High density lipoprotein cholesterol (HDL) and its component sphingosine-1-phosphate (S1P) protect against myocardial infarction. Recently, the SAFE (survivor activating factor enhancement) pathway, involving tumour necrosis factor (TNF) and the transcription factor signal transducer and activator of transcription 3 (STAT-3), has been identified as a key signalling pathway in cardioprotection, although the end effector remains unclear.

Includes bibliographical references (leaves 52-56). / The expanding application of cardiac resynchronization (CRT) and implantable cardioverter-defibrillator therapy (lCD) to include patients with congenital heart disease requires careful evaluation of selection criteria and unconventional adaptive strategies to ensure clinical efficacy. A single centre prospective analysis of adults post atrial redirection surgery (Mustard operation) for dextro-transposition of the great arteries (d-TGA) presenting with systemic right ventricular (sRV) dysfunction and at risk of sudden cardiac death (SCD). All patients ( mean age 25 years, range 18-35) with varying functional disability{New York Heart Association (NYHA) II-III} receiving ICDs ± concomitant CRT were evaluated. Total follow-up period was 24 months. A patient individualized approach was used for device implantation. Endocardial, epicardial and transthoracic defibrillation strategies were examined in 5 consecutive cases. A hybridized form of CRT was employed in two patients. Only one patient demonstrated response to therapy while the other deteriorated during biventricular pacing (BVP). This prompted a novel approach to CRT using noncontact mapping (NCM) and acute intra-arterial blood pressure response to guide endocardialsRV lead placement in a single patient. The ejection fraction increased from 23 -33% within 1week post procedure and clinical improvement was sustained after 6-months follow-up. Application of CRT II CD therapy to patients with sRV dysfunction requires individualized and adaptive strategies to overcome anatomical constraints. This study represents a chronological and evolutionary account of these measures.

Includes bibliographical references. / The treatment and outcome myocardial infarction has been revolutionised by the demonstration that thrombolytic grugs can open the infarct-related arterty, salvage ischaemic myocardium, preserve left ventricular function and save lives. However, thrombolytic drugs are not uniformly effective in securing or maintaining patency of the infarct-related artery.

Includes bibliographical references.

In the light of studies which show the upregulation of VEGF in contractile cells subjected to cyclic stretch and the profound effects which cyclic stretch has been shown to have on the release of other cytokines by SMC, this study investigates the role which cyclic stretch might play in VEGF expression by SMC in a compliant environment. Furthermore, following observations of receptor phosphorylation in response to cyclic stretch in vascular cells, the effect of cyclic strain on the KDR-mediated endothelial response to locally-released VEGF was also investigated. Low passage number bovine aortic SMC and EC were plated on collagen-coated elastomer plates and subjected to 10% repetitive strain at 1 Hz. The mRNA expression of VEGF in SMC and the phosphorylation of KDR on EC were determined by northern blotting and western blotting respectively. The biological activity on EC and levels of VEGF secreted into the medium by SMC under cyclic stretch were investigated using a migration assay and ELISA respectively. Cyclic stretch was found to cause a 3.3 (±1.5 p < 0.005) fold increase in VEGF mRNA levels over unstretched controls at 4 hours. This biomechanically-induced expression was found to drop slightly by 24 hours and to be approximately equivalent to expression induced by the cytokine bFGF over the same time course. These results correlated with an increase in VEGF levels in media from stretched SMC capable of inducing migration of EC by 1.6 fold although additional EC chemotactic factors appear to be released by stretch. Furthermore, although the levels of KDR remained constant under cyclic stretch, average KDR phosphorylation was found to increase weakly over time due to cyclic stretch. These results show that cyclic stretch affects the VEGF communication between SMC and EC at both the level of VEGF expression by SMC and at the level of VEGF recognition by the KDR receptor on EC. It is possible that through the nitric oxide (NO) pathway, VEGF release may alleviate abnormally high levels of cyclic strain. It is hoped that a better understanding of the role of VEGF communication between stretched SMC and EC will enable the design of a graft in which the level of compliance encourages SMC to maintain a functional endothelium. Following this it is hoped that the low levels of SMC and pericytes invading the graft, pacified by endothelial cell mediation, will not result in intimal hyperplasia but rather play a role in microvessel maintenance and more complete healing.

Background: Atrial fibrillation (AF) is the most common arrhythmia and may be complicated by embolic stroke. It is also associated with a significant risk of heart failure and mortality. The burden of rheumatic heart disease remains great in the developing world. The prevalence of AF in those with rheumatic heart disease is in the order of 20% with a resultant 17-fold increased risk of embolic stroke. Over time, many other risk factors for stroke in the AF population have been described. Stroke risk stratification tools such as the CHADS₂ (Congestive heart failure, hypertension, age of 75 or older, diabetes mellitus or stroke/TIA) and CHA₂DS₂VASc (with the addition of a second age category, female gender, and peripheral artery disease) scores have been developed. These are used to assess the need for anticoagulation and have been well validated. These scores have traditionally excluded those patients with valvular AF. Valvular AF has not been studied extensively in the contemporary era. Oral anticoagulation had previously been advised in all patients with valvular AF. Little is known however about outcomes for stroke and mortality in this cohort of patients. Furthermore, the utilization of the CHADS₂ and CHA₂DS₂VASc scores may provide incremental benefit in prognostication and resultantly, both more diligent prescription of anticoagulation and improved outcomes. Objectives: The objectives of this study were as follows - 1. To determine the prevalence of AF in the Global Rheumatic Heart Disease Registry (the REMEDY study) and in the Groote Schuur Hospital (GSH) cohort. 2. To assess the demographic, social and clinical characteristics of patients with AF in the REMEDY study and in the GSH cohort. 3. To assess the frequency of CHADS₂ and CHA₂DS₂VASc risk factors in the GSH cohort and to calculate a CHADS₂ and CHA₂DS₂VASc score on each of the patients with AF. 4. To establish whether CHADS₂ and CHA₂DS₂VASc scores further increase the risk of stroke and death in this cohort of patients with valvular AF. Methods: This is a substudy of the Global Rheumatic Heart Disease Registry (the REMEDY study). We assessed those with AF from the entire cohort for prevalence and outcome data. Patients with ECG or Holter proven AF from the GSH cohort were further risk stratified using the CHADS₂ and CHA₂DS₂Vasc scores. Clinical data was obtained from folder reviews and telephonic interviews. The CHADS₂ and CHA₂DS₂Vasc scores for each patient in the GSH cohort were calculated. Patients were followed up for 2 years and information pertaining to death and stroke were obtained from folder reviews. These were then correlated with the CHADS₂ and CHA₂DS₂Vasc scores. Results: A total of 2624 REMEDY patients were analysed. Of these, 22% in the total cohort (586 of 2684 patients) and 38.2% in the GSH cohort (187 of 489 patients) had AF. These patients were older (35 years vs. 25 years, p<0.0001), more likely to be female (73.1% vs. 65.6%, p=0.001) and more frequently had a history of congestive heart disease (41.0% vs. 33.3%, p=0.001) when compared to those in sinus rhythm. They also had significantly more strokes (13.8% vs. 5%, p<0.0001) and a poorer NYHA class (NYHA III& IV 30.8% vs. 25.2%, p=0.002). The cohort with AF had more severely impaired left ventricular (LV) function compared to those in sinus rhythm (Ejection fraction (EF) 57% vs. 61%. P<0.0001). The presence of a larger left atrial (LA) size, spontaneous echo contrast and LA thrombus was much greater in the AF cohort. Of those patients in AF, only 68% had received a prescription for warfarin. The GSH cohort was risk stratified using the CHADS₂ and CHA₂DS₂VASc scores. Twenty-three percent of patients had a CHADS₂ score of 0 and 27.7% of 1. When the same cohort was scored using the CHA₂DS₂VASc score, only 5.4% had a score of 0; this difference was mainly driven by the additional category of female gender. The patients in our cohort were young (median age 28 years) and had few comorbidities. Despite this, patients with AF did significantly worse than those in sinus rhythm, with a stroke rate of 4.6% and a mortality rate of 13.1% observed at 2 years (compared to a 1.5% stroke rate and 5.5% mortality rate for those in sinus rhythm). The presence of any additional comorbidities significantly reduced survival in both the short and long term. Greater CHA₂DS₂VASc score categories (CHA₂DS₂VASc 1 and CHA₂DS₂VASc 2 or more) conferred an incrementally higher risk of death. Conclusion: In a contemporary cohort of patients with rheumatic heart disease, AF is common with a prevalence of 22-39%. These patients were older and exhibited features of more advanced disease both clinically and on echo, compared to their sinus rhythm counterparts. The mortality and stroke rates in the AF group were high despite the relatively young age of this cohort. Mortality and stroke increased significantly and incrementally with each greater CHA₂DS₂VASc score category. Given the differences in chronicity between RHD in the developed world (i.e., disease of older people) and RHD in developing countries (i.e., disease of the young), these results cannot be extrapolated to those living in the first world.

Background Prosthetic valve infective endocarditis (PVE) is associated with high morbidity and mortality. The prevalence of PVE in local retrospective studies ranges between 13% and 16%. However, the clinical patient profile and outcomes remains unknown. Methods We performed a prospective observational study of patients presenting or referred to Groote Schuur Hospital with definitive or probably infective endocarditis based on the 2015 European Society of Cardiology (ESC) infective endocarditis diagnostic criteria. Consenting adult patients who met inclusion criteria were enrolled into the Groote Schuur Hospital Infective Endocarditis Registry which was approved by the University of Cape Town Human Research Ethics. The current study is an analysis of the cohort of patients who were enrolled between 01/01/2017 to 31/12/2019. The primary objective of this study was to define the clinical profile and outcomes of patients with PVE. The secondary objective aimed to compare the clinical profile and outcomes of PVE patients with those of native valve endocarditis patients (NVE). Results During the study period a total of 135 patients received a diagnosis of possible and definitive infective endocarditis (IE). Of these, 18 patients had PVE and 117 patients NVE. Therefore, PVE accounted for 13.3% of the overall IE cohort. PVE patients had mean (Standard Deviation) age of 39.1 (14.6) years, 56.6% were male. PVE occurred within one year of valve surgery in 50% and the Duke's modified diagnostic criteria for definitive IE was met in 94.4% of the PVE cohort. Prosthetic valves in the aortic position were affected in isolation or in combination with prostheses in the mitral area in 66.7%. Further, tissue prosthetic valves were affected in 61.1% of the PVE cases. 55.6% of the PVE cases were health care associated. On transthoracic echocardiography, vegetations (61.1%), prosthetic valve regurgitation (44.4%) and abscess (22.2%) were discovered. Staphylococcus species and streptococcus species accounted for 38.8% and 22.2% of PVE cases, respectively. 27.8% cases were blood culture negative. Valve surgery was performed in 38.7% of the PVE patients. 55.6% of the PVE patients demised during the index hospitalisation. The secondary analysis indicated that the PVE patients were sicker, with a higher frequency of septic shock and heart block than the NVE patients, 22.2% vs 7% p= 0.02 and 27.8% vs 12% p =0.04 respectively. In addition, in hospital mortality was higher in PVE patients than NVE patients, 55.6% vs 31.6% p=0.04. Conclusion PVE is relatively uncommon in resource-limited settings and is associated with a high in hospital mortality. Staphylococcus and streptococcus species are the leading microbiological causes of PVE. The selected PVE patients that receive surgical treatment for endocarditis demonstrate better in-hospital survival than those who do not receive surgical treatment. This finding not only reaffirms the importance of surgery as treatment option for IE but further demonstrate the importance of the Heart team in selecting appropriate surgical candidates.

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