Is the morning peak of acute myocardial infarction's onset due to sleep-related breathing disorders? A prospective study

Fluctuaciones nocturnas de presión arterial en el síndrome de apnea-hipopnea obstructiva del sueño

Objective

Patients with sleep apnea/hypopnea syndrome and episodes of increased systolic pressure during sleep, with and without arterial hypertension, and HT as a marker of increased cardiovascular risk, were studied in a prospective study. The objective of our study was to demonstrate that patients with increased systolic pressure during sleep who also had arterial hypertension had a higher cardiovascular risk than non-hypertensive patients.

Methods

We analyzed various biometric (muscle mass index, baseline blood pressure) and polysomnographic parameters, including AHI (apnea-hypopnea index/hour), O2 desaturation index/hour, arousal index, baseline and minimum O2 saturation and the proportion of different sleep phases, together with comorbidities and associated treatments in patients with sleep apnea/hypopnea syndrome (64 with arterial hypertension and 38 non-hypertensive patients) with episodes of increased systolic blood pressure during sleep during polysomnographic studies conducted between 2013 and 2017 and in 2020.

Results

There were no statistically significant differences in the different parameters between study groups. Patients in both groups developed comorbidities in the follow-up period, more frequently in the hypertensive group, and required new treatments, especially the group of patients with HT.

Conclusion

Episodes of increased systolic pressure during sleep suggest an increased cardiovascular risk in patients with sleep apnea syndrome and arterial hypertension in terms of associated comorbidities. However, in non-hypertensive patients, episodes of increased systolic pressure may also be associated with a higher risk of vascular comorbidities (higher than the risk associated with isolated obstructive sleep apneas).

Nocturnal blood pressure fluctuations measured by using pulse transit time in patients with severe obstructive sleep apnea syndrome

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) is related to arterial hypertension. In the present study, we test the hypothesis that patients with severe OSAS have excessive apnea induced blood pressure (BP).

METHODS

We investigated 97 patients with an apnea/hypopnea index (AHI) greater than 30. Systolic BP (SBP) was continuously determined by using the pulse transit time (PTT). Apnea/hypopnea induced nocturnal BP fluctuations (NBPFs) were detected and showed phenomena of continuous increases of the SBP baseline. Such periods of SBP baseline elevations ≥ 10 mmHg were called superposition. Respiratory and cardiac parameters were obtained from the polysomnographic investigation.

RESULTS

Eighty-four periods of superposition were detected in 48 patients. They occurred mainly during REM sleep (76%). Apnea duration was increased and the time in respiration was reduced in periods of superposition compared to non-superposition periods. In superposition periods mean oxygen saturation (SpO₂) and the minimal SpO₂ were lower, desaturations were more pronounced, and the mean heart rate (HR) was increased. The maximum SBP during superposition was significantly increased (204 ± 32 vs.171 ± 28 mmHg). The clinic BP was higher in patients with superposition (SBP 149.2 ± 17.5 vs. 140 ± 19.1, DBP 91.5 ± 11.5 vs. 86.3 ± 11.8).

CONCLUSIONS

The study reveals that patients with severe OSAS can have periods of BP superposition during night with extremely high SBP and very low oxygen saturation, which may add to a high risk for cardiovascular events during the night.

Increased C-C chemokine receptor 2 gene expression in monocytes of severe obstructive sleep apnea patients and under intermittent hypoxia

Background

Obstructive sleep apnea (OSA) is known to be a risk factor of coronary artery disease. The chemotaxis and adhesion of monocytes to the endothelium in the early atherosclerosis is important. This study aimed to investigate the effect of intermittent hypoxia, the hallmark of OSA, on the chemotaxis and adhesion of monocytes.

Methods

Peripheral blood was sampled from 54 adults enrolled for suspected OSA. RNA was prepared from the isolated monocytes for the analysis of C-C chemokine receptor 2 (CCR2). The effect of intermittent hypoxia on the regulation and function of CCR2 was investigated on THP-1 monocytic cells and monocytes. The mRNA and protein expression levels were investigated by RT/real-time PCR and western blot analysis, respectively. Transwell filter migration assay and cell adhesion assay were performed to study the chemotaxis and adhesion of monocytes.

Results

Monocytic CCR2 gene expression was found to be increased in severe OSA patients and higher levels were detected after sleep. Intermittent hypoxia increased the CCR2 expression in THP-1 monocytic cells even in the presence of TNF-α and CRP. Intermittent hypoxia also promoted the MCP-1-mediated chemotaxis and adhesion of monocytes to endothelial cells. Furthermore, inhibitor for p42/44 MAPK or p38 MAPK suppressed the activation of monocytic CCR2 expression by intermittent hypoxia.

Conclusions

This is the first study to demonstrate the increase of CCR2 gene expression in monocytes of severe OSA patients. Monocytic CCR2 gene expression can be induced under intermittent hypoxia which contributes to the chemotaxis and adhesion of monocytes.

Sleep apnea prevalence in acute myocardial infarction--the Sleep Apnea in Post-acute Myocardial Infarction Patients (SAPAMI) Study

BACKGROUND

While sleep apnea (SA) might be a modifiable cardiovascular risk factor, recent data suggest that SA is severely underdiagnosed in patients after acute myocardial infarction (MI). There is limited evidence about day-night variation of onset of MI on dependence of having SA. We therefore investigated the prevalence of SA and examined the day-night variation of onset of MI in acute MI patients.

METHODS

We prospectively studied 782 consecutive patients admitted to the hospital with the diagnosis of acute MI. All subjects underwent sleep evaluations using a portable device after at least 48 h post-admission. Using the apnea-hypopnea index (AHI), groups were defined as patients without SA (<5 events/h), mild SA (5-15 events/h), moderate SA (15-30 events/h), and severe SA (≥ 30 events/h).

RESULTS

Almost all patients (98%) underwent urgent coronary angiography and 91% of patients underwent primary PCI. Using a threshold of AHI ≥ 5 events/h, SA was present in 65.7% of patients after acute MI. Mild SA was present in 32.6%, moderate in 20.4% and severe in 12.7%. The day-night variation in the onset of MI in all groups of SA patients was similar to that observed in non-SA patients. From 6 AM to 12 PM, the frequency of MI was higher in both SA and non-SA patients, as compared to the interval from 12 AM to 6 AM (all p<0.05).

CONCLUSION

There is a high prevalence of SA in patients presenting with acute MI. Peak time of MI onset in SA patients was between 6 AM and noon, similar to that in the general population. Whether diagnosis and treatment of SA after MI will significantly improve outcomes in these patients remains to be determined.

Obstructive sleep apnoea increases the incidence of morning peak of onset in acute myocardial infarction

AIMS

There exists a discrepancy regarding the relationship between obstructive sleep apnoea (OSA) and circadian variation during the onset of acute myocardial infarction (MI). We hypothesized that OSA patients show a characteristic circadian variation and that the severity of OSA significantly affects this variation.

METHODS AND RESULTS

The present study included 288 patients with first acute MI who underwent percutaneous coronary intervention within 12 h of symptom onset. The diagnosis of OSA required an apnoea-hypopnoea index (AHI) of ≥5 events/h. A total of 216 patients fulfilled the OSA criteria. The incidence of MI onset between 06:00 and 11:59 hours was significantly higher in OSA patients than in control patients (38 vs. 25%, p=0.039). Circadian variation in the morning peak of MI onset was attenuated in mild OSA (as defined by AHI, 5.0-14.9 events/h; 33 vs. 25%, p=0.240). Moderate-to-severe OSA (as defined by AHI ≥15.0 events/h) clearly increased the incidence of MI onset between 06:00 and 11:59 hours (43 vs. 25%, p=0.014). Multiple logistic regression adjusting for AHI (≥15.0 events/h), age, body mass index, hypertension, and current smoking showed that moderate-to-severe OSA significantly contributed to MI onset between 06:00 and 11:59 hours (odds ratio 2.00, p=0.010).

CONCLUSIONS

OSA showed a morning peak with regard to MI onset, and moderate-to-severe OSA significantly enhanced this circadian variation.

Cardiovascular complications of obstructive sleep apnea

Obstructive sleep apnea (OSA) is a common disorder with an increasing public health burden. It is characterized by repeated upper airway narrowing and closure, leading to apneas, hypopneas and increased respiratory effort-related arousals. Continuous positive airway pressure is an effective modality of treatment for OSA. Apart from being responsible for daytime sleepiness and cognitive impairment, OSA has been implicated in various systemic diseases, particularly of the cardiovascular system. This article reviews some of the extensive literature implicating OSA in the development of cardiovascular diseases and describes the intermediary pathophysiologic mechanisms involved. Repetitive nocturnal oxygen desaturation and reoxygenation and increased intrathoracic pressure changes related to OSA result in the intermediary pathophysiologic mechanisms that affect the neural, humoral, thrombotic, inflammatory and metabolic pathways responsible for the development of cardiovascular disorders. This review also examines evidence that suggests that OSA may be a specific cause of certain cardiovascular disorders.

The coagulation and protein C pathways in patients with sleep apnea

Patients with obstructive sleep apnea (OSA) have a high frequency of cardiovascular diseases and hypercoagulability is believed to be involved in the mechanism of those vascular events. We evaluated whether there is a dysfunction in the protein C anticoagulant pathway in patients with obstructive sleep apnea. Two hundred ninety-three patients were enrolled. To confirm the diagnosis of OSA, all-night polysomnography, including determination of SpO(2), was carried out. The apnea-hypopnea index (AHI) was used for judging the presence of sleep-breathing disorder. The plasma levels of the thrombin-antithrombin complex were higher in patients with AHI > 5 than in those without OSA, defined as AHI < 5. However, there was no statistically significant difference in the plasma level of either activated protein C/alpha-antitrypsin complex or soluble thrombomodulin between patients with AHI > 5 and those with AHI < 5. The results of this study showed for the first time that markers of the protein C anticoagulant pathway are not affected in patients with OSA and that the protein C pathway is probably not involved in the mechanism of hypercoagulability in subjects with sleep-disordered breathing.

The link between obstructive sleep apnea and heart failure: underappreciated opportunity for treatment

Obstructive sleep apnea (OSA) is a newly recognized risk factor for the development of systemic hypertension, ischemic heart disease, and congestive heart failure. Mechanisms responsible for these links include OSA-related hypoxemia and arousal from sleep-induced increased sympathetic activity, large negative intrathoracic pressure-induced increased left ventricular transmural pressure gradient and impaired vagal activity, plus formation of oxygen radicals. Secondary phenomena include increased platelet aggregability, insulin resistance, and endothelial dysfunction with reduced endogenous nitric oxide production. Safe, nonpharmacologic, nonsurgical therapy, namely continuous positive airway pressure, can attenuate OSA and improve cardiac function and quality of life. Searching for signs or symptoms of OSA from the patient (or bed partner), namely loud habitual snoring, apneas, nocturnal choking, orthopnea, paroxysmal nocturnal dyspnea, excessive daytime sleepiness, or cardiovascular disease which is difficult to control, may reward the curious physician with another treatment avenue.

Erythrocyte deformability, plasma viscosity and oxidative status in patients with severe obstructive sleep apnea syndrome

BACKGROUND AND PURPOSE

In patients with severe obstructive sleep apnea syndrome (OSAS), diurnal changes of plasma viscosity and erythrocyte deformability were measured to elucidate the possible mechanism of cardiovascular diseases in OSAS patients.

PATIENTS AND METHODS

Plasma viscosity and erythrocyte deformability was determined in 11 OSAS patients and 11 healthy subjects matched by sex and age. Plasma viscosity was measured by a cone-plate viscometer, and erythrocyte deformability was determined by filtration technique. Whole blood counts were performed and oxidative status of the patients' plasma and erythrocytes were evaluated.

RESULTS

OSAS patients had higher plasma viscosity than controls, both in the morning (1.74+/-0.3 vs. 1.36+/-0.2 mPas, P<0.002) and evening (1.55+/-0.2 vs. 1.27+/-0.1 mPas, P<0.002), and morning plasma viscosity was significantly higher than the evening level (P<0.05). Morning plasma viscosity of patients was inversely correlated with their mean nocturnal SaO(2). Morning plasma malonyldialdehyde level was significantly higher in the patients than in the controls (69.7+/-30.5 vs. 45.5+/-11.0 nmol/l, P<0.005). Erythrocyte deformability of the patients was slightly lower.

CONCLUSIONS

We have observed that plasma viscosity is high both in the morning and in the evening in severe OSAS patients. This elevation may predispose OSAS patients to myocardial infarction and stroke by increasing blood viscosity. Low nocturnal mean SaO(2) may be responsible for the high plasma viscosity in these patients.

The link between obstructive sleep apnea and heart failure: Underappreciated opportunity for treatment

Obstructive sleep apnea (OSA) is a newly recognized risk factor for the development of systemic hypertension, ischemic heart disease and congestive heart failure. Mechanisms responsible for these links include OSA-related hypoxemia and arousal from sleep-induced increased sympathetic activity, large negative intrathoracic pressure-induced increased left ventricular transmural pressure gradient, and impaired vagal activity plus oxygen radial formation. Secondary phenomena include increased platelet aggregability, insulin resistance, and endothelial dysfunction with reduced endogenous nitric oxide production. Safe nonpharmacologic, nonsurgical therapy, namely continuous positive airway pressure, can attenuate OSA, and improve cardiac function and quality of life. Searching for signs or symptoms of OSA from the patient (or bed partner), namely loud habitual snoring, apneas, nocturnal choking, orthopnea, paroxysmal nocturnal dyspnea, excessive daytime sleepiness, or cardiovascular disease, which is difficult to control, may reward the curious physician with another treatment avenue.

Behavioral and emotional triggers of acute coronary syndromes: a systematic review and critique

OBJECTIVE

The objective of this study was to review the evidence that behavioral and emotional factors are triggers of acute coronary syndromes.

METHOD

Systematic review of the published literature from 1970 to 2004 of trigger events, defined as stimuli or activities occurring within 24 hours of the onset of acute coronary syndromes.

RESULTS

There is consistent evidence that physical exertion (particularly by people who are not normally active), emotional stress, anger, and extreme excitement can trigger acute myocardial infarction and sudden cardiac death in susceptible individuals. Many triggers operate within 1 to 2 hours of symptom onset. There are methodologic limitations to the current literature, including sampling, retrospective reporting, and presentation biases, the role of memory decay and salience, and reverse causation because of silent prodromal events.

CONCLUSIONS

Behavioral and emotional factors are probable triggers of acute coronary syndromes in vulnerable individuals, and the pathophysiological processes elicited by these stimuli are being increasingly understood. The benefits to patients of knowledge to these processes have yet to accrue.