Transvenous or subcutaneous implantable cardioverter defibrillator: a review to aid decision-making.

The implantable cardioverter-defibrillator (ICD) is a proven treatment for preventing sudden cardiac death. Transvenous leads are associated with significant mortality and morbidity, and the subcutaneous ICD (S-ICD) addresses this. However, it is not without limitations, in particular the absence of anti-tachycardia pacing. The decision of which device is most suitable for an individual patient is often complex. Here, we review the relative merits and weaknesses of both the transvenous and S-ICD. We summarise the available evidence for each device in particular patient cohorts, namely: ischaemic and non-ischaemic cardiomyopathy, idiopathic ventricular fibrillation, Brugada syndrome, long QT syndrome, arrhythmogenic right ventricular cardiomyopathy, and hypertrophic cardiomyopathy.

Improving haemodynamic optimization of cardiac resynchronization therapy for heart failure.

OBJECTIVE: Optimization of cardiac resynchronization therapy using non-invasive haemodynamic parameters produces reliable optima when performed at high atrial paced heart rates. Here we investigate whether this is a result of increased heart rate or atrial pacing itself. APPROACH: Forty-three patients with cardiac resynchronization therapy underwent haemodynamic optimization of atrioventricular (AV) delay using non-invasive beat-to-beat systolic blood pressure in three states: rest (atrial-sensing, 66 ± 11 bpm), slow atrial pacing (73 ± 12 bpm), and fast atrial pacing (94 ± 10 bpm). A 20-patient subset underwent a fourth optimization, during exercise (80 ± 11 bpm). MAIN RESULTS: Intraclass correlation coefficient (ICC, quantifying information content mean ±SE) was 0.20 ± 0.02 for resting sensed optimization, 0.45 ± 0.03 for slow atrial pacing (p  < 0.0001 versus rest-sensed), and 0.52 ± 0.03 for fast atrial pacing (p  = 0.12 versus slow-paced). 78% of the increase in ICC, from sinus rhythm to fast atrial pacing, is achieved by simply atrially pacing just above sinus rate. Atrial pacing increased signal (blood pressure difference between best and worst AV delay) from 6.5 ± 0.6 mmHg at rest to 13.3 ± 1.1 mmHg during slow atrial pacing (p  < 0.0001) and 17.2 ± 1.3 mmHg during fast atrial pacing (p  = 0.003 versus slow atrial pacing). Atrial pacing reduced noise (average SD of systolic blood pressure measurements) from 4.9 ± 0.4 mmHg at rest to 4.1 ± 0.3 mmHg during slow atrial pacing (p  = 0.28). At faster atrial pacing the noise was 4.6 ± 0.3 mmHg (p  = 0.69 versus slow-paced, p  = 0.90 versus rest-sensed). In the exercise subgroup ICC was 0.14 ± 0.02 (p  = 0.97 versus rest-sensed). SIGNIFICANCE: Atrial pacing, rather than the increase in heart rate, contributes to ~80% of the observed information content improvement from sinus rhythm to fast atrial pacing. This is predominantly through increase in measured signal.

Pharmacological interventions for the prevention of contrast-induced acute kidney injury in high-risk adult patients undergoing coronary angiography: a systematic review and meta-analysis of randomised controlled trials.

Objective: Quantify the efficacy of strategies to prevent contrast-induced acute kidney injury (CI-AKI) in high-risk patients undergoing coronary angiography (CAG) with or without percutaneous coronary intervention (PCI). Background: CI-AKI remains a common problem. The renoprotective efficacy of existing pharmacological agents remains uncertain in high-risk populations. Methods: Systematic review and meta-analysis of randomised controlled trials (RCTs) to compare different strategies versus hydration in patients with chronic kidney disease (CKD) undergoing CAG±PCI. Primary outcome was incident CI-AKI. Fixed-effects meta-analyses estimated ORs, 95% CIs and heterogeneity. Results: Forty-eight RCTs were included. Seven pharmacological strategies were evaluated by multiple RCTs and 10 by one RCT each. These had varying risk of bias; >25% of trials were at high risk of performance bias. Five strategies significantly reduced the odds of CI-AKI: N-acetylcysteine (NAC) (27 trials, 5694 participants; OR=0.77, 95% CI 0.65 to 0.91, p=0.002, I2=36%), ascorbic acid (four trials, 759 participants; OR=0.59, 95% CI 0.39 to 0.89, p=0.01, I2=0%), statin (two trials, 3234 participants; OR=0.59, 95% CI 0.39 to 0.89, p=0.75, I2=0%), trimetazidine (two trials, 214 participants; OR=0.27, 95% CI 0.10 to 0.71, p=0.01, I2=0%) and nicorandil (two trials, 389 participants; OR=0.47, 95% CI 0.23 to 0.94, p=0.03, I2=52%). Theophylline had a similar, but non-significant, effect. A subgroup analysis found that the benefit of NAC was highest in patients requiring a high-contrast dose. Conclusions: Several drugs are renoprotective in patients with CKD undergoing CAG±PCI. The evidence is strongest for NAC. We recommend that NAC should be used when a high dose of contrast is anticipated. Trial registration number: PROSPERO registration CRD42014014704.Open Science Framework link: https://osf.io/vxg7d/?view_only=62bad0404b18405abd39ff2ead2575a8.