Understanding Your Cardiovascular Risk: ACC/AHA Risk Assessment Calculator and Insights

In the last 65+ years, numerous studies and meta-analyses were done and a plethora of pharmacological treatments were developed. A few dozen diets appeared in the last 100 years and the lifestyle of the modern man changed radically multiple times. When adding all this clinical experience with all the fundamental research that was done in the last decade, researchers were able to pretty accurately pinpoint the most prevalent risk factors for cardiovascular disease and ASCVD as well as to develop treatment strategies for mitigating CVD events, such as MI, HF or stroke. ^{[1], [8], [9]}

Even as cardiovascular diseases still kill the most people worlwide compared to other diseases, morbidity was greatly reduced in the last decades, and life expectancy had slowly risen since the last century.

Some of the most important predictors of cardiovascular diseases and events, based on the studies that served for the creation of the most used CVD risk scores, are: ^{[1], [4], [6]}

1. Age particulary if > 65 years old or >75 years old
2. Hypertension particularly, systolic blood pressure
3. Prior Stroke or MI ^[9]
4. Diabetes mellitus, active smoking
5. Male gender ^[8]
6. Total cholesterol, LDL and HDL levels ^[11]
7. African American or Hispanic descent ^[8]

Some of the most known and widely used risk prevention strategies are based on the following elements:

• Blood pressure lowering medications (usage of the 'polypill' is recommended, when appropriate, for optimisation of adherence)
• Lipid lowering medications ^[11]
• Dietary interventions particulary the Mediterranean diet, increasing fibre intake, nut consumption, reduced salt intake in patients with renal disease or carbohydrates in patients with diabetes mellitus and aggressive glycemic control
• Smoking cessation and alcohol consumption reduction to less than 14 units (one unit = 10gr. alcohol) per week irrespective of gender (NHS Alcohol guidelines)
• Physical exercise: 150 minutes of moderate-intensity physical activity and 2 days of moderate-high intensity -when appropriate - exercise per week
• Policy and legislative changes: food labeling, junk food taxation and subsidies, air pollution addressing, food and drink quality standards, health promotion-mass media campaigns a.o. ^{[1], [2]}

In conclusion, through decades of research and clinical experience, significant progress has been made in understanding and addressing cardiovascular health. By identifying prevalent risk factors and implementing effective prevention strategies, such as medication use, dietary interventions, lifestyle modifications, and policy changes, the burden of cardiovascular diseases and related events has been significantly reduced. However, it is crucial to continue promoting awareness and implementing evidence-based approaches to further improve heart health worldwide.

The Working Group of the AHA recognized the need for creating a tool that effectively assesses the risk of a patient developing cardiovascular events and estimates their mortality based on preventive measures and influencing risk factors ^[1]. However, it is important to acknowledge that despite the existence of such risk scores, they have limitations in accurately predicting the occurrence of heart attacks or strokes in individuals over a specific time frame. As stated,

It should be noted that only a fraction of patients, even those at high risk, will experience such events in their lifetimes, and not all strokes or heart attacks can be prevented through comprehensive surveillance or aggressive treatment strategies.

Nevertheless, the development of cardiovascular risk tools such as the Framingham risk score or QRISK has significantly aided cardiologists by allowing them to focus their efforts on high-risk individuals and gain a better understanding of the impact of risk factors and preventive measures on outcomes and quality of life. It has been demonstrated through various studies and meta-analyses that risk factors and their influence can vary considerably among different populations ^[8]. Thus, the ACC/AHA groups recognized the necessity of creating a new risk assessment tool specifically tailored to American patients, while also updating it to meet the needs of modern cardiologists, considering the evolving definition of myocardial infarction (MI) ^[8].

The Work Team made the decision to develop a new risk score and reevaluate existing evidence instead of recommending the Framingham score, which was widely used at the time (2013). This choice was influenced by the observation that the current score tended to provide inaccurate risk classifications for populations of African descent and other subgroups in America ^[9]. The Work Group also identified additional parameters that could enhance the precision of these scores, such as the inclusion of "previous stroke" as a risk factor.

It should be noted that while the risk score results are applicable to white and African American patients, their representation may not accurately predict risks in other populations, and further clinical examination may be necessary for accurate risk prediction ^[10]. Furthermore, the authors of the studies used to develop the score acknowledge that even if two patients have the same score value based on their risk factors, the presence of certain risk factors can still imply worse outcomes than others. For instance, a patient with hypertension may have worse outcomes compared to a patient with the same score but without hypertension, as hypertension is a significant risk factor for Atherosclerotic Cardiovascular Disease (ASCVD) ^{[2], [4], [9]}.

While multiple cohort studies and meta-analyses have confirmed the utility of major risk scores in triaging and managing patients with cardiovascular disease (CVD), atrial fibrillation (AF), and heart failure (HF), it is important to recognize the existence of discrepancies among these scores. It has been observed that these risk scores should not be solely relied upon but should be correlated with clinical data and other risk factors not considered by these scores, as suggested by recent studies. Furthermore, caution is advised when using these scores for patient populations not specifically recommended in the original studies. ^[1]

A study revealed that the ACC/AHA risk score tends to overestimate mortality rates across all risk categories. The authors demonstrated that both 5-year mortality and event rates were significantly lower than the predicted values, with the discrepancy being more prominent in lower risk categories (almost 3 times lower at risk scores <10% and almost 2 times lower at risk scores ≥10%). ^[6]

Another study found similar results but noted that the ACC/AHA risk score was not the most problematic. The ATP-III (Adult Treatment Panel III) score exhibited even greater discrepancies, while the RRS score (Reynolds Risk Score) provided the most accurate results, followed by the Framingham Risk Scores for CVD and CHD. ^[7]

When considering the initiation of statin treatment, the aforementioned discrepancies and tendency for overestimation become less relevant. However, caution should still be exercised when using the proposed 7.5% risk threshold for making decisions regarding prophylactic measures. Instead, healthcare providers should prioritize recommending lifestyle modifications such as dietary changes, exercise, and smoking cessation before considering pharmacological interventions, particularly when using the ACC/AHA or ATP-III scores.

In a small study involving 129 patients, a comparison between the ACC/AHA score and the QRISK Score demonstrated that while the QRISK score was easier to implement and had a higher applicability rate compared to the Framingham and ACC/AHA scores (which have specific cutoffs based on high cholesterol, systolic blood pressure, or age values), the ACC/AHA score exhibited superiority in predicting high-risk patients for CVD. ^[10] However, it is important to note that other studies have shown mixed results, and the QRISK score is actively maintained with updated versions, including QRISK 2 (2017) and QRISK 3 (2018), being developed since its initial introduction.