It is well known that stroke is one of the major diseases that endanger the health and life of middle-aged and elderly people, and is currently the second leading cause of human death. In the third national cause of death survey published by the Ministry of Health in 2008, stroke (136.64/100,000) has overtaken malignant tumors (135.88/100,000) as the number one cause of death in China.
At present, the incidence rate of stroke in China is 120-180/100,000, the prevalence rate is 400-700/100,000, the number of new cases is >2 million, the number of deaths is >1.5 million, the number of survivors is 6-7 million, and 2/3 of them have different degrees of disability, and the high morbidity, mortality, and disability rates impose a heavy burden on society and families. The best way to reduce the burden of stroke is through prevention, especially primary prevention, which is the active and early intervention of stroke risk factors to reduce the incidence of stroke.
In addition, in December 2013, a guideline from the Joint National Committee 8 (JNC 8) and the AHA/ACC was issued to manage and control hypertension to reduce the risk of cardiovascular disease and complications. Each of these guidelines may reduce the burden of stroke to varying degrees, and although the release of these guidelines represents a great advance, it is not without its share of skepticism.
New recommendations and changes in practice guidelines
1. New guidelines for cardiovascular risk assessment
On November 12, ACC and AHA jointly published the “2013 ACC/AHA Guidelines for Cardiovascular Risk Assessment”. The guidelines focus on the 10-year risk of atherosclerosis-related events as the primary concern, and no longer emphasize the achievement of individual indicators such as cholesterol. The guidelines also provide additional formulas for risk prediction and suggest methods for identifying individuals at risk in different populations and key interventions.
Some scholars have questioned the ACC/AHA approach to cardiovascular disease risk assessment, arguing that it overestimates the risk of disease by 75-150% and will result in most patients receiving unnecessary statin therapy, but with 1/3 of the world’s population dying from cardiovascular disease and 60% experiencing cardiovascular events, it is reasonable for the guidelines to recommend statins for potentially at-risk populations.
For our country, this risk assessment model should be calibrated and the cohort should be restudied to create a predictive model based on our population for effective prevention. Despite the controversy of the guidelines, there are many conceptual advances, the most important being the de-emphasis on individual risk factors and a focus on the patient as a whole, with the goal of reducing overall risk. Notable changes from previous guidelines are the endorsement of specific models for overall risk assessment and the diminished role of measuring CIMT.
2. Lipid lowering
The new guidelines simplify the lipid-lowering regimen, emphasizing the use of statin therapy because there is less evidence that non-statin drugs reduce cardiovascular events or stroke; in the new guidelines, the goal is no longer to treat LDL cholesterol because of the overall lack of evidence and concerns about adverse events.
The most significant changes from the 2004 update of the ATP3 guidelines are that it is up to the physician to determine which of the four categories a patient falls into, to treat with moderate- or high-intensity statins, rather than adjusting drug doses to meet LDL cholesterol treatment goals, and to test lipids during follow-up to assess adherence to treatment, rather than to see if LDL cholesterol-specific Treatment goals.
The following four groups should receive statin therapy.
① Patients with clinical atherosclerotic cardiovascular disease (ASCVD) should receive high-intensity (age < 75 years) or moderate-intensity (age ≥ 75 years) statin therapy.
②Patients with LDL cholesterol levels ≥190 mg/dL should receive high-intensity statin therapy.
(iii) Patients with diabetes mellitus aged 40-75 years with LDL cholesterol levels of 70-189 mg/dL and no clinical ASCVD should receive at least moderate-intensity statin therapy (and possibly high-intensity statin therapy if the estimated 10-year risk of ASCVD is ≥7.5%).
④ Patients without clinical ASCVD or diabetes but with LDL cholesterol levels of 70-189 mg/dL and an estimated 10-year risk of ASCVD of ≥ 7.5% should receive moderate or high-intensity statin therapy. For some individuals who are not eligible for statin therapy in groups 1-4, other factors such as high-sensitivity C-reactive protein (hs-CRP), coronary artery calcification score (CAC) score, and ankle-brachial index (ABI) should be considered to assist physicians in making treatment decisions.
This guideline differs from the previous National Cholesterol Education Program Adult Treatment Panel Criteria, Third Edition (NCEP ATP III ), rather than overall ASCVD risk, with treatment protocols based on the cardiovascular risk assessment system of the Framingham Heart Study results, coronary heart disease risk factors or equivocal conditions for coronary heart disease, LDL-C baseline levels, and, in contrast to the new guideline, ATP III incorporates specific LDL-C treatment targets.
Both ATP III and the new guidelines recommend statins for the treatment of coronary heart disease or other high-risk conditions, such as diabetes or symptomatic carotid atherosclerosis. In these groups, statin therapy reduces the risk of a first-time will stroke by about 20%. The new guidelines also expand the application of statin therapy (no ASCVD, 10-year predicted risk of cardiovascular events ≥7.5% in patients with diabetes).
3. Blood pressure control
JNC 8 recommends a blood pressure lowering goal of <150/90 mm Hg for older adults aged ≥60 years (strongly recommended, Class A) and a blood pressure lowering goal of <140/90 mm Hg based on expert opinion and clinical circumstances (e.g., treatment systolic blood pressure goal of <140 mm Hg has been achieved and is tolerated by the patient).
The scientific recommendations issued by the ACC/AHA/CDC state that the definition of hypertension as systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg is consistent with previous values of hypertension levels defined by the JNC7/8. For pharmacological treatment, a thiazide diuretic ((hydrochlorothiazide) and an additional angiotensinase converting enzyme inhibitor (ACEI) (lenopril: except for women of childbearing age) are recommended for initial treatment in all age groups.
For patients with chronic kidney disease or diabetes, the antihypertensive goal is <140/90 mm Hg (based on expert opinion, level E); for the general population except blacks (including diabetics); initial antihypertensive therapy should include a thiazide diuretic, a calcium antagonist (CCB), an angiotensin-converting enzyme inhibitor (ACEI), or an angiotensin receptor antagonist (ARB) (moderate recommendation , grade B).
For blacks in general (including diabetics), initial antihypertensive therapy includes thiazide diuretics or angiotensin receptor blockers (CCB) (blacks in general: moderate recommendation, grade B; blacks with diabetes: mild recommendation, grade C); beta-blockers are not recommended as initial therapy or in combination with CCEI and CCB.
Concerns
As noted above, the ACC/AHA guideline developers acknowledge that the Global Prediction Calculator may overestimate risk because it may not apply to certain racial and ethnic populations, including Hispanics, Asians, or American Indians, which will likely lead to overuse of statins as primary prevention. This is an important issue because when statins are overused, they are not beneficial for some populations, such as isolated heart failure, renal insufficiency. Or for some specific clinical situations, clinical data can be directly applied for lipid-lowering therapy.
In contrast to the ACC/AHA/CDC scientific recommendations, JNC8 deviates from the long term reduction target of <140/90 mm Hg. The relationship between blood pressure and stroke risk persists at levels ≥115/75 mm Hg. JNC8 recommends a target value of <150/90 mm Hg for blood pressure control as an imprudent approach, which may increase the prevalence of stroke in the population. The discrepancy between the scientific recommendations of the AHA/CDC and JNC 8 for blood pressure control goals and treatment can be confusing to health care providers, taxpayers, and the public.
Additional Implications for Stroke Prevention
The new guidelines include stroke as the primary ASCVD outcome endpoint, regarding stroke prevention (primary or secondary prevention) and type (hemorrhagic or ischemic stroke subtype), and they do not specifically address the status of statin therapy or blood pressure control goals. The use of statins in high-risk populations (ASCVD and diabetic patients) reduces the risk of stroke, but the role of primary stroke prevention in other populations is unknown.
Based on a recent Meta-analysis, the use of statins for primary prevention of CVD, including those with risk factors and low risk, significantly reduced stroke events by 22%, all-cause mortality by 14%, fatal and nonfatal cardiovascular events by 25%, and fatal and nonfatal coronary events by 27%. These provide evidence for the widespread use of statins in different populations. Statins are currently not indicated in patients with cardiogenic stroke because they do not meet the new ACC/AHA criteria for statin administration.
Hypertension is the single most important and controllable risk factor in stroke prevention, and it has been discussed that there is no J-type relationship between blood pressure and vascular risk factors for first stroke, although low systolic and diastolic blood pressure may lead to cardiovascular complications in the general population but not stroke complications. In the United States, most stroke-related disease mortality has been reduced over the past few decades thanks to control of blood pressure levels in the population, and it is important to set specific reduction targets for the prevention of first or recurrent stroke.
The current AHA secondary stroke prevention guidelines are unclear regarding BP reduction targets and the degree of BP reduction, and for such patients, a BP reduction target of <140/90 mm Hg is considered. results from the Secondary Prevention of Subcortical Stroke in Small Cortical Stroke study suggest that a BP reduction target of <130 mm Hg is safe and may be beneficial in patients with recent lacunar cerebral infarction. The new guidelines are critical for clinical decision making, but still have their inherent limitations and different treatment options should be made depending on the specific situation.