Cheyne–Stokes respiration with central sleep apnoea in chronic heart failure: Proposals for a diagnostic and therapeutic strategy

Summary

Central sleep apnoea (CSA) is highly prevalent in the evolutionary course of chronic heart failure. Such a ventilatory pattern during sleep is independently associated with poor prognosis in people with congestive heart failure. Chronic hyperventilation and daytime hypocapnia are the main mechanisms underlying the frequent association between CSA and cardiac failure. Simplified diagnostic strategies allowing easier recognition of CSA among people with severe heart failure are obviously needed but remain to be validated. Treatment of CSA is essentially aimed at improving cardiac function. When CSA persists, after appropriate adjustment of medication and resynchronisation therapy when indicated, specific ventilatory support during sleep should be considered. Continuous positive airway pressure (CPAP), oxygen, adaptive Servo-ventilation (ASV) and non-invasive ventilation have been proposed. Large randomised trials demonstrating survival and time free from heart transplantation are lacking.

Introduction

Congestive heart failure (CHF) in Western societies is a major health issue considering its medical, social and economic consequences.1, 2, 3 Nearly 5 million Americans have CHF today, with an incidence approaching 10 per 1000 among people older than 65 years. In Europe, several studies in people over 45 years have shown that the prevalence of CHF varies from 0.5% in younger people to 16.1% in people over 75 years.4, 5 CHF is the reason for at least 20% of all hospital admissions among people of the same age range. Over the past decades, the rate of hospitalisation for heart failure has increased by 159%.⁶ Medications, mainly beta-blockers, biventricular pacing, coronary bypass surgery, and the use of multidisciplinary teams to treat heart failure, have all been shown to reduce the rate of hospitalisations substantially, as well as reduce mortality or improve functional status. However, symptomatic heart failure continues to confer a worse prognosis than most cancers, with 1-year mortality of about 45%. Thus, factors accompanying the disease, which can contribute to the progression of heart failure and impair its prognosis, are actively being researched. Sleep breathing disorders are common in CHF, and the pathophysiology of the two conditions are closely linked. The need to identify and treat specifically such disorders for improving CHF is still under debate, as Cheyne–Stokes respiration (CSR) might represent a marker of CHF severity.

CSR with central sleep apnoea (CSR-CSA) is a breathing disorder seen in 30–80% of patients with advanced CHF.7, 8, 9 The polysomnographic pattern is characterised by the presence of central apnoeas and hypopnoeas, alternating with periods of tidal volume crescendo–decrescendo. CSR-CSA has been associated, in a severity-dependent manner, with elevations of sympathetic nervous activity in people with CHF, which is an important predictor of CHF progression, arrhythmias and mortality. Indeed, two studies have shown that, in CSR-CSA, independent of other risk factors, the risk of mortality in CHF increases by two- to three-fold.10, 11, 12, 13 However, other studies have not found a higher risk of mortality in people with CHF with CSA.14, 15 Systematic screening for such a nocturnal ventilatory pattern is, therefore, still needed, and treatment efficacy remains to be demonstrated in the overall therapeutic strategy of chronic cardiac failure.

Obstructive sleep apnoea syndrome (OSAS) is characterised by recurrent collapse of the pharyngeal airway during sleep, resulting in repetitive oxygen desaturations. The main symptoms are snoring and daytime sleepiness. It affects 4% of men and 2% of women between the ages of 30 and 60 years. OSAS has important pathological consequences, with an increased incidence of hypertension, arrhythmias, myocardial infarction and stroke. Mortality is increased, and this excess of mortality is secondary to cardiovascular causes. Thus, coronary heart disease associated with OSAS could contribute to the occurrence of chronic left ventricular failure. The therapeutic strategy for OSAS is based on a regular use of nasal CPAP, and this has been clearly established to reduce mortality.¹⁶ In people with CHF with OSAS, CPAP is able to significantly increase cardiac function,17, 18 and the rate of acceptance is usually high.

As the therapeutic strategy is well defined for OSAS associated with cardiac failure, this review will focus on CSR-CSA recognition and management, as there are still unsolved questions. The objective is to provide an overview of the diagnostic, pathophysiological and therapeutic implications of central sleep apnoea in the context of CHF, and also to suggest diagnostic and therapeutic algorithms.