The cardiorenal continuum: a focus on iron deficiency, arrhythmia

Heart failure remains a leading cause of hospitalisation in the developed world. Comorbidities such as iron deficiency and chronic kidney disease (CKD) pose management challenges and have been proven to have prognostic impact. The link between cardiac and renal disease is complex and is now understood to begin before abnormalities in either system become manifest. This gradual transition from coexistence of risk factors to target organ damage and death is often referred to as the cardiorenal continuum. When cardiac and renal dysfunction co-exist, further challenges arise due to the high burden of cardiovascular risk factors that characterise these populations and the lack of a robust evidence base specific for these patients. Management can therefore be biased and sub optimal.This thesis focuses on two major comorbidities of heart failure- iron deficiency and chronic kidney disease, with the former being a common comorbidity to both pathologies. The first part of this thesis aims to understand the role of iron deficiency in acute heart failure, its prevalence and its potential links to inflammation and renal dysfunction. The second part of this thesis focuses on cardiorenal disease and aims to define arrhythmic burdens and incidence of sudden cardiac death in end stage kidney disease patients. This thesis also aims to establish the safety and feasibility of using evidence-based therapies in the presence of CVD and renal dysfunction and compares prescribing practices, complication rates and outcomes in those with and without significant CKD

Step by Step through the Years—High vs. Low Energy Lead Extraction Using Advanced Extraction Techniques

Background: Limited data is available about the outcome of TLE in patients with vs. without high energy leads in the last decade. Methods: This is an analysis of consecutive patients undergoing TLE at a high-volume TLE centre from 2001 to 2021 using the stepwise approach. Baseline characteristics, procedural details and outcome of patients with high energy lead (ICD group) vs. without high energy lead (non-ICD group) were compared. Results: Out of 667 extractions, 991 leads were extracted in 405 procedures (60.7%) in the ICD group and 439 leads in 262 procedures (39.3%) in the non-ICD group. ICD patients were significantly younger (median 67 vs. 74 years) and were significantly less often female (18.1% vs. 27.7%, p < 0.005 for both). Advanced extraction tools were used significantly more often in the ICD group (73.2% vs. 37.5%, p < 0.001), but there were no significant differences in the successful removal (98.8% vs. 99.2%) or complications (4.7% vs. 3.1%) between the groups (p > 0.2 for both). Discussion: Using the stepwise approach, overall procedural success was high and complication rate was low in a high-volume centre. In patients with a high energy lead, the TLE procedure was more complex, but outcome was similar to comparator patients

Monitoring of arrhythmia and sudden death in a hemodialysis population: The CRASH-ILR Study

<div><p>Introduction</p><p>It has been suggested that sudden cardiac death (SCD) contributes around 50% of cardiovascular and 27% of all-cause mortality in hemodialysis patients. The true burden of arrhythmias and arrhythmic deaths in this population, however, remains poorly characterised. Cardio Renal Arrhythmia Study in Hemodialysis (CRASH-ILR) is a prospective, implantable loop recorder single centre study of 30 established hemodialysis patients and one of the first to provide long-term ambulatory ECG monitoring.</p><p>Methods</p><p>30 patients (60% male) aged 68±12 years receiving hemodialysis for 45±40 months with varied etiology (diabetes 37%, hypertension 23%) and left ventricular ejection fraction (LVEF) 55±8% received a Reveal XT implantable loop recorder (Medtronic, USA) between August 2011 and October 2014. ECG data from loop recorders were transmitted at each hemodialysis session using a remote monitoring system. Primary outcome was SCD or implantation of a (tachy or bradyarrhythmia controlling) device and secondary outcome, the development of arrhythmia necessitating medical intervention.</p><p>Results</p><p>During 379,512 hours of continuous ECG monitoring (mean 12,648±9,024 hours/patient), there were 8 deaths—2 SCD and 6 due to generalised deterioration/sepsis. 5 (20%) patients had a primary outcome event (2 SCD, 3 pacemaker implantations for bradyarrhythmia). 10 (33%) patients reached an arrhythmic primary or secondary end point. Median event free survival for any arrhythmia was 2.6 years (95% confidence intervals 1.6–3.6 years).</p><p>Conclusions</p><p>The findings confirm the high mortality rate seen in hemodialysis populations and contrary to initial expectations, bradyarrhythmias emerged as a common and potentially significant arrhythmic event.</p></div

Overview of recruitment and outcomes.

<p>Overview of recruitment and outcomes.</p

Deaths in CRASH–ILR; a breakdown of findings.

<p>ESKD- end stage kidney disease, IHD- Ischaemic heart disease, CAD- coronary artery disease, MI- myocardial infarction, DM- Diabetes mellitus, HTN- hypertension, COPD-Chronic obstructive pulmonary disease, CHF-chronic heart failure, PEA- pulseless electrical activity, VT- ventricular tachycardia.</p

Number of transmissions per patient (patient 2 had ILR explant for infection soon after implant with no downloads prior, hence no data available.

<p>The device was misplaced following the death of patient 5 and the patient had not downloaded any data prior to death).</p

Baseline characteristics of study population.

<p>Key: SBP = systolic blood pressure, DBP = diastolic blood pressure, LVEF = left ventricular ejection fraction. Continuous variable data are expressed as mean ± standard deviation except * which indicates median (range). CHA₂DS₂-VASc- Risk factor scoring for AF stroke risk based on the presence of Congestive heart failure, Hypertension, Age, Diabetes mellitus, Stroke, Vascular disease, Sex/female. Covariates are available at an individual level on line.</p

Individual patient outcomes.

<p>Key: SCD- Sudden cardiac death, ILR- Implantable loop recorder, AF- Atrial fibrillation, PAF- paroxysmal atrial fibrillation, SVT- Supraventricular tachycardia, VT- Ventricular tachycardia, PPM- Pacemaker.</p