Device-detected sleep-disordered breathing predicts implantable defibrillator therapy in patients with heart failure

Funding Acknowledgements

Type of funding sources: None.

Background

Sleep-disordered breathing is highly prevalent in heart failure (HF) and it has been suggested as a risk factor for malignant ventricular arrhythmias. The Respiratory Disturbance Index (RDI) algorithm computed by select implantable cardioverter defibrillators (ICDs) can identify severe sleep apnea (SA).

Purpose

In the present analysis we evaluated the association between ICD-detected SA and the incidence of appropriate ICD therapy in patients with HF.

Methods

We enrolled 411 HF patients (age 69±10years, 77% male, ejection fraction 32±8%), implanted with an ICD endowed with an algorithm (ApneaScan, Boston Scientific) that calculates the RDI each night. In this analysis the weekly mean RDI value was considered. The endpoint was the first appropriate ICD shock. The median follow-up was 26 months [25th–75th percentile: 16-35].

Results

During follow-up, one or more ICD shocks were documented in 58 (14%) patients.

Patients with shocks were younger (66±13years versus 70±10years, p=0.038), and more frequently implanted for secondary prevention (21% versus 10%, p=0.026). The maximum RDI value calculated during the entire follow-up period did not differ between patients with and without shocks (55±15episodes/h versus 54±14episodes/h, p=0.539). However, the ICD-detected RDI showed a considerable variability during follow-up. The overall median of the weekly RDI was 33episodes/h [25th–75th percentile: 24-45]. Using a time-dependent Cox regression model, the continuously measured weekly mean RDI≥45episodes/h was independently associated with shock occurrence (HR:4.63, 95%CI:2.54-8.43, p<0.001), after correction for baseline confounders (age, secondary prevention).

Conclusions

In HF patients, patients were more likely to receive appropriate ICD shocks during periods of time when they exhibited more sleep-disordered breathing.

Implantable cardioverter defibrillator multisensor monitoring during home confinement caused by the covid-19 pandemic

Funding Acknowledgements

Type of funding sources: None.

Background

Utilization of remote monitoring platforms was recommended amidst the COVID-19 pandemic. The HeartLogic algorithm combines data from multiple implantable cardioverter defibrillator (ICD) sensors (first and third heart sounds, intrathoracic impedance, respirations, night heart rate, and patient activity) to provide integrated data that may allow for detection of early signs of worsening HF.

Purpose

We examined whether the HeartLogic platform may elucidate behavioral changes that impact HF decompensation, and the possible consequences of home confinement caused by the COVID-19 pandemic.

Methods

The Italian lockdown was imposed from March 8th to May 18th. On March 8th 2020, the HeartLogic feature was active in 349 ICD and cardiac resynchronization therapy ICD patients at 20 Italian centers. The period from January 1st to July 19th was divided in 3 phases: Pre-Lockdown (weeks 1-11), Lockdown (weeks 12-20), Post-Lockdown (weeks 21-29).

Results

Immediately after the implementation of stay at home orders (week 12) we observed a significant drop in median activity level (65min [36-103] in week 12 vs. 101min [61-140] in Pre-Lockdown; p < 0.001), while there was no difference in the other contributing sensors. The median composite HeartLogic index increased at the end of Lockdown (4.7 [1.3-10.2] in week 20 vs. 2.5 [0.7-7.0] in Pre-Lockdown; p = 0.019). The weekly rate of HeartLogic alerts was significantly higher during Lockdown (1.56 alerts/week/100pts, 95%CI:1.15-2.06; IRR = 1.71, p = 0.014) and Post-Lockdown (1.37 alerts/week/100pts, 95%CI:0.99-1.84; IRR = 1.50, p = 0.072) than that reported in Pre-Lockdown (0.91 alerts/week/100pts, 95%CI:0.64-1.27). However, the median duration of alert state and the maximum index value did not change among phases, as well as the proportion of alerts followed by clinical actions at the centers (Pre-Lockdown: 31%, Lockdown: 22%, Post-Lockdown: 28%), and the proportion of alerts fully managed remotely (i.e. no in-clinic visits) (Pre-Lockdown: 89%, Lockdown: 90%, Post-Lockdown: 88%).

Conclusions

The system was sensitive to the behavioral changes occurred during the lockdown, i.e. decrease in activity. However, the home confinement had no impact on the other sensors. The higher rate of HeartLogic alerts during lockdown and the increase in the median index after 8 weeks of home confinement suggest the worsening of the HF status, possibly explained by the behavioral changes. Nonetheless, the management of the HF detected events (actions performed and management strategy) was not impacted by the restrictions.

T cells and cytokines in atherogenesis

Recent findings suggest that inflammation plays a key role in atherosclerosis from the earliest stage of lesion initiation, to the ultimate complication of thrombosis. In patients who died because of acute coronary syndromes (ACS), coronary atherosclerotic plaques are characterized by the presence of macrophages, and to a lesser extent T-lymphocytes, at the immediate site of either plaque rupture or superficial erosion. The rupture-related inflammatory cells are activated, indicating ongoing inflammation. ACS patients are also characterized by activated circulating lymphocytes, monocytes and neutrophils, and by increased concentrations of proinflammatory cytokines and of the highly sensitive acute phase reactant C-reactive protein. Interestingly, an unusual subset of T cells, CD4+CD28null T cells, involved in vascular complication of rheumatoid arthritis because of their functional profile predisposing for vascular injury, are expanded in the peripheral blood and infiltrate the coronary lesions of ACS patients. The presence of activated T lymphocytes implies antigenic stimulation, but the nature of such antigen(s) remains to be investigated. Several autoantigens expressed in the atherosclerotic plaque, including oxidized LDL and heat shock proteins, and infectious agents are able to elicit an immune response. The inflammatory component is not localized to the ‘culprit’ plaque, but it is diffused to the entire coronary vascular bed, and involves also the myocardium.

CRP is or is not a reliable marker of ischaemic heart disease?

In recent years a growing body of evidence has emphasized the role of C-reactive protein (CRP) as a marker of future cardiovascular events. CRP is a pentameric molecule widely utilized as a marker of infections and inflammation. The evidence that inflammation plays an important role in the pathogenesis of coronary artery disease and in plaque destabilization has lead to use of CRP as a marker of cardiovascular disease as well. First described as a component of the inflammatory pathway in acute coronary syndromes, CRP has been consistently found to be associated with the risk of future events in no-ST elevation acute coronary syndromes, independently of other risk factors, including troponine. Subsequently CRP has been described as a powerful marker of risk of future events in large populations of apparently healthy subjects. So far there is very little doubt that CRP represents a reliable marker of cardiovascular events, but some issues remain unanswered such as why CRP is a good marker of cardiovascular events and whether or not a better inflammatory marker exists. It must be stressed that CRP, because of its analytical and biological properties and the large amount of available data, is the only inflammatory marker accepted for clinical use.

Endothelium and inflammation

During the past decade, our understanding of the pathophysiology of coronary heart disease (CAD) has undergone a remarkable evolution. To date atherosclerosis is considered an inflammatory disease, whose the endothelial dysfunction represents an early key event. When the arterial endothelium encounters certain bacterial products or risk factors, such as dyslipidemia, vasoconstrictor hormones involved in hypertension, the products of glycoxidation associated with hyperglycemia, or proinflammatory cytokines derived from excess adipose tissue, these cells increase the expression of adhesion molecules that promote the sticking of blood leukocytes to the inner surface of the arterial wall. Once in the arterial intima these cells communicate with endothelium and smooth muscle cells, under the influence of mediators of inflammation and immunity, such as the cytokines and complements components, prostanoids and leukotrienes. Thus, the activated endothelium promotes the development of the atherosclerotic disease process, i.e., vascular inflammation and thrombosis by producing vasoconstrictor substances, by inducing the expression of adhesive receptors for leukocytes and platelets, the production of tissue factor and endothelin, and by increasing the production of the plasminogen activator inhibitor-1. Emerging data support the concept that assessment of endothelial vasomotion may be a useful biomarker for atherosclerotic vascular disease.