Are there any unique epidemiological and vascular risk factors for ischaemic strokes that occur in the morning hours?

Thrombolytic therapy for wake-up stroke: A systematic review and meta-analysis

BACKGROUND AND PURPOSE

According to evidence-based clinical practice guidelines, patients presenting with disabling stroke symptoms should be treated with intravenous tissue plasminogen activator (IV tPA) within 4.5 h of time last known well. However, 25% of strokes are detected upon awakening (i.e., wake-up stroke [WUS]), which renders patients ineligible for IV tPA administered via time-based treatment algorithms, because it is impossible to establish a reliable time of symptom onset. We performed a systematic review and meta-analysis of the efficacy and safety of IV tPA compared with normal saline, placebo, or no treatment in patients with WUS using imaging-based treatment algorithms.

METHODS

We searched MEDLINE, Web of Science, and Scopus between January 1, 2006 and April 30, 2020. We included controlled trials (randomized or nonrandomized), observational cohort studies (prospective or retrospective), and single-arm studies in which adults with WUS were administered IV tPA after magnetic resonance imaging (MRI)- or computed tomography (CT)-based imaging. Our primary outcome was recovery at 90 days (defined as a modified Rankin Scale [mRS] score of 0-2), and our secondary outcomes were symptomatic intracranial hemorrhage (sICH) within 36 h, mortality, and other adverse effects.

RESULTS

We included 16 studies that enrolled a total of 14,017 patients. Most studies were conducted in Europe (37.5%) or North America (37.5%), and 1757 patients (12.5%) received IV tPA. All studies used MRI-based (five studies) or CT-based (10 studies) imaging selection, and one study used a combination of modalities. Sixty-one percent of patients receiving IV tPA achieved an mRS score of 0 to 2 at 90 days (95% confidence interval [CI]: 51%-70%, 12 studies), with a relative risk (RR) of 1.21 compared with patients not receiving IV tPA (95% CI: 1.01-1.46, four studies). Three percent of patients receiving IV tPA experienced sICH within 36 h (95% CI: 2.5%-4.1%; 16 studies), which is an RR of 4.00 compared with patients not receiving IV tPA (95% CI: 2.85-5.61, seven studies).

CONCLUSIONS

This systematic review and meta-analysis suggests that IV tPA is associated with a better functional outcome at 90 days despite the increased but acceptable risk of sICH. Based on these results, IV tPA should be offered as a treatment for WUS patients with favorable neuroimaging findings.

Blood pressure control and primary prevention of stroke: summary of the recent clinical trial data and meta-analyses

Stroke is the second most common cause of death worldwide and of adult disability, but in the near future the global burden of cerebrovascular diseases will rise due to ageing and adverse lifestyle changes in populations worldwide. The risk of stroke increases at blood pressure levels above 115/75 mm Hg and high blood pressure (BP) is the most important modifiable risk factor for stroke, associated with 54 % episodes of stroke worldwide. There is strong evidence from clinical trials that antihypertensive therapy reduces substantially the risk of any type of stroke, as well as stroke-related death and disability. The risk attributed to BP is associated not only with absolute values but also with certain parameters describing BP diurnal pattern as well as short-term and long-term variability. Many studies reported that certain features of BP like nocturnal hypertension, morning surge or increased variability predict an increased stroke risk. However, there is no accepted effective modality for correction of these disturbances (chronotherapy, certain classes of antihypertensive drugs). In the elderly, who are mostly affected by stroke, the primary prevention guidelines recommend treatment with diuretics and calcium channel blockers to lower blood pressure to the standard level.

Circadian rhythm of stroke onset during the month of Ramadan

BACKGROUND AND PURPOSE

The onset of acute stroke exhibits a circadian pattern occurring more frequently in late morning hours. The objective of this study was to investigate the diurnal pattern of stroke during the month of Ramadan.

PATIENTS AND METHODS

We studied consecutive stroke patients 1 month before Ramadan (BR) and during Ramadan (DR) over two successive years 2007 and 2008. The age, gender, risk factor profiles were analyzed. The National Institute of Health and Stroke Scale Score (NIHSS) was used for clinical assessment at admission. The exact time of stroke onset in both groups was obtained.

RESULTS

A total of 507 patients were studied: 245 patients in the DR group and 262 patients in the BR group. The age distribution of patients was not significantly different between the two groups. There was no statistically significant difference in the sex ratio, risk factors, and NIHSS score between the two groups (P > 0.05). The higher frequency of stroke onset time in the BR group was in the time between 6:00 a.m. and noon; whereas the frequency was higher between noon and 6:00 p.m. in the DR group.

CONCLUSION

A significant shift of the circadian pattern of stroke onset time from the period between 6:00 a.m. and noon to that between noon and 6:00 pm has been found during the month of Ramadan.

Circadian variation in the circulatory responses to exercise: relevance to the morning peaks in strokes and cardiac events

Sudden cardiac and cerebral events are most common in the morning. A fundamental question is whether these events are triggered by the increase in physical activity after waking, and/or a result of circadian variation in the responses of circulatory function to exercise. Although signaling pathways from the master circadian clock in the suprachiasmatic nuclei to sites of circulatory control are not yet understood, it is known that cerebral blood flow, autoregulation and cerebrovascular reactivity to changes in CO(2) are impaired in the morning and, therefore, could explain the increased risk of cerebrovascular events. Blood pressure (BP) and the rate pressure product (RPP) show marked 'morning surges' when people are studied in free-living conditions, making the rupture of a fragile atherosclerotic plaque and sudden cardiac event more likely. Since cerebral autoregulation is reduced in the morning, this surge in BP may also exacerbate the risk of hemorrhagic and ischemic strokes in the presence of other acute and chronic risk factors. Increased sympathetic activity, decreased endothelial function, and increased platelet aggregability could also be important in explaining the morning peak in cardiac and cerebral events but how these factors respond to exercise at different times of day is unclear. Evidence is emerging that the exercise-related responses of BP and RPP are increased in the morning when prior sleep is controlled. We recommend that such 'semi-constant routine' protocols are employed to examine the relative influence of the body clock and exogenous factors on the 24-h variation in other circulatory factors.

Circadian Variation in Stroke Onset: Identical Temporal Pattern in Ischemic and Hemorrhagic Events

Stroke is the culmination of a heterogeneous group of cerebrovascular diseases that is manifested as ischemia or hemorrhage of one or more blood vessels of the brain. The occurrence of many acute cardiovascular events--such as myocardial infarction, sudden cardiac death, pulmonary embolism, critical limb ischemia, and aortic aneurysm rupture--exhibits prominent 24 h patterning, with a major morning peak and secondary early evening peak. The incidence of stroke exhibits the same 24 h pattern. Although ischemic and hemorrhagic strokes are different entities and are characterized by different pathophysiological mechanisms, they share an identical double-peak 24 h pattern. A constellation of endogenous circadian rhythms and exogenous cyclic factors are involved. The staging of the circadian rhythms in vascular tone, coagulative balance, and blood pressure plus temporal patterns in posture, physical activity, emotional stress, and medication effects play central and/or triggering roles. Features of the circadian rhythm of blood pressure, in terms of their chronic and acute effects on cerebral vessels, and of coagulation are especially important. Clinical medicine has been most concerned with the prevention of stroke in the morning, when population-based studies show it is of greatest risk during the 24 h; however, improved protection of at-risk patients against stroke in the early evening, the second most vulnerable time of cerebrovascular accidents, has received relatively little attention thus far.

Why a polysomnogram should become part of the diagnostic evaluation of stroke and transient ischemic attack

Neurologists need to recognize, diagnose, and treat obstructive sleep apnea (OSA) in patients with stroke or transient ischemic attack (TIA). Increasing medical evidence suggests that OSA is an independent risk factor for stroke and TIA. Stroke (or TIA) is more likely a cause, rather than a consequence, of OSA because PSG studies have shown: 1) apneas in stroke are typically obstructive, not central or Cheyne-Stokes in type; 2) apneas are just as frequent and severe in patients with either TIA or stroke; 3) OSA severity is not influenced by the acuteness or location of the stroke; 4) untreated OSA patients have more strokes, stroke morbidity, and mortality than those who are treated. OSA alone can induce hypertension, especially in younger men. A causal relationship has recently been demonstrated between OSA and hypertension. A distinctive feature of OSA-induced hypertension is loss of the normal nighttime fall in blood pressure ("nondippers"). Data from the Sleep Heart Health Study showed a dose-response association between OSA severity and the presence of hypertension 4 years later. Hypertension or ischemic heart disease usually develops in untreated patients with OSA over time without particular worsening of OSA. Studies have shown sleep itself is not a risk factor for stroke because most stroke and TIAs begin between 6 am and noon, while the individual is awake. However, OSA promptly be considered in stroke beginning during sleep because 88% of strokes that develop during sleep occur in "nondippers." Premature death in OSA patients is most often cardiovascular, but occurs while the patients are awake. The risk of myocardial infarction is increased 20-fold in untreated OSA. Treating OSA patients with continuous positive airway pressure can prevent or improve hypertension, reduce abnormal elevations of inflammatory cytokines and adhesion molecules, reduce excessive sympathetic tone, avoid increased vascular oxidative stress, reverse coagulation abnormalities, and reduce leptin levels. If all this can be achieved by a polysomnogram, then this test should become part of a neurologist's armamentarium for stroke and TIA.

Circadian variation in stroke - a prospective hospital-based study

A particular pattern of circadian variation of cardiovascular and cerebrovascular diseases has been reported in the literature. The circadian periodicity of ischaemic stroke with peak onset in the morning hours may not be a random event and could depend on some underlying precipitating and associated cardiovascular risk factors. In a prospective observational study, we observed that ischaemic stroke onset was significantly higher in late morning hours between 6.00 and 12.00 hours. Ischaemic heart disease and hypertension were significantly associated with the occurrence of late morning ischaemic strokes. Further studies in the future are needed to understand the significance of this association and whether these risk factors are implicated in the pathogenesis of stroke.

Dyslipidemia, elevated LDL cholesterol and reduced nocturnal blood pressure dipping denote lacunar strokes occurring during nighttime

Previous studies have shown a peak occurrence of ischemic stroke in the morning but no consistent finding has been attributed to this. Focused on lacunar strokes we performed a prospective study with a detailed diagnostic protocol including parameters of recent infection, indicators of sleep apnea and cerebral vasoreactivity (CVR), aimed at defining differences in risk profiles between diurnal and nocturnal strokes. Consecutively we included 33 nocturnal and 54 diurnal strokes. Baseline characteristics, known risk factors, stroke severity and topology were not different between groups. The mean low-density lipoprotein (LDL) cholesterol level was significantly higher amongst patients with nocturnal strokes (133.3 +/- 35.2 mg/dl vs. 115.5 +/- 39.8 mg/dl; P = 0.04), as well as the proportion of patients with any dyslipidemia (94% vs. 77.8%; P = 0.047). Twenty-four-hour blood pressure recordings showed a reduced nocturnal decrease of blood pressure in subjects with strokes that occurred between 10 pm and 6 am in comparison with those whose strokes occurred between 6 am and 2 pm (5.0 +/- 7.3% vs. 11.0 +/- 6.7%; P = 0.049). No significant differences were found for parameters of recent infection (including seroreactivity against Chlamydia pneumoniae and cytomegalovirus), CVR, indicators of sleep apnea and the degree of white matter disease assessed by magnetic resonance tomography. Dyslipidemia, especially elevated LDL cholesterol is more prevalent in nocturnal lacunar strokes especially when combined with a reduced nocturnal dipping of blood pressure. This risk factor profile can be regarded as an additional target for stroke prevention.

Diurnal and seasonal variation of stroke incidence in patients with cardioembolic stroke due to atrial fibrillation

A seasonal variation with an incidence peak during the colder period of the year, as well as a circadian distribution with a single peak of stroke onset in the morning hours are described in various countries. Cardioembolic stroke seems to be the most frequent stroke subtype among Greek patients. Atrial fibrillation is identified as the most frequent cause of stroke. Analysis of the temporal pattern of symptom onset in a series of over 300 Greek patients with first-ever cardioembolic acute stroke due to atrial fibrillation revealed a circannual distribution with a peak during winter and a decline of stroke occurrence during summer. Analysis of the diurnal variation of symptom onset in this stroke subgroup showed a distribution with 2 incidence peaks between 08:00-10:00 and 16:00-18:00. A relation between the second, however lower, frequency peak and the traditional Greek habit of afternoon sleep (siesta) could be assumed. Possible clustering of cardiologic events in patients with atrial fibrillation, especially during the time interval after awakening from night and afternoon sleep, could be a plausible explanation, which certainly deserves to be further investigated.

Two-peak temporal distribution of stroke onset in Greek patients. a hospital-based study

A circadian distribution with a single peak of stroke onset in the morning hours has been described in various countries. Analysis of the temporal pattern of symptom onset in a series of 1253 Greek first-ever stroke patients revealed a circadian distribution with two incidence peaks between 08.00 and 10.00 h, and between 16.00 and 18.00 h. Considering the different etiopathogenic types of stroke, the same two-peak time pattern was evaluated in all stroke subgroups with the only exception of lacunar stroke, which seems to predominantly occur during night and sleep. A secondary stroke onset peak in the late afternoon has not been previously described in such detail. A relation between the second, however lower, frequency peak and the traditional Greek habit of afternoon sleep (siesta) could be assumed and deserves further investigation.

Effects of angiotensins on day-night fluctuations and stress-induced changes in blood pressure

In this study we evaluated by telemetry the effects of ANG II and ANG-(1-7) infusion on the circadian rhythms of blood pressure (BP) and heart rate (HR) and on the cardiovascular adjustment resulting from restraint stress in rats. ANG II or ANG-(1-7) or vehicle were infused subcutaneously for 7 days. Restraint stress was carried out before, during, and after infusion at 7-day intervals. Parallel with an increase in MAP, ANG II infusion produced an inversion of MAP circadian rhythm with a significant MAP acrophase inversion. It also produced bradycardia during the first 3 days of infusion. Thereafter, HR progressively increased, reaching values similar to or above those of the control period at the end of the infusion period. HR circadian variation was not changed by ANG II infusion. Strikingly, ANG II significantly attenuated the increase in MAP induced by restraint stress without altering the HR response. ANG-(1-7) infusion produced a slight but significant decrease in MAP restricted to the daytime period. No significant changes in the MAP acrophase were observed. In addition, ANG-(1-7) infusion produced a small but significant sustained bradycardia. ANG-(1-7) did not change cardiovascular responses to restraint stress. These data indicate that ANG II can influence the activity of brain areas involved in the determination of stress-induced or circadian-dependent variations of blood pressure without changing HR fluctuations. A significant modulatory influence of ANG-(1-7) on basal MAP and HR is also suggested.

Sexual intercourse and risk of ischaemic stroke and coronary heart disease: the Caerphilly study

OBJECTIVE

To examine the relation between frequency of sexual intercourse and risk of ischaemic stroke and coronary heart disease.

DESIGN

Cohort study with 20 year follow up.

SETTING

The town of Caerphilly, South Wales and five adjacent villages.

SUBJECTS

914 men aged 45-59 years at time of recruitment in 1979 to 1983.

MAIN OUTCOME MEASURES

Ischaemic stroke and coronary heart disease, all first events and fatal events.

RESULTS

Of the 914 men studied, 197 (21.5%) reported sexual intercourse less often than once a month, 231 (25.3%) reported sexual intercourse twice or more a week, and the remaining 486 (53.2%) men fell into the intermediate category. Frequency of sexual intercourse was not associated with all first ischaemic stroke events: age adjusted odds ratios (95% CI) for intermediate and low frequency of sexual intercourse of 0.61 (0.32 to 1.16) and 0.71 (0.34 to 1.49) respectively compared with the reference category of high frequency. A graded relation with fatal coronary heart disease events was observed in events recorded up to 10 years. The age adjusted relative risk (95% CI) of fatal coronary heart disease contrasting low frequency of sexual intercourse (that is, less than monthly) with the highest group (at least twice a week) was 2.80 (1.13 to 6.96, test for trend, p=0.04) which was not attenuated by adjustment for a wide range of potential confounders. Longer follow up to 20 years showed attenuation of this risk with odds of 1.69 (95% CI 0.90 to 3.20), contrasting low frequency of sexual intercourse with the highest group.

CONCLUSIONS

The differential relation between frequency of sexual intercourse, stroke and coronary heart disease suggests that confounding is an unlikely explanation for the observed association with fatal coronary heart disease events. Middle aged men should be heartened to know that frequent sexual intercourse is not likely to result in a substantial increase in risk of strokes, and that some protection from fatal coronary events may be an added bonus.