51 ± 0.11	0.50 ± 0.11	0.55 ± 0.07	0.54 ± 0.09	0.42 ± 0.13	0.10
LVEF 12 months	0.53 ± 0.10	0.52 ± 0.10	0.56 ± 0.06	0.56 ± 0.07	0.46 ± 0.15	0.15
LVEDD†† entry, cm	5.5 ± 0.07	5.7 ± 0.07	5.5 ± 0.06	5.6 ± 0.06	5.7 ± 0.08	0.66
% Recovered	72	71	81	83	47	0.17
Relaxin-2, pg/ml	29 ± 110	97 ± 203	10 ± 31	4 ± 2	5± 7	0.004
Prolactin, ng/ml	55 ± 64	114 ± 84	42 ± 48	28 ± 21	32 ± 41	0.000001
sFlt1‡‡, pg/ml	240 ± 402	539 ± 621	99 ± 52	121 ± 130	206 ± 373	0.003
VEGF§§, pg/ml	388 ± 319	454 ± 329	346 ± 256	328 ± 281	434 ± 411	0.73

^*NYHA = New York Heart Association;

^†HR=heart rate;

^‡SBP=systolic blood pressure;

^§DBP diastolic blood pressure;

^||ACEI= angiotensin-converting enzyme inhibitor;

^#ARB=angiotensin receptor blocker;

^**BB=beta blocker,

^††LVEDD= left ventricular end-diastolic diameter;

^‡‡sFlt1=soluble fms like tyrosine kinase 1;

^§§VEGF=vascular endothelial growth factor. P-value is for linear ANOVA.

Figure 1. Biomarker levels by days post-partum (quartiles).

A. Relaxin-2 levels (pg/ml) were significantly higher in women presenting in the first quartile (0 to 11 days) compared to subjects presenting in the latter three (12 to 95 days). (p=0.0043). B. Prolactin levels (ng/ml) were significantly higher in women presenting in the first quartile compared to subjects presenting in the latter three (p<0.00001). C. sFlt1 levels pg/ml were significantly higher in women presenting in the first quartile compared to subjects presenting in the latter three (p<0.003). D. VEGF levels (pg/ml) were not significantly different by days post-partum (p=0.73). Boxplots: box represents the interquartile range from1st to 3rd quartile. Median represented by a thick black line across the interquartile range. Error bars represent 1.5 times the interquartile range.

Myocardial recovery and remodeling

For the entire cohort (n=98), GLM analysis by tertiles of relaxin-2 level (lowest <2.5 pg/ml, intermediate 2.5 to 6.4 pg/ml, and highest >6.4 pg/ml) demonstrated that higher relaxin-2 levels were associated with a higher LVEF at 2 months (p=0.01, Figure 2A, Table 2). Analysis of heart rate (HR) and blood pressure (BP) by relaxin-2 tertiles revealed no significant differences either at entry (mean HR in low, intermediate and high relaxin tertiles: 83+17, 87+12, 87+19, p =0.38; systolic BP: 110+15, 111+18, 114+18, p=0.35; diastolic BP: 67+11, 71+14,73+13, p=0.10) or at 2 months (mean HR in low, intermediate, and high relaxin tertiles: 78+17, 78+11, 71+12, p =0.07; systolic BP: 107+16, 107+14, 106+13, p=0.88; diastolic BP: 68+9, 67+12, 65+10, p=0.22).

Figure 2. LVEF over time by tertiles of relaxin-2 level at entry.

A. Entire cohort (n=98). White bars=lowest tertile, gray bars= intermediate tertile, and red bars=highest tertile. Early myocardial recovery (LVEF at 2 months) best in the highest relaxin tertile (p=0.01) B. Subjects enrolled in the first quartile of days post-partum (0–11 days, n=25): White bars=lowest tertile, gray bars=intermediate tertile, red bars=highest tertile. Early myocardial recovery (LVEF at 2 months) again greatest in the highest relaxin tertile (p=0.02)

Table 2.

LVEF over time by tertiles of relaxin-2 levels at entry for entire cohort and 1^st quartile

	Low	Intermediate	High	P value
Entire cohort, (n=98)
LVEF (early)	0.33 ± 0.11	0.34 ± 0.08	0.37 ± 0.08	0.17
LVEF (2 mo)	0.39 ± 0.14	0.44 ± 0.10	0.47 ± 0.10	0.01
LVEF (6 mo)	0.49 ± 0.13	0.51 ± 0.09	0.53 ± 0.09	0.18
LVEF (12 mo)	0.51 ± 0.12	0.56 ± 0.07	0.54 ± 0.09	0.25
First Quartile (n= 25)
LVEF (early)	0.32 ± 0.07	0.31 ± 0.08	0.38 ± 0.08	0.15
LVEF (2 mo)	0.38 ± 0.11	0.45 ± 0.09	0.53 ± 0.10	0.02
LVEF (6 mo)	0.44 ± 0.14	0.52 ± 0.07	0.54 ± 0.12	0.09
LVEF (12 mo)	0.47 ± 0.14	0.53 ± 0.09	0.55 ± 0.08	0.19

No significant differences were apparent by relaxin tertiles in medical therapy. At entry, 81% of subjects were on an angiotensin converting enzyme (ACE) inhibitor. 61% were on lisinopril with no differences in mean dose by relaxin tertile (lisinopril daily dose at entry by low, intermediate, high relaxin tertile: 12+10 mg, 10+11 mg, 11+15 mg, p =0.79). At two months, 86% were on an ACE inhibitor, including 64% on lisinopril. There remained no differences in dose by relaxin tertile (low, intermediate, high relaxin tertiles: 14+10 mg, 11+11 mg, 12+16 mg, p =0.66). At entry, 88% were on a beta blocker. 68% were on carvedilol with no significant differences in dose by relaxin tertile (carvedilol daily dose at entry by low, intermediate, high relaxin tertiles: 13+6 mg, 16+12 mg, 18+16 mg, p =0.17). At two months, 94% were on a beta blocker, including 71% on carvedilol. There were no significant differences in dose at 2 months by relaxin tertile (low, intermediate, and high relaxin tertiles: 17+12mg, 18+11 mg, 25+19mg, p =0.09).

Given that relaxin-2 levels were predominantly elevated in subjects presenting in the first quartile (0 to 11 days, n=25), we repeated the previous analysis specifically in this subset presenting early post-partum. GLM analysis comparing 2 month LVEF by tertiles of relaxin-2 levels (lowest <7.0 pg/ml, intermediate 7.0 to 22.0 pg/ml, highest >22 pg/ml) demonstrated that the association between relaxin-2 and 2 month LVEF was more pronounced and remained significant (p=0.02, Figure 2B).

In the entire cohort, higher relaxin-2 levels were also associated with smaller LV systolic diameter (LVSD, p=0.006) at presentation with a trend toward lower LVEDD (p=0.06), however this was not evident in the subset presenting early [LVSD (p=0.30) and LVEDD (p=1.0)]. Comparison of mean LVEF over time by tertiles of prolactin, sFlt1 and VEGF levels did not demonstrate any relationship in either the overall IPAC cohort or in the quartile of subjects presenting early.

Symptoms and event free survival

At the time of enrollment, sFlt1 levels were significantly higher in women with more severe heart failure based on NYHA functional class (p=0.01, Figure 3). Six subjects either died or required LVAD support during the first year postpartum, and mean sFlt1 levels were higher in these subjects (592 ± 595 vs. 223 ± 393 pg/ml, p=0.03). Event free survival was significantly poorer for subjects in the highest sFlt1 tertile (p=0.004, Figure 4). In contrast relaxin-2, prolactin and VEGF were not associated with NYHA class or event free survival.

Figure 3. Soluble Flt1 levels by NYHA class.

Boxplots with red box representing the interquartile range from 1st to 3rd quartile. Median represented by a thick black line across the interquartile range. Error bars represent 1.5 times the interquartile range. Higher progressive sFlt1 levels with increasing NYHA class (p=0.01)

Figure 4. Event Free survival by sFlt1 tertiles.

Event free survival was defined as free of death, cardiac transplantation, or LVAD implantation. Kaplan Meier log rank analysis comparing subjects in the highest tertile of soluble Flt1 levels with subjects in the lower two tertiles. Poorer event free survival was evident for subjects with higher sFlt1 level (p=0.004)

DISCUSSION

Recent laboratory data suggest that vascular biomarkers may play a role in the development and progression of PPCM. In a well-defined cohort of women with newly diagnosed PPCM, we found that higher relaxin-2 levels were associated with more rapid myocardial recovery as evidenced by significantly higher LVEF at 2 months post-partum. Higher sFlt1 levels were associated with more severe functional limitation and major adverse clinical events. This is the first report of an association of relaxin and sFlt1 with outcomes in PPCM.

The presence of higher levels of relaxin-2 in patients with less LV remodeling and greater likelihood of recovery at 2 months suggests that it may play a cardioprotective role in PPCM. Relaxin is a naturally occurring human peptide that exerts systemic vasodilatory effects through stimulation of endothelin B receptors on vascular endothelial cells. Additional beneficial effects include sodium and water excretion, reduced inflammation, and cardioprotection. Given the known physiologic activities of relaxin, possible mechanisms of benefit in PPCM include lower vascular resistance, decreased inflammation, increased angiogenesis, and decreased fibrosis. These findings raise the possibility of using recombinant human relaxin-2 (serelaxin) as a therapeutic agent to facilitate recovery in PPCM. Serelaxin has been shown to improve dyspnea in patients with acute heart failure (22) and is currently being tested in a phase 3 clinical study. Our data are observational in nature, and it is possible that relaxin-2 is a marker rather than a mediator of LV recovery. In this scenario, higher levels of relaxin-2 may indicate a good prognosis in women with PPCM, while lower levels may direct closer follow-up.

Higher levels of sFlt1 in patients with more advanced heart failure symptoms and higher likelihood of progression to death or LVAD support the proposed role of sFtl1 in the pathogenesis of PPCM as well as the potential for therapy directed at this pathway. sFlt1 is an antiangiogenic factor released from the placenta during the peripartum phase. Translational work from Patten et al. (14) has shown that sFlt1 and other VEGF inhibitors combine to create an anti-angiogenic environment that impairs both systolic and diastolic function. These data also help to explain why pre-eclampsia and multiple gestations have been observed to be risk factors for the development of PPCM (27, 28). The source of sFlt1 in PPCM subjects presenting late is not known, but placental remnants and other circulating cells have been postulated (29,30). Our findings suggest a potential role for sFlt1 in risk stratification for patients presenting with PPCM. The number of events in our study was small, however, and larger cohorts of PPCM will be needed to define the independent prognostic power of sFlt1 as well as the time-dependent nature of this circulating factor.

The findings of both relaxin-2 and sFlt1 lend credence to the concept of PPCM as a disorder, at least in part, of impaired angiogenesis. The discordance of demonstrated impact of relaxin-2 and sFlt1 on LV remodeling and recovery and clinical heart failure events is interesting. Given that the vasodilatory and proangiogenic effects of relaxin-2 are in part mediated by VEGF and that sFlt1 inhibits VEGF activity, this points to a common pathway of imbalance in angiogenesis driving PPCM and the associated clinical outcomes. The balance of these cardioprotective and pathologic mediators may be crucial in determining occurrence of PPCM and clinical outcomes for these patients. Further study may aid in developing a prognostic framework utilizing these markers.

There was significant variability in the time to presentation within the IPAC cohort, which may confound the results based on referral bias. Analysis of subjects enrolled in the first quartile based on days postpartum was chosen as a way to address this issue. In addition, within the cohort, there were patients that had significant outlying values for sFlt1 and VEGF, which could cloud detectable associations with clinical outcomes.

In this cohort, we observed no relationship between prolactin and LV recovery or adverse clinical events. While therapeutic intervention with bromocriptine, an inhibitor of prolactin release, has been reported to improve clinical outcomes for PPCM in a small pilot investigation (31), a large non-randomized German registry of 115 women with PPCM (in which 67% were treated with bromocriptine) reported no differences in the percentage of women with full recovery based on bromocriptine therapy (32). A randomized trial currently underway should help determine the role of bromocriptine therapy (33). Although as expected prolactin levels tended to be higher in the 15% of this cohort who were breast feeding at the time of enrollment, no significant difference in LVEF was observed during follow up (7). The 16 kDa prolactin cleavage product was not measured in the current study, and we cannot draw conclusions about its potential role in either the pathogenesis of PPCM or subsequent myocardial recovery.

CONCLUSIONS

In the IPAC cohort, higher relaxin-2 levels, particularly when obtained early post-partum, were associated with early myocardial recovery and a higher LVEF at 2 months. In contrast, elevated sFlt1 levels associated with higher NYHA class and a greater risk of major adverse events. These findings support the concept that PPCM is, at least in part, a disorder of vascular homeostasis and suggest that these biomarkers may not only assist in the determination of prognosis in PPCM, but also serve as targets for future therapy.

CLINICAL PERSPECTIVES.

PPCM is a cardiomyopathy with unknown etiology and diverse clinical outcomes. Recently, vascular biomarkers have been proposed to play a role in the development and progression of PPCM. In this cohort, elevated relaxin-2 was associated with early myocardial recovery and elevated sFlt1 with adverse clinical outcomes. These findings support the idea that vascular homeostasis may play a role in PPCM. These mediators may provide prognostic information and future targets for therapy in PPCM.

TRANSLATIONAL OUTLOOK.

Support for a vascular component to the pathophysiology of PPCM highlights the need for further study of vascular biomarkers in this disorder. Whether these agents can serve as prognostic indicators in patients with PPCM needs to be determined. They may also serve as potential therapeutic targets in PPCM.

Abbreviations

ACE

angiotensin converting enzyme

BP

blood pressure

HR

heart rate

LV

left ventricular

LVAD

left ventricular assist device

LVEDD

Left ventricular end-diastolic diameter

LVEF

left ventricular ejection fraction

LVSD

left ventricular systolic diameter

NYHA

New York Heart Association

PPCM

peripartum cardiomyopathy

sFlt1

soluble fms-like tyrosine kinase 1

VEGF

vascular endothelial growth factor

APPENDIX

IPAC Investigators

University of Pittsburgh Medical Center (10) Dennis M McNamara, MD; James D. Fett, MD; Jessica Pisarcik, RN, BSN; Charles McTiernan, PhD; Karen Hanley-Yanez, BS; John Gorcsan III, MD; Erik Schelbert, MD. Intermountain Medical Center (8) Rami Alharethi, MD; Kismet Rasmusson, CRNP; Kim Brunisholz; Amy Butler, BS, CCRP; Deborah Budge; A.G. Kfoury, MD; Benjamin Horne, PhD; Joe Tuinei; Heather Brown. Vanderbilt University (7) Julie Damp, MD; Allen J. Naftilan, MD; Jill Russell, RN, MSN; Darla Freehardt, LPN, BS, CCRP. Cleveland Clinic (7) Eileen Hsich, MD; Cynthia Oblak, CCRC. Washington University, St. Louis (6) Greg Ewald, MD; Donna Whitehead, RN; Jean Flanagan, RN; Anne Platts. University of Southern California (6) Uri Elkayam, MD; Jorge Caro, MPH; Stephanie Mullin, RN. Brigham and Women’s Hospital (5) Michael M. Givertz, MD; M. Susan Anello, RN, BS. University of Kentucky (5) Navin Rajagopalan, MD; David Booth, MD; Tiffany Sandlin, RN; Wendy Wijesiri, RN. Mayo Clinic (4) Leslie T. Cooper, MD; Lori A. Blauwet, MD; Joann Brunner, RN; Mary Phelps; Ruth Kempf. Louisiana State University (4) Kalgi Modi, MD; Tracy Norwood. University of Illinois (4) Joan Briller, MD; Decebal Sorin Griza, MD. Duke University (4) G. Michael Felker, MD; Robb Kociol, MD; Patricia Adams, RN. Wake Forest (4) Gretchen Wells, MD; Vinay Thohan, MD; Deborah Wesley-Farrington, RN, BSN, CCRC, CCA; Sandra Soots, RN, CCRC. Jewish General (3) Richard Sheppard, MD; Caroline Michel, MD; Nathalie Lapointe, RN, PhD; Heather Nathaniel. University of Calgary (3) Angela Kealey, MD. Massachusetts General (2) Marc Semigran, MD; Maureen Daher, RN. Penn State Milton S. Hershey Medical Center (2) John Boehmer, MD; David Silber, MD; Eric Popjes, MD; Patricia Frey, RN; Todd Nicklas, RN. University of Rochester (2) Jeffrey Alexis, MD; Lori Caufield, RN, BSN, CCRC. Georgia Health Sciences University (2) John W. Thornton III, MD; Mindy Gentry, MD; Vincent J.B. Robinson, MBBS; Gyanendra K. Sharma, MD; Joan Holloway, BS; Maria Powell, LPN, CCRC. University of Texas, Southwestern (2) David Markham, MD; Mark Drazner, MD; Lynn Fernandez, RN. Newark Beth Israel Medical Center (2) Mark Zucker, MD; David A. Baran, MD; Martin L. Gimovsky, MD; Natalia Hochbaum, MD; Bharati Patel, RN, CCRC; Laura Adams, RN, BSN. University of Maryland (2) Gautam Ramani, MD; Stephen Gottlieb, MD; Shawn Robinson, MD; Stacy Fisher, MD; Joanne Marshall, BSN, MS. Columbia University (2) Jennifer Haythe, MD; Donna Mancini, MD; Rachel Bijou, MD; Maryjane Farr, MD; Marybeth Marks, Henry Arango. Baylor College (2) Biykem Bozkurt, MD, PhD, FACC, FAHA; Mariana Bolos. Thomas Jefferson (1) Paul Mather, MD; Sharon Rubin, MD; Raphael Bonita, MD; Susan Eberwine, RN. Stony Brook University Medical Center (1) Hal Skopicki, MD, PhD; Kathleen Stergiopoulos, MD; Ellen McCathy-Santoro, MD; Jennifer Intravaia, RN, CCRCII; Elizabeth Maas. Morristown Hospital (0) Jordan Safirstein, MD; Audrey Kleet, RN, MS, ACNP-BC, CCRN, CCTC; Nancy Martinez, RN; Christine Corpoin, RN; Donna Hesari, RN. University of Miami (0) Sandra Chaparro, MD; Laura J. Hudson, MA, MPH, CCRC. Harper University Hospital (0) Jalal K. Ghali, MD; Zora Injic, RN, BSc, MSA. Johns Hopkins Hospital (0) Ilan S. Wittstein, MD.