Left atrial remodelling may predict exercise capacity in obstructive sleep apnoea patients

Speckle tracking echocardiography in heart failure development and progression in patients with apneas

Obstructive (OA) and central apneas (CA) are highly prevalent breathing disorders that have a negative impact on cardiac structure and function; while OA promote the development of progressive cardiac alterations that can eventually lead to heart failure (HF), CA are more prevalent once HF ensues. Therefore, the early identification of the deleterious effects of apneas on cardiac function, and the possibility to detect an initial cardiac dysfunction in patients with apneas become relevant. Speckle tracking echocardiography (STE) imaging has become increasingly recognized as a method for the early detection of diastolic and systolic dysfunction, by the evaluation of left atrial and left and right ventricular global longitudinal strain, respectively. A growing body of evidence is available on the alterations of STE in OA, while very little is known with regard to CA. In this review, we discuss the current knowledge and gap of evidence concerning apnea-related STE alterations in the development and progression of HF.

Obstructive sleep apnea increases the risk of cardiovascular damage: a systematic review and meta-analysis of imaging studies

BACKGROUND

We aimed to perform a systematic review and meta-analysis of the association between obstructive sleep apnea (OSA) and cardiac as well as coronary impairment evaluated using imaging modalities. Finding of this study will provide more robust evidence regarding OSA-induced cardiovascular damage.

METHODS

We systematically searched through PubMed, EMBASE, and Cochrane library databases for relevant literatures on the association between OSA and cardiovascular damage evaluated using imaging modalities, and manually searched the references of selected articles for additional relevant articles. For each clinical parameter relevant to the meta-analysis, we first evaluated the methodological heterogeneity of the relevant studies and thereafter pooled the data together using fixed effect or random effect model. The difference in the relevant indices of cardiovascular damage between OSA patients and controls was evaluated using the standardized mean difference.

RESULTS

Of the 82 articles included in the final systematic analysis, 20 studies explored the association between OSA and coronary atherosclerosis. OSA patients had higher rate of coronary atherosclerosis assessed by coronary artery calcification score and plaque volume. Moreover, the severity of OSA and coronary atherosclerosis displayed a positive correlation. The rest of the studies (n = 62) evaluated cardiac alterations in OSA patients. According to the inclusion and exclusion criteria, 46 studies yielding 3082 OSA patients and 1774 controls were pooled for the meta-analysis. For left cardiac structure and function, OSA patients exhibited significantly wider left atrial diameter; higher left atrium volume index; wider left ventricular end-systolic diameter, left ventricular end-diastolic diameter, and left ventricular mass; higher left ventricular mass index; wider interventricular septum diameter and posterior wall diameter; and higher left ventricular myocardial performance index (all p < 0.05). In addition, compared with controls, left ventricular ejection fraction was significantly decreased in OSA patients (p = 0.001). For right cardiac structure and function, OSA patients displayed a significant increase in right ventricular diameter and right ventricular myocardial performance index (both p < 0.001). Finally, compared with controls, OSA patients displayed significant decrease in tricuspid annular plane systolic excursion and RV fractional area change (p = 0.001).

CONCLUSION

Overall, this systematic review and meta-analysis provides imaging evidence in support that OSA patients are at a higher risk of developing coronary atherosclerosis and display cardiac remodeling and dysfunction.

Ventilatory response to exercise is preserved in patients with obesity hypoventilation syndrome

STUDY OBJECTIVES

Blunted ventilatory responses to hypoxia and hypercapnia during resting conditions are common findings in patients with obesity hypoventilation syndrome (OHS). Exercise increases the work and oxygen cost of breathing and produces excessive carbon dioxide (CO₂). The aim of this investigation was to study ventilatory responses to incremental exercise in patients with OHS.

METHODS

Sixty-eight obese adults with OHS (n = 15), eucapnic obstructive sleep apnea (n = 26), or simple obesity (n = 27) participated in an incremental exercise test on a cycle ergometer and an in-laboratory sleep study.

RESULTS

The peak oxygen uptake (peak VO₂) and peak pulse oxygen was decreased in patients with OHS compared with patients with either obstructive sleep apnea or simple obesity. The ventilatory response to exertional metabolic demand (nadir VE/VCO₂, ∆VE/∆VCO₂ slope, and VE/VCO₂ at peak exercise) did not significantly differ among the 3 groups. Minute ventilation, tidal volume, respiratory frequency, tidal volume/respiratory frequency, and inspiratory time/total time ratio at a given work rate were comparable among the 3 groups. Among the whole cohort, apnea-hypopnea index was not independently associated with peak VO₂, and no association was found between the ∆VE/∆VCO₂ slope and resting arterial partial pressure of CO₂.

CONCLUSIONS

The ventilatory response to incremental exercise is preserved in patients with OHS compared with patients with obstructive sleep apnea and simple obesity who were matched for age and body mass index. This result highlights the complexity of the respiratory control system during exercise for patients with OHS, which may be uncoupled with the ventilatory response during sleep and resting conditions.

Undiagnosed sleep apnoea in cardiac rehabilitation: Age-dependent effect on diastolic function in coronary artery disease patients with preserved ejection fraction

BACKGROUND

Focusing on detection of sleep apnoea early in the cardiac rehabilitation process may improve the recovery process and reduce recurrence of cardiovascular events. Patients who continue to be undiagnosed may experience a significantly worse outcome during their cardiac rehabilitation and recovery. Diastolic dysfunction has both diagnostic and prognostic importance in the management of coronary artery disease. We hypothesise that undiagnosed/untreated sleep apnoea in middle-aged coronary artery disease patients with preserved left ventricular ejection fraction changes the pattern of diastolic filling close to that in elderly patients without sleep apnoea.

METHODS AND RESULTS

This cross-sectional study included the 450 coronary artery disease patients with undiagnosed sleep apnoea who had left ventricular ejection fraction ⩾50% and were referred consecutively to the Clinic of Cardiovascular Rehabilitation within two weeks after treatment for acute coronary syndrome. Polysomnographic and echocardiographic measurements were analysed. Mild to severe sleep apnoea was defined as the apnoea-hypopnea index ⩾5. Age was dichotomised into under the age of 60 years and age 60 years or over. Up to 35% of coronary artery disease patients were likely to have undiagnosed sleep apnoea. There was a statistically significant interaction between the effect of sleep apnoea and age group on diastolic function defined as the ratio peak flow velocity in early diastole/peak flow velocity in atrial contraction ratio (p=0.036). This ratio was significantly (p=0.029) lower in the mild-severe sleep apnoea group (0.97, 95% confidence interval 0.88-1.06) than in the non-sleep apnoea group (1.09, 95% confidence interval 1.03-1.15) among middle aged (<60 years) coronary artery disease patients. Therefore, filling patterns in the middle aged (<60 years) patients with sleep apnoea resemble those observed in the elderly (⩾60 years) patients without sleep apnoea. The effect of sleep apnoea on left ventricular filling pattern in elderly was not observed.

CONCLUSIONS

Age modifies the effect of sleep apnoea on cardiovascular outcomes. The findings that undiagnosed sleep apnoea impairs diastolic function in a middle-aged coronary artery disease patient underscore the importance of early diagnosis and treatment of sleep apnoea. It is recommended to train and educate cardiac rehabilitation staff on the importance of sleep disorders in this population.

Subclinical impairment of dynamic left ventricular systolic and diastolic function in patients with obstructive sleep apnea and preserved left ventricular ejection fraction

Background

Hypoxia affects myocardial oxygen supply resulting in subclinical cardiac dysfunction in obstructive sleep apnea (OSA) patients, with cardiovascular complications being associated with increased oxidative burst (OB). The aims of our study were to assess left ventricular (LV) dynamic myocardial deformation and diastolic reserve at rest and upon exercise, along with OB determination in this patients subset.

Methods

Conventional echocardiography, Doppler myocardial imaging and LV 2D speckle tracking echocardiography were performed in 55 OSA patients with preserved LV ejection fraction (EF) and 35 age and sex-comparable healthy controls. Peripheral OB levels were evaluated by flow cytometry.

Results

Despite comparable LVEF, LV global longitudinal strain (GLS) was significantly reduced in OSA at rest (− 13.4 ± 3.8 vs − 18.4 ± 3.3 in controls, P <  0.001) and at peak exercise (− 15.8 ± 2.6 vs − 23.4 ± 4.3, P <  0.001). Systolic pulmonary artery pressure (sPAP) and E/E′ ratios increase during effort were higher in OSA than in controls (ΔsPAP 44.3% ± 6.4 vs 32.3% ± 5.5, P <  0.0001, and ΔE/E’ 87.5% ± 3.5 vs 25.4% ± 3.3, P <  0.0001, respectively). The best correlate of E/E′ at peak stress was peak exertion capacity (r = − 0.50, P <  0.001). OB was also increased in OSA patients (P = 0.001) but, unlike OSA severity, was not associated with LV diastolic dysfunction.

Conclusions

Evaluation of diastolic function and myocardial deformation during exercise is feasible through stress echocardiography. OSA patients with preserved LVEF show subclinical LV systolic dysfunction, impaired LV systolic and diastolic reserve, reduced exercise tolerance, and increased peripheral levels of OB. Therapy aimed at increasing LV diastolic function reserve might improve the quality of life and exercise tolerability in OSA patients.

Obstructive sleep apnea and cardiac mechanics: how strain could help us?

Obstructive sleep apnea (OSA) syndrome is the most common sleep-breathing disorder, which is associated with increase cardiovascular morbidity and mortality. OSA increases risk of resistant arterial hypertension, coronary artery disease, heart failure, pulmonary hypertension, and stroke. Studies showed the significant relationship between OSA and cardiac remodeling. The majority of investigations were focused on the left ventricle and its hypertrophy and function. Fewer studies investigated right ventricular structure and function revealing deteriorated diastolic and systolic function. Data regarding left and right ventricular mechanics in OSA patients are scarce and controversial. The results of the studies that were focused on the influence of continuous positive airway pressure and weight reduction on cardiac remodeling revealed favorable effect on left and right ventricular structure and function. Recently published analyses confirmed positive effect of treatment on cardiac mechanics. Deterioration of left and right ventricular mechanics occurs before functional and structural cardiac impairments in the cascade of cardiac remodeling and therefore the assessment of left and right ventricular strain may represent a cornerstone in detection of subtle cardiac changes that develop significantly before other, often irreversible, alterations. Considering the fact that left and right ventricular strains have important predictive value in wide range of cardiovascular diseases, one should consider the evaluation of left and right ventricular strains in the routine echocardiographic assessment at all stages of disease-from diagnosis, during follow-up and evaluation of therapeutic effects. The main aim of this review is to provide the current overview of cardiac mechanics in OSA patients before and after (during) therapy, as well as mechanisms that could be responsible for cardiac changes.