Stroke Flashcards
What is a stroke?
An acute, rapidly-developing focal neurological dysfunction due to an abnormal perfusion of brain tissue, resulting in cellular death (infarction).
In other words, stroke is all about interruption of the normal blood supply to the brain (ischemia), resulting in neuro dysfunction and the death of brain cells. emphasis on imaging and neurological deficits and de-emphasis of temporal aspects for former definitions (i.e., ≥ 24 hours). Included in the definition of stroke, in addition to cerebral infarctions, are spinal and retinal infarctions.
Clinically, “stroke” continues to typically be used to refer to cerebral infarctions.
Define ischemic stroke and prevalence
Ischemic: due to thrombosis, embolism, or systemic hypoperfusion. About 87% of all strokes are ischemic.
Most common site is the middle cerebral artery (MCA)
Transient ischemic attacks (TIA) are an important warning sign.
“Cardioembolic”: includes A-Fib, ventricular thrombus, prosthetic valves, rheumatic heart disease, other cardiac sources.
Define the two types of hemorrhagic strokes, prevalence, and what to call them
Subarachnoid hemorrhage (SAH), about 3%
Bleeding in the subarachnoid space
Intracerebral hemorrhage (ICH), about 10%
Bleeding inside the brain
AHA/ASA discourages use of the term “hemorrhagic stroke” for its lack of specificity
Who has a stroke?
Females have a higher lifetime incidence than males – approximately 1 in 5 for females 55 to 75 years old and 1 in 6 for males in the same age group.
At younger ages, this is reversed, with males having a higher incidence of stroke.
Age-adjusted incidence of first ischemic stroke per 1,000 population is 0.88 in non-Hispanic whites, 1.91 in blacks, and 1.49 in Hispanics.
Age itself is a major risk factor for stroke, with nearly 3/4 of all strokes occurring in in people over age 65. 17% of all strokes occur in people over age 85.
Who dies from a stroke?
The age-adjusted death rate for non-Hispanic black Americans in 2015 was 52.2 per 100,000, and for non-Hispanic white Americans it was 36.4 /100,000; the ratio is approximately 1.4:1).
People living in the southern state “stroke belt” (NC, SC, GA, TN, MS, AL, LA and AR) have a stroke mortality about 20% higher than the rest of the US. The “stroke belt buckle” of coastal NC, SC and GA has a stroke mortality rate 40% higher than the rest of the US.
Mortality increases with age: about 10% < 65, 20% between 65-74, 30% between 75-84 and 40% ≥ 85
Roughly 25% of people over age 65 will die within a year of their first stroke.
Roughly 50% of people over age 65 will die within 5 years of their first stroke.
What is happening to the stroke rate and why?
The decline is due to a decrease in both stroke incidence and stroke mortality.
AHA/ASA attributes the decline to improved BP control, as well as reduced smoking, improved DM control and improved lipid control (Lackland et al., 2014).
What are causes of stroke?
Thrombus within cerebral vasculature
Usually starts when atherosclerotic plaque becomes unstable, similar to MI.
Embolus, usually of cardiac or carotid origin
Large cerebral artery occlusion is typically embolic
Atrial Fibrillation
Valvular thrombi: mitral stenosis, endocarditis or prosthetic valve
http://watchlearnlive.heart.org/CVML_Player.php?moduleSelect=iscstr
Small vessel disease (e.g., lacunar infarct)
Hypoperfusion (low BP state, ↓ cerebral perfusion pressure)
Hyperviscous blood
Sickle Cell Disease
Polycythemia Vera
Cryptogenic
Define and explain cryptogenic stroke
= ischemic stroke for which no probable cause is identified after adequate diagnostic evaluation.
Is a Dx of exclusion
20-30% of all ischemic strokes designated cryptogenic after standard work up:
MRI or CT of brain
CTA or MRA of brain, neck and thoracic arteries; ultrasound if CTA and MRA contraindicated or unavailable
TTE, TEE
ECG, Holtor monitor, 30-day event monitor, loop recorder
Hematologic testing for hypercoagulable states
Occult “low burden” paroxysmal AF may be found: significance unclear
Patent foramen ovale (PFO) may be found
What are “nonmodifiable” risk factors for stroke?
Age – single most important non-modifiable factor
Sex (higher lifetime incidence older females > older males)
Race and ethnicity (AA, Latino, Native Americans > non-Latino white, Asian)
Sickle cell disease
Family history
An ischemic stroke in either parent by the age of 65 is associated with a 3-fold increase in the risk of ischemic stroke in offspring. Importance of taking a good family history!
A prior stroke or TIA puts you at increased risk for a subsequent stroke.
Cumulative risk of a stroke in the 5 years after an initial stroke is roughly 25%.
Cumulative risk of a stroke, ACS, or CVD death in the 5 years after a TIA is roughly 13%. (Amarenco et al., 2018)
What are modifiable risk factors for stroke?
General rule: The things that keep our patients’ hearts healthy will also keep their brains healthy.*
- Evidence regarding cholesterol is not as clear in stroke prevention as it is in MI prevention.
1. Hypertension
2. Diabetes
3. Atrial fibrillation
4. Other cardiac morbidities including HF
5. Carotid Artery Stenosis
6. HLD (?)
7. smoking
8. Heavy ETOH use
9. physical inactivity
10. CKD
11. “Obesity” (?)
12. Sleep apnea
Discuss HTN and stroke
About 3/4 of those who have a first stroke have BP > 140/90. Diabetics with BP < 120/80 have half the lifetime risk of stroke compared with people with HTN (not just just diabetics with HTN)
Discuss DM and stroke
DM more than doubles the risk for ischemic stroke
DM particularly increases the risk of a stroke at a younger age: < 55 y.o. for blacks and < 65 y.o. for whites.
Duration of DM matters, esp. in pts. with AF. Longer duration greater risk of ischemic stroke.
Discuss afib and stroke
AF independently increases the risk of stroke about 5-fold at all ages. AF causes about 1.5% of strokes in age 50 to 59, but about 23.5% at 80 to 89. It is likely these are underestimates, because AF is often asymptomatic and undetected. note that the incidence of AF itself increases with age, so this plays a significant role in the age-related increase in AF-induced stroke.
Females with AF have approx. double the relative risk of having a stroke as males. Reasons for this are unclear.
Other cardiac morbidities increase the risk of stroke. In older adults, HF is associated with a 4-fold increase in stroke risk.
What is the left atrial appendage and why is it key?
In non-valvular afib, over 90% of stroke is caused by blood clots that form in the LAA
Discuss Carotid Artery Stenosis and Stroke risk
Greater degrees of stenosis are associated with greater stroke risk. In general, CAS doubles the risk of a stroke.
Discuss HLD and stroke risk
Data is not completely settled; the effect of total cholesterol seems to wane with age. Most studies have found high total cholesterol to be a risk factor for ischemic stroke, but the relationship is not strong – especially in people over age 75 – and other studies contradict. Effect of HDL-C on stroke risk is not clear.
Discuss smoking and stroke risk
Current smokers have a risk for stroke 2 to 4 times greater than nonsmokers and those who quit > 10 years ago.
Is the most important modifiable risk factor in preventing SAH
Discuss ETOH use and stroke risk
Key is “heavy,” because low and moderate use of alcohol is associated with decreased risk of stroke.
The National Institute on Alcohol Abuse and Alcoholism defines heavy drinking for a man as >4 drinks in any single day or >14 drinks per week and defines heavy drinking for a woman as >3 drinks any single day and >7 drinks per week. A standard drink is defined as 12 fl oz of regular beer, 5 fl oz of table wine, or a 1.5–fl oz shot of 80-proof spirits.
Discuss physical inactivity and stroke risk
Moderate to vigorous physical activity is associated with a 35% reduction in the risk of ischemic stroke.
Discuss CKD and stroke risk
Creatinine ≥ 1.5 mg/dL or GFR < 60 are both associated with greater stroke risk.
Proteinuria and albuminuria are better predictors of stroke risks than eGFR in patients with existing kidney disease.
Discuss the role of “obesity” and stroke risk
In BMI range of 25 to 50 kg/m2 there is a 40% increased stroke mortality with each 5-kg/m2 increase in BMI.
However, “There is no clear and compelling evidence that weight loss in isolation reduces the risk of stroke because of the difficulty in isolating the effects of weight loss as a single contributing factor rather than as a component contributing to better control of hypertension, diabetes mellitus, metabolic syndrome, and other stroke risk factors.” Meschia et al. (2014).
Discuss the role of sleep apnea and stroke risk
Increases the risk of stroke 2-fold. The risk increases with the severity of the apnea.
Relationship is bi-directional: Sleep apnea is common after stroke and CPAP reduces the risk of recurrent vascular events.
What are some modifiable risks specifically related to people able to get pregnant or with estrogen as dominant hormone?
Migraine with aura (> common in females than males), doubles risk for ischemic stroke, esp. in younger females.
Use of oral contraceptives, estrogen plus progestin or estrogen alone
Use of hormone replacement therapy (estrogen alone or progestin/estrogen in combo) in post-menopausal females associated w/increased stroke risk
FYI, pregnancy and the first six weeks post-partum raise the risk of ischemic stroke or ICH to a rate 2.4 times greater than for pregnant females of similar age and race.
What primary care interventions should be done for modifiable risk factors?
Hypertension – screen and treat!
Diabetes – screen and treat!
Atrial fibrillation – screen and probably refer (but anticoagulate meanwhile)!
Carotid stenosis – screen! U/S, depending!
Smoking – keep bringing it up! Assist w/cessation!
Sleep Apnea – Ask! Epworth Sleepiness Scale! Sleep study!
CKD – track that albuminuria!
Alcohol use disorder – Screen! Refer!
What are general guidelines for primary prevention of stroke according to 2014 American Heart Association/American Stroke Association Guidelines for the Primary Prevention of Stroke?
Obtain a complete family history
Screen everyone for their stroke risk with a validated tool such as the Modified Framingham Stroke Risk Profile, or ACC/AHA ASCVD Risk Estimator https://tools.acc.org/ascvd-risk-estimator-plus/#!/calculate/estimate/
Treat HTN to keep BP < 140/90 (*but individualize to pt. )
Encourage pts. who do not smoke to never start, and help pts. who do smoke to stop smoking with a combo of counseling and medication.
What are stroke-prevention DM recommendations?
BP control as above. Use of an ACEI or an ARB.
Statin is recommended. However, adding a fibrate to a statin has not been shown to decrease stroke risk and is “not useful”.
AHA/ASA guideline is silent on specific glycemic targets, noting that there is a “lack of convincing support from any individual clinical trial for intensified glycemic control to reduce stroke incidence in patients with diabetes mellitus”
Some evidence that getting BG under control in Type 2 DM patients with BMI > 30 has a protective effect.
ADA Standards of Medical Care in Diabetes (2019) also do not make a strong link between specific glycemic targets and stroke.
Primary prevention with HLD?
Lifestyle changes + treatment with a statin recommended for patients with a high 10-year ASCVD risk.
No good evidence that fibrates, nor niacin nor other lipid-lowering therapies decrease the risk of stroke.
Afib and primary prevention?
Screen everyone > 65 for AF (pulse plus ECG if indicated)
In non-valvular AF, anticoagulation for all pts. at high risk:
For most patients a DOAC/NOAC (Direct-acting Oral Anticoagulant/ Non-Vitamin K Antagonist Oral Anticoagulant), including dabigatran (Pradaxa) or apixaban (Eliquis), rivaroxaban (Xarelto) or edoxaban (Savaysa) is preferred over warfarin.
For those w/non-valvular* AF at moderate risk, any of: no antithrombotic** therapy, anticoagulation, or aspirin “may be considered”.
For those at low risk, aspirin is no longer recommended.
What is the Watchman?
Approved by FDA in 2015 for nonvalvular A-Fib in patients who “have an appropriate rationale to seek a non-pharmacologic alternative to warfarin. “
“Noninferior” or “comparable” to warfarin in 5-year follow-ups.
Not part of any guideline recommendations.
CMS covers the device as of February 2016, with strict criteria.
How can you determine risk level with AF patients?
CHA2DS2-VASc criteria:
Congestive heart failure: 1 point Hypertension: 1 point Age 65 to 74: 1 point Age ≥ 75: 2 points Diabetes: 1 point Stroke or TIA: 2 points Sex (female): 1 point Vascular disease (MI, PAD or aortic plaque): 1 point
Low risk: 0 points if male, 1 point if female
Moderate risk: 1 point if male, 2 points if female
High risk: ≥ 2 points if male, ≥ 3 points if female.
Most of our older adult patients with AF will be HIGH RISK!
Primary prevention, carotid artery stenosis
Asymptomatic patients should be treated with aspirin + statin
Selection of patients for revascularization is dependent on comorbidities, life expectancy and other individual factors
Reasonable to consider performing carotid endarterectomy (CEA) in asymptomatic patients who have >70% stenosis of the internal carotid artery if the risk of perioperative stroke, MI, and death is low (<3%). However, its effectiveness compared with medical management alone is not well established.
Prophylactic CEA may be performed in highly selected patients (minimum 60% stenosis on angiography, 70% on Doppler ultrasound), but its effectiveness compared with medical therapy alone in this situation is not well established.
In asymptomatic patients at high risk of complications for carotid revascularization by either CEA or CAS, the effectiveness of revascularization versus medical therapy alone is not well established.
Primary stroke prevention, migraine with aura
Smoking cessation
Tx to reduce migraine frequency “might be reasonable”
Rec for diet/nutrition
A Mediterranean diet supplemented with nuts “may be considered”
Recs for physical activity
moderate- to vigorous-intensity aerobic physical activity at least 40 min/day, 3 to 4 days/week
