Year: 2008
Type: dissertation
Abstract: ABSTRACT \nIntroduction: Peripartum cardiomyopathy (PPCM) is defined as a disorder of unknown aetiology that \noccurs between one month antepartum and five months postpartum in women without pre-existing heart \ndisease. While the incidence of PPCM has been reported between 1: 2392 and 15000 live births in the USA, \nthe disease is ubiquitous on the African continent with an incidence ranging from 1: 100 to 1: 1000 \ndeliveries. The mortality rate ranges between 15 and 40.7%, while 23 to 54% of patients recover completely. \nAim of this thesis was to describe the clinical profile of 100 PPCM patients, identify predictors of negative \noutcome, analyze differences in kinetics of cardiac function biomarkers, pro-inflammatory cytokines, \nmarkers of re-modeling and prolactin in cardiac function improvers versus non-improvers and investigate a \npossible autoimmune component in the pathogenesis of PPCM. \nMethods: We conducted a single centre, prospective study of 100 newly diagnosed patients meeting \ndiagnostic criteria for PPCM. All patients received standard anti-failure therapy with diuretics (furosemide, \naldactone), the β-blocker carvedilol, ACE-inhibitor perindopril and digoxin if indicated. Clinical assessment, \n2-dimensional echocardiographic studies and blood analysis were systematically performed at time of \npresentation, after six and twelve months of therapy. \nFindings: Fifteen patients died within the follow-up period of six months and eight were not available for \nfull follow-up since they moved to remote areas. Patients who completed six months of treatment showed a \nsignificant reduction of heart rate, left ventricular dimensions and significant improvement in \nscintigraphically and echocardiographically derived values for left ventricular ejection fraction (p< 0.0001) \nand NYHA functional class (p< 0.001). However, normalization of LVEF (>50%) was only observed in 18 \n(23%) of the patients. Baseline plasma levels of Fas/Apo-1 (OR = 3.56, CI 95% = 1.35–9.42) and NYHA FC \n(OR = 2.67, CI 95% = 1.04–6.83) were independent predictors of death.extra-cellular loop (RAESDE and DEARRCY), while those from DCMO patients bind to epitopes on the \nfirst (30%) and second extra-cellular loop (ARRCYND and PKCCDF). The β1-adrenoreceptor agonist-like \nantibodies identified in PPCM patients are part of the IgG2 and IgG3 subclass, while those from DCMO \npatients belong to the IgG2 subclass. Furthermore we demonstrated that β1-adrenoreceptor antibodies in \nserum of PPCM patients prevented desensitization of the receptor. The β1-adrenoreceptor antibodies in \nserum of PPCM patients were not detectable in serum of non PPCM peripartum controls and are different \nfrom those found in patients with DCMO, suggesting that PPCM forms a distinct disease entity. We \ndemonstrated a positive correlation between the activity of the β1-adrenoreceptor antibodies and serum \nexpression levels of the marker of cardiac function NT-proBNP from baseline to twelve months (rs=0.58, 2- \ntailed P=0.0228), 95% CI (0.10 to 0.84). \nInvestigating the cause for high prolactin expression levels in serum of PPCM patients, we identified a \nSTAT3 deficit in a PPCM mouse model. Significantly increased levels of cathepsin D cause the cleavage of the physiological 23-kDa form of prolactin into a 16-kDa form in PPCM patients, but not in non-PPCM \nperipartum controls. This initiated another clinical study, investigating the effect of the prolactin-inhibitor \nbromocriptine in addition to standard heart failure therapy in known PPCM patients, presenting with a \nsubsequent pregnancy. Comparison of clinical and echocardiographic data of these patients to others on \nstandard heart failure therapy demonstrated preservation or improvement of left ventricular dimensions and \nsystolic function as well as NYHA FC. \nConclusion: \nWhile a wide range of parameters, reflecting cardiac dysfunction and pro-inflammatory immune activation, \nwere elevated in all PPCM patients at time of first presentation, indicating their involvement in the initiation \nof the disease, we found significant differences over time between cardiac function improvers and nonimprovers \nfor ΔIFN-gamma (P=0.0181) serum levels, suggesting their role in disease progression. \nHeightened IFN-gamma expression could indicate an ongoing T-cell mediated autoimmune response and an \ninsult to the cardiac muscle, resulting in fibrosis and inability to improve left ventricular systolic function. \nProlactin represents a stimulatory link between the neuroendocrine and immune systems, promoting proinflammatory \nimmune responses. Interestingly, we found significantly higher (P<0.0001) serum prolactin \nlevels in PPCM patients at time of first presentation than in peripartum controls, suggesting the hormone’s \nrole during the initial acute phase of PPCM. Several authors have described the induction of IFN-gamma by \nprolactin. Disease progression and the ongoing autoimmune insult by beta1-adrenergic autoantibodies \nappear to be driven by IFN-gamma. This pro-inflammatory cytokine remained high in PPCM nonimprovers, \ndecreased in improvers, was previously implicated in the development of autoimmune disease \nand its suppression leads to desensitization of β-adrenoreceptors. Together with the β1-adrenoreceptor \nautoantibodies that we have identified in PPCM patients and their demonstrated property to also prevent \ndesensitization of β1-adrenoreceptors, patients experience an adrenergic overdrive, leading to cardiac \nmyocyte insult. \n10 \nWhile the pathogenesis of PPCM appears to be multifactorial, our task as scientists remains to find out, how \nthe monolith was erected. Specifically, it appears promising to investigate the effects of bromocriptine in \naddition to standard heart failure therapy in a randomised, double-blinded clinical study. Although one could \nargue that prolactin regulated expression of IFN-gamma and other cytokines may explain the gender-specific \ndifferences in autoimmunity, it has been shown that elevated serum prolactin concentrations are associated \nwith accelerated autoimmune disease in both female and male mice. Possibly, prolactin does not only play a \nrole in the pathogenesis of PPCM, but also in other forms of cardiomyopathy, affecting males and females \nalike. It would be interesting to study prolactin serum expression levels in male and female patients with \nidiopathic DCMO. Clearly, further studies into the unfolding pathogenesis of PPCM are indicated.
Author: Olaf Förster
Language: Finnish
Subfield: Cardiology and Cardiovascular Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2106877752