The goals of the American College of Cardiology (ACC) and the American Heart Association (AHA) are to prevent cardiovascular (CV) diseases, improve the management of people who have these diseases through professional education and research, and develop guidelines, standards and policies that promote optimal patient care and cardiovascular health. Recommendations are derived from randomized trials, meta-analyses, and observational studies evaluated for good quality.
The Expert Panel was charged with updating the clinical practice recommendations for the treatment of blood cholesterol levels to reduce atherosclerotic cardiovascular disease (ASCVD) risk using data from randomized controlled trials (RCTs) and systematic reviews and meta-analyses of RCTs. ASCVD includes coronary heart disease (CHD), stroke, and peripheral arterial disease, all of presumed atherosclerotic origin. The recommendations are intended to provide a strong evidence-based foundation for the treatment of cholesterol for the primary and secondary prevention of ASCVD in women and men the great cause of morbidity and mortality worldwide including South Africa.
The summary of the guidelines are:
1. Focus on ASCVD Risk Reduction: 4 statin benefit groups: based on a comprehensive set of data from RCTs that identified 4 statin benefit groups which focus efforts to reduce ASCVD events in secondary and primary prevention. Identifies high-intensity and moderate-intensity statin therapy for use in secondary and primary prevention.
2. A New Perspective on LDL–C and/or Non-HDL–C Treatment Goals: The Expert Panel was unable to find RCT evidence to support continued use of specific LDL–C and/or Non-HDL targets. The appropriate intensity of statin therapy should be used to reduce ASCVD risk in those most likely to benefit. Non Statin therapies do not provide acceptable ASCVD risk reduction benefits compared to their potential for adverse effects in the routine prevention of ASCVD.
3. Global Risk Assessment for Primary Prevention: The guideline recommends use of the new Pooled Cohort Equations to estimate 10-year ASCVD risk in both white and black men and women. By more accurately identifying higher risk individuals for statin therapy, the guideline focuses statin therapy on those most likely to benefit. It also indicates, based on RCT data, those high-risk groups that may not benefit. Before initiating statin therapy, this guideline recommends a discussion by clinician and patients.
4. Safety Recommendations: The guideline used RCTs to identify important safety considerations in individuals receiving treatment of blood cholesterol to reduce ASCVD risk. Using RCTs to determine statin adverse effects facilitates the understanding of the net benefit from statin therapy. Provides expert guidance on management of statin-associated adverse effects, including muscle symptoms.
5. Role of Biomarkers and Noninvasive Tests: Treatment decisions in selected individuals who are not included in the 4 statin benefit groups may be informed by other factors as recommended by the Risk Assessment working Group guideline.
6. Future Updates to the Blood Cholesterol Guideline: The comprehensive guideline is for the evidence-based treatment of blood cholesterol to reduce ASCVD risk. Future updates will build on this foundation to provide expert guidance on the management of complex lipid disorders and incorporate refinements in risk stratification based on critical review of emerging data. RCTs comparing alternate treatment strategies are needed in order to inform future evidence-based guidelines for the optimum ASCVD risk reduction approach.
The move away from a singular focus on LDL levels, with an emphasis on treating RISK instead of LDL level is refreshing as we are very familiar with some individuals with ADVANCED ASCVD with essentially “normal” LDL levels. The lipid hypothesis is not being impugned in any matter or form, but we are realizing that pursuing targets at all costs may lead to the use of medications and or strategies that are not known to benefit patients.
Second, the emphasis on proven medications is extremely important. We have learned that not all medications that favourably affect lipids result in risk reduction for patients. We have learnt this from hormone therapy in postmenopausal women where whilst the lipogram may improve favourably on “paper” the risk of the woman may actually worsen. We have very poor results with the HDL elevating drugs confirmed in RCT’s to worsen prognosis and there are may “naturopathic” agents that have absolutely no evidence-base to reduce ASCVD.
So we can use lipids to understand risk, but just because a medication improves a lipid profile does not mean that it has reduced the risk of heart attacks or dying of vascular disease. So the guidelines suggest moving away from LDL and emphasised the use of proven medications to reduce risk – and statins are the class that has been shown most conclusively to reduce risk. Moreover, they reduce risk regardless of the LDL level. Also, the trials tested the drug – not a strategy based on a target. So the guidelines de-emphasize non-statins, like ezetimibe, and emphasise the Statin class.
The guidelines direct attention to RISK STRATIFICATION. I have advocated this approach for over a two decades and whist there may be controversy over the risk calculator to use – and the threshold that makes it worth it to receive treatment – the principle of being cognizant of the size of the potential benefit will endure. Work is still needed as to what tools best define a person’s risk of ASCVD but ultimately the decision about whether treatment is worthwhile should reside with a patient who is informed about the risks and benefits. We do need to be sure we are accurately estimating risk and finding ways to communicate information about the decision to patients, but we should not impose a decision on patients. It is up to us to include the patient in all decision-making.
Cardiovascular risk stratification I believe is more than just plugging values (age; sex; race group; total cholesterol; HDL cholesterol; systolic blood pressure; smoking history; diabetes history) into a risk calculator but includes the genetic risk of an individual as family members with premature vascular events (males < 55 years and females < 65 years) significantly increase an individuals risk. Biological markers of risk with ultra sensitive C reactive protein (us-CRP) and the “metabolic syndrome” influence risk tremendously. Finally any individual with “sub clinical” vascular disease risk stratifies into a POOR future prognostic category and would warrant Statin therapy despite normal LDL values.
One of the important strengths of the “new risk calculator” (http://my.americanheart.org/cvriskcalculator and http://www.cardiosource.org/science-and-quality/practiceguidelines-and-quality-standards/2013-prevention-guideline-tools.aspx for risk equations), is that it calculates your LIFETIME risk of ASCVD and how you compare to the “God-given” individual of your age/sex with optimal risk reduction. This provides really good insight into your future risk for vascular events and where you could target the most benefit in reducing risk for lifetime events.
I am really encouraged the movement away from lab cholesterol values, the emphasis on proven medications (Statins) and the emphasis on treatment for those with the most to gain are terrific aspects of the guidelines. Now is the time to turn to implementation and tools. We do need to determine what is the best way to estimate risk to risk stratify more accurately and communicate it with patients. And most importantly, we need to learn how best to engage patients in the decision. But the guidelines have laid out some important principles to guide the development of these tools – and ultimately help us all to make wiser decisions about prevention.