Coronary artery disease (CAD) affects one in 20 adults over the age of 20 years in the US and is the leading cause of death both within the US and globally.1 Approximately 805,000 individuals in the US have an MI each year, and nearly 25% of MIs occur in individuals who have had a prior MI.1 Although post-MI survival and rates of early recurrent MI (within the first year) have improved significantly since the 1970s due to advances in percutaneous coronary intervention (PCI) and medical therapy, recurrent coronary events remain an important clinical concern.2,3 Thus, secondary prevention through the optimization of cardiovascular health is key. Essential to this strategy is risk factor modification through medications, smoking cessation, nutrition, and physical activity. This review will provide a comprehensive summary of the above with a special focus on pharmacotherapy, lifestyle modifications, and cardiac rehabilitation (CR) in patients after MI or PCI.
Pharmacotherapy After Revascularization
After PCI for stable ischemic heart disease (SIHD) or in the setting of MI, several medications should be initiated to improve mortality and reduce the risk of a recurrent atherothrombotic event. The cornerstone of medical therapy post-PCI is platelet inhibition with dual antiplatelet therapy (DAPT), consisting of aspirin and a P2Y12 inhibitor.4 With respect to the P2Y12 inhibitor, prasugrel or ticagrelor may be preferable to clopidogrel for the reduction of stent thrombosis.5 DAPT is generally recommended for a minimum of 12 months for an acute coronary syndrome (ACS) event and a minimum of 6 months for SIHD treated with PCI, barring any contraindications.5,6 Some studies, however, have challenged this recommendation due to concerns about bleeding. In a systematic review evaluating more than 79,000 patients who underwent PCI with a drug-eluting stent, a shorter duration of DAPT (<6 months) followed by P2Y12 inhibitor monotherapy versus 12 months of DAPT was associated with less bleeding events and was non-inferior with respect to MI, major adverse cardiovascular events (MACE), and mortality.7 A meta-analysis assessing the duration of DAPT after ACS treated with PCI found that a shorter duration of 1 to 3 months of DAPT followed by monotherapy with a P2Y12 inhibitor resulted in fewer bleeding events and a similar frequency of major adverse cardiac events when compared to DAPT for a 12-month duration.8 Ultimately, the optimal duration of DAPT should be individualized to each patient, weighing the individual risk for a recurrent atherothrombotic event versus a major bleeding event.
There is a clearly demonstrated benefit of β-blocker use for patients who experience an MI and have known heart failure with left ventricular ejection fraction (LVEF) ≤40% or ventricular arrhythmias.9,10 Therefore, a β-blocker should be recommended for these patient groups. However, a recent trial of patients with acute MI and preserved LVEF demonstrated that early initiation of β-blocker treatment versus no β-blocker use did not lead to a lower risk of death from any cause or new MI.11 Similarly, for patients who are post-PCI with SIHD and normal LVEF, β-blocker use has not been associated with improved cardiovascular outcomes, and the 2021 guideline for coronary artery revascularization gives β-blockers a class 3 recommendation (no benefit) in this group.5,12
After an MI or PCI for SIHD, high-intensity statins should be started with the goal of reducing LDL cholesterol (LDL-C) by at least 50% to a target goal of <70 mg/dl.6,13 The connection between LDL-C and atherosclerotic cardiovascular disease has been extensively evaluated and established through animal studies, epidemiological studies, and randomized controlled trials.13,14 Even lowering LDL-C by 1 mmol/l via statin therapy has been shown to reduce major coronary events, revascularizations, and ischemic strokes by almost 20%.15 Additionally, when compared to moderate-intensity statins, high-intensity statin therapy has been shown to further reduce LDL-C levels and major vascular events by 15%.16
If the LDL-C goal is not met on the highest tolerated statin therapy, additional lipid-lowering therapies such as ezetimibe and proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors can be considered.13 In the IMPROVE-IT trial, patients with a recent ACS event who received ezetimibe in addition to a moderate-intensity statin versus statin monotherapy lowered their LDL-C by 24% and experienced a 2% absolute risk reduction in the primary end point of death from cardiovascular disease, major coronary event, or non-fatal stroke at 7 years.17 Although rates of all-cause mortality did not differ between groups in the 2015 IMPROVE-IT trial, a recent national cohort study found that early usage of ezetimibe after ACS was associated with a 23% mortality reduction.18 Therefore, ezetimibe is the preferred initial additional agent due to its lower cost, wider availability, and proven safety profile, followed by a PCSK9 inhibitor. Two large, multicenter randomized controlled trials evaluated the efficacy of PCSK9 inhibitors in patients with a history of acute MI when added to maximally tolerated statin therapy.19,20 In the ODYSSEY OUTCOMES trial, the group receiving alirocumab experienced a 15% lower likelihood of developing death from CAD over a 2.8-year follow-up period compared to the placebo group. Participants in the FOURIER trial who received evolocumab versus placebo experienced a 15% reduced risk of cardiovascular death, myocardial infarction, stroke, hospitalization for unstable angina, or coronary revascularization over 48 weeks.
For select statin-intolerant individuals, bempedoic acid has emerged as an alternative for LDL-C reduction. In the CLEAR Outcomes Trial, among patients with a primary or secondary indication for lipid-lowering therapy who were unable or unwilling to take a statin, bempedoic acid resulted in a 21% LDL-C reduction and a 13% reduction in the primary end point of death from cardiovascular causes, nonfatal MI, nonfatal stroke, or coronary revascularization when compared to placebo.21
In addition to controlling LDL-C, hypertriglyceridemia is another important risk factor to address given its association with increased risk for ischemic events. The JELIS study demonstrated a 19% reduction in major coronary events in those taking low-intensity statins with 1.8 g of eicosapentaenoic acid daily versus low-intensity statin monotherapy over a mean follow-up of 4.6 years.22 Subsequently, REDUCE-IT focused on a highly purified EPA, icosapent ethyl. Patients with established cardiovascular disease and relatively stable LDL-C levels but elevated fasting triglyceride levels of 135–499 mg/dl despite statin therapy experienced a 25% reduction in the primary endpoint of cardiovascular death, nonfatal MI, nonfatal stroke, coronary revascularization, or unstable angina when taking 2 g of icosapent ethyl twice daily compared to placebo over 4.9 years.23
In post-MI patients with additional comorbidities such as heart failure with LVEF <40%, diabetes, hypertension, or chronic kidney disease, additional therapy with an angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker has been shown to improve outcomes.24 In the GISSI-3 trial, initiation of lisinopril versus placebo within 24 hours of an acute MI resulted in a 12% reduction in overall mortality, with a sustained benefit for up to 6 months even if lisinopril was discontinued.25,26 Other trial data demonstrated that the use of ACE inhibitors in patients with recent MI and reduced LVEF reduced the risk of mortality by up to 25% when compared to placebo.27,28 Moreover, angiotensin receptor/neprilysin inhibitors have demonstrated superiority to ACE inhibitors with respect to improving mortality in patients with heart failure, regardless of etiology.29 The addition of mineralocorticoid receptor antagonists such as eplerenone also significantly reduces cardiovascular mortality in those with acute MI even in the absence of heart failure when compared to placebo.30
Prescribing a sodium–glucose co-transport 2 (SGLT2) inhibitor or glucose-like peptide-1 (GLP-1) receptor agonist should also be considered for patients after MI or PCI. The efficacy and safety of SGLT2 inhibitors with respect to cardiovascular outcomes has been studied extensively. The EMPA-REG OUTCOME trial demonstrated that compared to placebo, empagliflozin led to a 14% reduction in the primary outcome of death from cardiovascular causes, nonfatal MI, or nonfatal stroke in diabetic patients at high risk for cardiovascular disease.31 A meta-analysis that incorporated data from EMPA-REG OUTCOME, CANVAS, and the DECLARE-TIMI 58 trial showed that SGLT2 inhibitors were associated with an 11% reduction in major adverse cardiac events in diabetic patients with established atherosclerotic disease.32 SGLT2 inhibitors are generally well tolerated but are associated with an increased risk of mycotic genital infections and diabetic ketoacidosis, albeit at low rates. An increased risk of lower limb amputations with the use of the SGLT2 inhibitor canagliflozin was observed in the CANVAS trial but this finding was not duplicated in the CREDENCE trial or noted in trials of other SGLT2 inhibitors.32,33
GLP-1 receptor agonists are also very beneficial in patients with cardiovascular disease, both with and without diabetes. A meta-analysis of GLP-1 receptor agonists in diabetic patients demonstrated a 14% reduction in MACE and a 12% reduction in all-cause mortality when compared to placebo. Additionally, the analysis found no increased risk for severe hypoglycemia, retinopathy, or pancreatitis with the use of GLP-1 receptor agonists.34 Moreover, in the SELECT trial, overweight or obese patients with preexisting cardiovascular disease but without diabetes who received the GLP-1 receptor agonist semaglutide experienced a 20% reduction in a composite primary endpoint of death from cardiovascular causes, nonfatal MI, or nonfatal stroke compared to placebo.35
Smoking Cessation
Smoking is a major cardiovascular risk factor associated with atherothrombotic disease and is the most common preventable cause of death worldwide.36 After MI or PCI for SIHD, smoking cessation is important for the prevention of reinfarction and stent thrombosis.5 Moreover, the post-MI or post-PCI period is an optimal time to focus on smoking cessation as a secondary prevention strategy to improve mortality and quality of life. A population-based cohort study demonstrated that individuals who quit smoking after their initial MI experienced a 37% lower mortality risk compared to those who continued smoking over a 13-year follow-up period.37 For patients who are unable to quit smoking, reducing the number of cigarettes smoked is beneficial. Post-MI patients who reduced their daily cigarette intake by five experienced an 18% lower mortality risk compared to those who continued smoking at the same level.37
Prior studies have shown that a combination of pharmacotherapy and behavioral therapy can improve the success rate of smoking cessation by 70–100% when compared to minimal intervention such as brief unstructured advice to quit smoking.38 There are several different methods for behavioral therapy, including individual or group counseling, telephone or text message counseling, mobile applications, and self-help. Regardless of the treatment approach, patients should receive education on withdrawal symptoms, trigger identification, and coping strategies. Pharmacotherapy consists of nicotine replacement therapy, bupropion, or varenicline, all of which are effective, with the best data for varenicline.24,39 Although varenicline is beneficial for smoking cessation, there have been some concerns regarding the potential for adverse cardiovascular and neuropsychiatric effects, such as ischemic heart disease, cardiac arrhythmia, and depression.40 However, multiple trials have shown no increased risk for neuropsychiatric or cardiovascular events with varenicline when compared to nicotine patches or placebo.40–42 Unfortunately, relapse is common after smoking cessation. One trial showed that after 1 year post-MI, 60% of individuals receiving varenicline returned to smoking.43 Factors associated with a greater probability of smoking cessation include participation in CR, having a significant other, and intention to quit. Conversely, depression, lung disease, and unemployment are all associated with a lower likelihood of smoking cessation.44 Thus, providers should collaborate with their patients to identify the most effective treatment for smoking cessation, focus on factors that improve cessation, and work to promote sustained cessation.
Psychological Interventions
Experiencing a life-changing event such as an MI or needing PCI for SIHD can result in substantial psychological distress. Approximately 20% of acute MI survivors develop major depression, a rate three-times higher than in the general population.45 Importantly, post-MI depression has been associated with a nearly threefold increase in all-cause mortality, cardiovascular mortality, and cardiac events, and this association has remained unchanged over a 25-year timeframe.46,47 Although anxiety has been less studied, it is also an independent risk factor for cardiovascular mortality.48
Evidence-based treatment for mental health disorders consists of a combination of cognitive–behavioral therapy (CBT) or counseling and pharmacological interventions.5 The ENRICHD trial evaluated whether treatment of depression and low perceived social support with CBT plus a selective serotonin reuptake inhibitor (SSRI) reduced mortality and recurrent infarction in patients with MI.49 At 24 months, there was no improvement in event-free survival in those receiving CBT for depression versus usual care. However, a post hoc analysis of the ENRICHD trial found that depressed patients treated with an SSRI post-MI experienced a 42% lower risk of the primary endpoint, including death, nonfatal MI, and all-cause mortality, compared to non-SSRI users.49,50 Additionally, 24 weeks of treatment with escitalopram for patients with recent ACS and depression in the EsDEPACS study was superior to placebo in reducing MACE over a median follow-up period of 8.1 years.51,52 Therefore, antidepressants are an important component of care for patients with post-MI depression. Once patients start pharmacological therapy, frequent follow-up is essential to ensure adherence and to monitor side-effects that could lead to discontinuation.
CBT is also effective in reducing symptoms of depression and anxiety in patients with CAD, particularly through cognitive reconstruction for depression and relaxation techniques for anxiety.53 CBT characteristics shown to improve symptoms include individualizing therapy and emphasizing psychoeducation and cognitive-behavioral strategies.53
Importantly, patients with CAD should be screened for mental health disorders, both so that treatment can be initiated promptly to improve quality of life and mortality, and because depression and anxiety can influence lifestyle decisions and medication adherence.54
Nutrition and Alcohol
Diet is a key area of focus for patients in the post-MI or post-PCI period. Low consumption of fruits and vegetables is a modifiable risk factor for MI, with higher rates of consumption correlating to a reduced risk of mortality in individuals aged 35–70 years without cardiovascular disease.55,56 Dietary guidelines from several major cardiovascular societies emphasize a predominantly plant-based diet, limiting processed meats, refined carbohydrates, and sweetened beverages, while also reducing sodium intake and replacing saturated fats with mono- and polyunsaturated fats.57,58 These recommendations can be achieved through various dietary approaches such as the Mediterranean diet, Dietary Approaches to Stop Hypertension (DASH) diet, plant-based diet, ketogenic diet, or intermittent energy restriction.59
The Mediterranean diet primarily comprises leafy green vegetables, fruits, nuts, legumes, whole grains, extra virgin olive oil, fish, and seafood with limited poultry, eggs, and dairy. Intake of red meats and sweets is minimal.59 Within the Lyon Diet Heart Study, conducted in a post-MI population, individuals adhering to the Mediterranean diet experienced a 72% reduction in recurrent nonfatal MI and a 56% reduction in mortality over a follow-up period of 4 years compared to those receiving no specific dietary advice.60 The DASH diet is not only associated with reduced blood pressure but has also been shown to reduce noncalcified plaque and slow the progression of atherosclerosis when added to optimal medical therapy.61
A vegetarian diet is similar to the aforementioned diets but uses soy-based products as substitutes for meat, seafood, and poultry, while a plant-based diet removes all animal-based products, including dairy and eggs.59 Compared to non-vegetarian diets, vegetarian diets have been associated with a 30% lower risk of ischemic heart disease mortality.62 Satija et al. demonstrated that adherence to a ‘healthy’ plant-based diet was associated with a 25% reduction in CAD risk, whereas adherence to an ‘unhealthy’ plant-based diet was associated with an increased risk.63
The ketogenic diet consists of eating a low proportion of carbohydrates, 1 g of protein per kg of body weight per day, and the remaining calories in fat. This diet was initially proposed in the 1920s and widely used as a treatment for epilepsy in children.64 Since then, the ketogenic diet has been associated with numerous cardiovascular benefits, including weight loss, improved insulin sensitivity, reduced systemic inflammation, reduced blood pressure, and reduced risk for diabetes.65 While there are several versions of the ketogenic diet with various plant and animal sources of fat and protein, higher intake of animal sources has been associated with increased all-cause and cardiovascular mortality post-MI.59,65
In regard to hyperlipidemia, there is evidence that intake of saturated fatty acids elevates LDL-C levels, whereas intake of polyunsaturated fatty acids significantly lowers LDL-C compared to carbohydrates. Replacing 10% of saturated fatty acids with polyunsaturated fatty acids can lower LDL-C by 18 mg/dl.66 Thus, patients should be educated on the benefits of replacing foods containing saturated fats, such as red meat, dairy products, and lard, with foods rich in polyunsaturated fats, such as oily fish, dairy-free products, and olive oil.
The risk of developing hypertension increases with age and this modifiable cardiovascular risk factor can also be addressed through diet. Compared to the traditional Western diet, the DASH diet has been shown to lower systolic blood pressure (SBP) by 5.5 mmHg and diastolic blood pressure (DBP) by 3.0 mmHg, with further reductions seen in those with hypertension (SBP and DBP lowered by 11.4 and 5.5 mmHg, respectively).67 Furthermore, the DASH-Sodium trial demonstrated that reducing salt intake within the DASH diet led to decreases in SBP and DBP similar to treatment with a single anti-hypertensive medication.68
As for alcohol consumption, the recommended upper safety limit is 100 g of pure alcohol per week, which is equivalent to seven 12-ounce beers. Consumption beyond that is associated with lowered life expectancy.69 Although prior studies noted that moderate intake confers a cardiovascular benefit, these results have been challenged by a Mendelian randomized study suggesting that individuals who abstain from alcohol have the lowest risk for cardiovascular disease.58
Despite being a pillar for cardiovascular risk reduction, patient education on nutrition is infrequently provided by cardiovascular healthcare providers.70 There is evidence that patients can adhere to new dietary habits when guided appropriately, and the best way to accomplish this is for providers to become familiar with nutritional guidelines and the evidence supporting the impact of diet on cardiovascular health (Figure 1). To provide adequate nutritional advice, clinicians should screen for food insecurities, consider cultural habits and budget when making food recommendations, and use literacy-level appropriate educational materials.59 Because there are multiple ways to improve cardiovascular health through nutrition, patients do not need to adhere to a specific diet but can instead focus on the healthy habits that are most feasible for them.
Exercise and Healthy Weight
Increasing physical activity is a cornerstone of both primary and secondary prevention of CAD.71 Importantly, patients may be worried about increasing physical activity and decreasing sedentary behaviors in the post-MI period or after PCI for SIHD due to the concern of recurrent anginal symptoms. However, this is a crucial time for providers to encourage patients to increase physical activity to improve quality of life and reduce mortality risk. A study from 2018 investigating the effects of physical activity on 1-year survival in post-MI patients found a 71% and 59% mortality reduction in those who remained active or increased physical activity, respectively, when compared to those who remained inactive.71
Current guidelines recommend targeting 150–300 minutes of moderate-intensity physical activity or 75–150 minutes of vigorous-intensity physical activity per week, using a combination of aerobic and resistance exercises.57,58 Moderate-intensity physical activity includes walking at a brisk pace, painting, gardening, playing golf, playing doubles tennis, or doing water aerobics, whereas vigorous activity includes jogging, heavy gardening, swimming laps, or playing singles tennis. Physical activity should be tailored to the patient’s capabilities after MI or PCI.
In addition to increasing physical activity, losing weight to achieve and maintain a healthy weight is crucial for controlling other risk factors that contribute to cardiovascular disease. Even a 5% reduction in body weight from baseline improves blood pressure, cholesterol level, and glycemic control.57,58 This can be achieved through exercise and adherence to one of several hypocaloric diets as mentioned above. In addition to exercise and dietary changes, bariatric surgery and medical therapy are further options. Bariatric surgery not only reduces cardiovascular risk factors but has also been associated with a 45% reduction in all-cause mortality and a 41% reduction in cardiovascular mortality in obese patients when compared to BMI-matched controls who do not undergo surgery.72 In the SELECT Trial, the use of semaglutide versus placebo in non-diabetic patients with established cardiovascular disease and a BMI >27 kg/m2 was associated with a nearly 10% decrease in body weight and a 20% reduction in cardiovascular outcomes.35 These results highlight the importance of weight loss in modifying cardiovascular risk.
Cardiac Rehabilitation
CR is an integral part of secondary prevention in the post-MI period or after PCI for SIHD. CR comprises multidisciplinary and comprehensive programs offered to patients with cardiovascular disease to optimize cardiovascular health, foster and maintain healthy behaviors, and promote an active lifestyle. Beyond exercise training, CR programs emphasize health education, nutrition counseling, cardiovascular risk factor modification, and stress management.73,74 The programs usually consist of 36 sessions, conducted three times per week over a 12-week period.75 CR must be tailored to each patient for secondary prevention.
One of the major benefits of CR is reduced mortality risk. Several studies from the 1980s showed a significant reduction in cardiac mortality, total mortality, and fatal reinfarction among post-MI patients who participated in CR with exercise.76,77 A large cohort study of Medicare beneficiaries eligible for CR demonstrated a 21% reduction in 5-year mortality for CR participants compared to non-participants (Figure 2).78 Importantly, the benefits of CR in reducing mortality, MI, and all-cause hospitalization persist in patients receiving contemporary medical therapy.79 Notably, CR benefits appear dose-dependent, with greater session attendance leading to better long-term outcomes for MI and death.80
Other benefits of CR include improved exercise capacity, increased ischemic or anginal threshold, and decreased myocardial oxygen demand, all of which contribute to decreased symptoms and a better quality of life.74 CR can also relieve stress and improve mental health disorders such as depression. Milani et al. found a 63% decrease in depressive symptoms and a 73% reduction in mortality in depressed patients who completed CR compared to those who did not.81 The exercise training component of CR is linked to slower progression and reduced severity of coronary atherosclerosis, while also reducing inflammation, improving blood pressure, and increasing myocardial tolerance to prolonged ischemic stress.74
Furthermore, there is minimal risk associated with CR. Observational studies report 1.3 cardiac arrests per million patient-hours, 1 ventricular fibrillation per 111,996 patient-hours, and 1 MI per 294,118 patient-hours.82,83 Overall, patients should be reassured that CR is safe and the benefits substantially outweigh any potential risks.
Despite the numerous benefits of participating in CR, usage remains low. In 2005, only 10–20% of the 2 million eligible patients enrolled, and participation rates have seen little improvement since, with fewer than 30% of eligible patients participating in 2014.74,75 Reasons for low CR participation include low patient motivation, geographic location, and inadequate reimbursements; however, the biggest factor appears to be low referral rates, particularly among women, the elderly, and ethnic minorities.75 A meta-analysis examining sex bias in outpatient CR referral rates demonstrated that men were nearly 1.5 times more likely to receive a referral than women.84 Other characteristics associated with low likelihood of CR participation in post-MI patients included elderly age (>60 years), low educational attainment, low-income status, and reduced LVEF.85 Therefore, providers should focus their attention on encouraging the participation of individuals who may be less likely to participate in CR, promoting the benefits of CR, and improving referral rates for those who qualify.
Another important barrier is the geographic accessibility of facility-based CR (FBCR), which has led to the development of alternative models such as home-based CR (HBCR) and hybrid CR programs. A study comparing HBCR and FBCR in patients with recent ischemic heart disease events, such as ACS, PCI, or coronary artery bypass grafting surgery, found that those enrolled in HBCR had greater improvements in their 6-minute walk test distance, quality of life, and self-reported physical activity. They were also more likely to complete >85% of the program than patients enrolled in FBCR.86 In the HYCARET study, patients diagnosed with CAD were randomized to either hybrid CR or FBCR.87 The hybrid program consisted of two stages: an initial stage with 10 facility-based sessions, followed by a self-managed HBCR stage for the remainder of the program. At 1 year, the hybrid program was non-inferior to the FBCR program with respect to cardiovascular outcomes. Overall, these studies emphasize that both HBCR and hybrid CR are excellent alternatives to FBCR and may improve overall participation.
Conclusion
In the vulnerable period post-MI or after PCI, it is crucial for clinicians to work closely with patients to optimize secondary prevention. This involves starting appropriate pharmacotherapy, emphasizing lifestyle changes, and promoting participation in CR to improve patients’ cardiovascular health. A key lifestyle change is to adopt a healthy, balanced diet focused on whole grains, fruits, and vegetables to support weight management and reduce cholesterol and blood pressure, thereby lowering cardiovascular risk. Furthermore, increased physical activity, appropriate psychological interventions, and smoking cessation are critical elements of secondary prevention. CR is an effective, comprehensive intervention that incorporates most secondary prevention strategies tailored to this population, with the aim of improving quality of life and reducing mortality.