Endocrinology Metabolism

Diabetes and Cardiovascular Disease

Are You Sure the Patient Has a Cardiovascular Complication of Diabetes?

Scope of the Problem

Cardiovascular disease is the leading cause of morbidity and mortality in patients with diabetes mellitus. When examining the impact of cardiovascular disease on diabetic patients and the importance of appropriate screening and treatment, it is vital to bear in mind the following considerations:

  • According to the National Cholesterol Education Program, diabetes is currently considered a coronary heart disease (CHD) equivalent.

  • Diabetes increases the risk of CHD or ischemic stroke by 2-fold.

  • Cardiac events often occur unheralded in patients with diabetes.

  • Patients with type 2 diabetes have a high rate of asymptomatic coronary artery disease (CAD) as determined by the presence of coronary artery calcification and coronary stenosis on coronary angiography and by inducible silent ischemia on stress testing.

  • Patients with diabetes have an increased incidence of silent MI, which is thought to be caused at least in part by autonomic denervation of the heart, and this phenomenon also contributes to a delay in the onset of ischemic changes during stress testing or the perception of angina.

  • When presenting with symptomatic CAD or MI, patients with diabetes tend to have more severe and atypical presentations compared to patients without diabetes.

  • Compared to non-diabetics, patients with diabetes have a higher incidence of multi-vessel CAD among both symptomatic and asymptomatic patients.

  • Diabetes is associated with increased risk of myocardial infarction (MI), and patients with type 2 diabetes without a prior infarction are at the same risk for MI and coronary mortality as non-diabetics with a prior MI.

  • Diabetic patients who sustain an MI have a higher risk of developing significant complications after the initial event, including arrhythmias, congestive heart failure, cardiogenic shock and recurrent MI.

  • Diabetic patients have been shown to have worse mortality after sustaining an MI compared to non-diabetics.

  • As many as 50% of patients with type 2 diabetes will develop heart failure.

For these reasons, it is critical that patients with diabetes undergo comprehensive CHD risk assessment and aggressive treatment to reduce the impact of cardiovascular disease.

Pathophysiology

There are a number of potential mechanisms by which diabetes increases the risk of cardiovascular disease, apart from the effects on blood pressure and lipid abnormalities:

  • Diabetic patients have increased endothelial dysfunction, with the degree of dysfunction being related to the duration of diabetes.

  • Diabetes confers an overall prothrombotic state, as evidenced by platelet hyperreactivity, elevated plasma fibrinogen levels, decreased fibrinolytic activity via decreased tissue-type plasminogen activator (tPA) activity due to increased binding with plasminogen activator inhibitor (PAI-1), as well as other mechanisms of impaired fibrinolysis

  • Type 2 diabetes may confer changes in plaque composition that may contribute to increased risk of plaque rupture and thrombosis, including increased macrophage infiltration and increased lipid-rich atheroma.

  • Diabetes is associated with HTN and IHD which increase the risk of heart failure with reduced ejection fraction (HFrEF). Diabetes is also associated with LV remodeling and fibrosis resulting in myocardial (and vascular) stiffness, thereby increasing the propensity of diastolic dysfunction or heart failure with preserved ejection fraction (HFpEF).

History and physical examination

Patients with diabetes should undergo a comprehensive history and physical examination and evaluation of risk factors for cardiovascular disease.

In case of angina symptoms, further historical information should be obtained regarding the onset, location, severity, duration and frequency of chest pain, radiation, association with activity and any aggravating or alleviating factors.

Atypical symptoms suggestive of underlying cardiovascular disease, such as dyspnea on exertion, worsening fatigue, and nausea and vomiting are common in patients with diabetes, especially women.

Patients should be questioned about their level of physical activity and endurance.

History should include evaluation of the presence of risk factors for CVD, and these risk factors should be assessed annually. Risk factors include:

Smoking: current and past smoking habits, smoking duration and intensity, possible exposure to passive smoke

Obesity: evaluation of history of body weight and associated weight loss and weight gain, eating patterns, social and occupational factors affecting body weight.

Blood pressure: evaluation of patient self-assessment of blood pressures, assessment of factors that may contribute to hypertension (i.e. alcohol use, sodium intake, body weight, sodium intake), evaluation of prior and current antihypertensive therapy

Dyslipidemia: dietary and exercise habits, prior patient efforts to effect lifestyle modification, use of medications that may affect lipid profile

Family history of early CVD: assessment of the cardiovascular disease in male first degree relative of age less than 55 years old or female first degree relative less than 65 years old.

Physical examination should include height, weight, BMI, blood pressure measurement, comprehensive cardiovascular examination, and assessment for physical exam findings that may be suggestive of dyslipidemia (i.e. xanthomas).

Asymptomatic patients

Despite the fact that patients with diabetes have an increased rate of asymptomatic CAD and silent ischemia compared with the general population, routine screening for CAD, via exercise or pharmacologic stress testing, or with newer modalities such as coronary artery calcium score (CACS) or coronary CT angiography (CCTA), is NOT recommended in asymptomatic patients according to the 2017 ADA Standards of Care (Level A recommendation).

This recommendation is principally based on the results of a randomized trial evaluating the role of Myocardial Perfusion Imaging (MPI) in Detection of Ischemia in Asymptomatic Diabetics (DIAD). The principal findings of this trial were:

  • Silent ischemia was detected in only 22% of patients; most patients had mild perfusion abnormalities that were not necessarily suitable for revascularization; and perfusion defects could not be easily identified through routine risk factor analysis.

  • The prevalence of myocardial ischemia did not increase over time, with many perfusion defects resolving with contemporary optimal medical therapy.

  • Although screening with MPI identified a higher-risk cohort of patients, screening did not favorably alter outcomes.

  • Based on these results, and since aggressive medical therapy is already warranted in diabetes (a CHD equivalent), the use of screening to identify patients with evidence of CAD is not likely to alter the medical management of asymptomatic diabetic patients, and effectively unlikely to influence their overall prognosis.

Similarly, screening with bicycle exercise (DYNAMIT) or CCTA (FACTOR-64) failed to favorably alter outcomes in asymptomatic patients with type 2 diabetes.

The 2010 ACCF/AHA guidelines for CVD risk assessment in asymptomatic adults with diabetes recommend:

  • CACS assessment in patients over the age of 40 years (Class IIa, level of evidence B).

  • Resting EKG (Class IIa, level of evidence C).

  • MPI in patients with CACS above 400 (Class IIb, level of evidence C).

  • CCTA or MRI should not be used (Class III, level of evidence C).

The recommendations for CACS assessment have been downgraded to Class IIb in the 2013 ACC/AHA Cholesterol Treatment Guidelines.

Symptomatic patients

Patients should undergo further testing for cardiac disease if they have concerning typical or atypical cardiac symptoms as assessed by history, or those patients who have an abnormal resting electrocardiogram.

Exercise ECG stress testing should be reserved for patients who can exercise and who have a normal resting electrocardiogram, but given the widespread availability and greater specificity of ECG stress testing when combined with an imaging modality, exercise ECG testing should mainly be utilized to assess exercise response and functional ability as indicators of overall prognosis.

For the purposes of CAD diagnosis, SPECT radionuclide myocardial perfusion imaging and stress echocardiography have similar sensitivities (about 90%) and specificities (about 50%) for detecting anatomically significant coronary artery stenoses (defined as greater than 70% stenosis in a vessel found on coronary angiography), and either modality can be used depending on absolute and relative patient contraindications and local operator expertise.

Exercise should be the preferred modality of stress in all forms of testing, as the patient's response to exercise has prognostic value. Poor prognostic indicators include inability to exercise beyond 5 METS, fall in systolic blood pressure with exercise, development of exercise-induced angina, and chronotropic incompetence (inability to increase heart rate appropriately in response to exercise). If the patient cannot exercise, pharmacologic stress should be used.

Key Laboratory and Imaging Tests

Laboratory evaluation

The American Diabetes Association (ADA) recommends the following laboratory assessment:

  • Fasting lipid panel, including HDL, LDL, triglycerides and total cholesterol levels should be assessed at the time of diagnosis, at the initial medical evaluation, and at least every 5 years thereafter. A lipid panel should also be obtained immediately before initiating statin therapy. Once a patient is taking a statin, testing for LDL cholesterol may be considered on an individual basis (e.g., to monitor for adherence and efficacy).

  • Hemoglobin A1c.

  • Serum creatinine and urine albumin-to-creatinine ratio if urine dipstick is negative for proteinuria.

  • Liver function tests.

  • Thyroid function tests.

Management and Treatment of the Disease

Treatment of Risk Factors for Cardiovascular Disease in the Diabetic Patient

Common conditions that coexist with diabetes, such as hypertension and dyslipidemia, largely contribute to increased risk of cardiovascular disease in this patient population, and treatment should be pursued with a global approach, addressing these comorbidities aggressively in diabetic patients.

Hypertension

Hypertension is a common comorbidity of diabetes and contributes to increased risk of both microvascular and macrovascular disease. Blood pressure (BP) control should be pursued in diabetic patients in concert with the recommendations of the ADA:

  • The blood pressure (BP) goal should be less than 140/90 mm Hg (Level A recommendation).

  • Lower systolic and diastolic blood pressure targets, such as 130/80 mmHg, may be appropriate for individuals at high risk of cardiovascular disease, if they can be achieved without undue treatment burden (Level C recommendation).

  • Diabetic patients with a BP of greater than 140/90 mm Hg should be initiated on pharmacologic therapy in addition to lifestyle modification, preferably with a regimen demonstrated to reduce cardiovascular events that includes an ACE inhibitor, an angiotensin II receptor blocker (ARB), thiazide-like diuretics or dihydropyridine calcium channel blocker and should include multiple pharmacologic agents if needed to obtain target blood pressure (Level A recommendation; Trial evidence: ADVANCE, ACCOMPLISH, HOT, ACCORD).

  • For patients with blood pressure >120/80 mmHg, lifestyle intervention consists of weight loss if overweight or obese; a Dietary Approaches to Stop Hypertension (DASH)– style dietary pattern including reducing sodium and increasing potassium intake; moderation of alcohol intake; and increased physical activity (Level B recommendation).

Dyslipidemia

The prevalence of lipid abnormalities is increased in diabetic patients, contributing to the increased incidence of cardiovascular disease seen in these patients.

Lifestyle modification is an essential part of lipid management in diabetic patients, and should focus on reduction in the intake of saturated fat, trans fat, and cholesterol, increase of dietary ?-3 fatty acids, viscous fiber, and plant stanols/sterols intake, as well as weight loss and increased physical activity (Level A recommendation).

Statin therapy

All diabetic patients with overt atherosclerotic cardiovascular disease (ASCVD) or those above the age of 40 plus additional risk factors for ASCVD should be treated with a statin, regardless of baseline lipid levels. The intensity of initial statin therapy should be based on underlying risk as determined by age, ASCVD or risk factors for ASCVD rather on LDL levels.

  • For patients of all ages with diabetes and atherosclerotic cardiovascular disease, high-intensity statin therapy should be added to lifestyle therapy (Level A recommendation).

  • For patients with diabetes aged >40 years with additional atherosclerotic cardiovascular disease risk factors, consider using moderate intensity or high-intensity statin and lifestyle therapy (Level C recommendation).

  • For patients with diabetes aged 40–75 years without additional atherosclerotic cardiovascular disease risk factors, consider using moderate-intensity statin and lifestyle therapy (Level A recommendation).

  • For patients with diabetes aged 40–75 years with additional atherosclerotic cardiovascular disease risk factors, consider using high-intensity statin and lifestyle therapy (Level B recommendation).

  • For patients with diabetes aged >75 years without additional atherosclerotic cardiovascular disease risk factors, consider using moderate-intensity statin therapy and lifestyle therapy (Level B recommendation).

  • For patients with diabetes aged >75 years with additional atherosclerotic cardiovascular disease risk factors, consider using moderate intensity or high-intensity statin therapy and lifestyle therapy (Level B recommendation).

Intensity of statin therapy should be adjusted based on individual patient response to medication (e.g., side effects, tolerability, LDL cholesterol levels) (Level E recommendation).

At the present time, there is no convincing data that treatment of low HDL and elevated triglycerides results in incremental CVD risk reduction when the LDL is at target on statin therapy. Furthermore, combination therapy is associated with an increased risk of transaminitis, myositis and rhabdomyolysis. Therefore, treatment of low HDL or elevated triglycerides is not recommended at this time.

  • Combination therapy (statin/fibrate) has not been shown to improve atherosclerotic cardiovascular disease outcomes and is generally not recommended (Level A recommendation).

  • However, therapy with statin and fenofibrate may be considered for men with both triglyceride level >204 mg/dL (2.3 mmol/L) and HDL cholesterol level <34 mg/dL (0.9 mmol/L) (Level B recommendation).

  • Combination therapy (statin/niacin) has not been shown to provide additional cardiovascular benefit above statin therapy alone and may increase the risk of stroke and is not generally recommended (Level A recommendation).

  • The addition of ezetimibe to moderate-intensity statin therapy has been shown to provide additional cardiovascular benefit compared with moderate-intensity statin therapy alone for patients with recent acute coronary syndrome and LDL cholesterol >50 mg/dL (1.3 mmol/L) and should be considered for these patients (Level A recommendation) and also in patients with diabetes and history of ASCVD who cannot tolerate high-intensity statin therapy (Level E recommendation).

Patients with severe hypertriglyceridemia (fasting triglyceride levels >500 mg/dL or 5.7 mmol/L) may require medical therapy with fibrates, niacin, or fish oil to reduce the risk of pancreatitis (Level C recommendation).

Glycemic control

The ADA proposes optimal targets for glycemic control but each target must be individualized to the needs of each patient and their disease factors.

Most patients with diabetes should be encouraged to target a hemoglobin A1c goal of less than 7% (Level A recommendation).

Recent randomized control trials of intensive (targeting HbA1c of less than 6.0-6.5%) vs. standard glycemic control (targeting HbA1c of less than 7%), such as the ACCORD, ADVANCE, and VADT trials, did not demonstrate a significant reduction in cardiovascular disease outcomes with intensive glycemic control. A modest, but significant, benefit in reducing cardiovascular disease outcomes, primarily nonfatal MI, was observed in a pooled analysis of these three trials.

Nevertheless, intensive glycemic control needs to be balanced against the increased risk of hypoglycemic events, which were increased in the intensive glycemic arms of all of these trials. It is possible that in some patients, the risks of intensive glycemic control compared to standard glycemic control may outweigh the benefits, such as those with very long duration of diabetes, known history of severe hypoglycemia, advanced atherosclerosis, and advanced age/frailty. In such individuals, less stringent goal (HbA1c <8%) may be appropriate (Level B recommendation). Conversely, it may be reasonable to pursue more intensive glycemic control (HbA1c <6.5%) to reduce cardiovascular disease risk in younger patients with a long life expectancy who do not have evidence of advanced atherosclerosis and who are diligent about their medical therapy and are able to adequately monitor for adverse effects (Level C recommendation).

Smoking cessation is an essential part of cardiovascular disease risk reduction in diabetic patients and should be an integral component in comprehensive diabetes management.

Acute myocardial infarction (AMI) in diabetic patients

The presence or absence of diabetes should not influence the decision process with respect to coronary reperfusion in patients with AMI. Specifically, in diabetic patients with ST segment elevation myocardial infarction (STEMI), an immediate revascularization strategy should be pursued, preferably with percutaneous coronary intervention (PCI), or thrombolytic therapy if PCI is unavailable in a timely manner. However, diabetic patients tend to have better outcomes with PCI compared to fibrinolysis.

Antiplatelet therapy

Antiplatelet therapy in the setting of AMI

All patients who have sustained a MI should be administered aspirin indefinitely, regardless of the presence or absence of diabetes.

In the setting of PCI for NSTEMI or STEMI, P2Y12 inhibitor such as clopidogrel, ticagrelor or prasugrel should be administered in addition to aspirin, with the duration of P2Y12 inhibitor administration depending on the type of stent placed.

In patients who sustain an NSTEMI and are treated with medical therapy, P2Y12 inhibitor such as clopidogrel or ticagrelor, but not prasugrel, should be administered in addition to aspirin for at least 1 year.

In patients with diabetes and prior MI (1–3 years before), adding ticagrelor to aspirin significantly reduces the risk of recurrent ischemic events including cardiovascular and coronary heart disease death.

Glycoprotein IIb/IIIa inhibitors have been used as adjunctive antiplatelet therapy in the setting of STEMI and NSTEMI in patients undergoing PCI. While there are no clear data on mortality benefit in diabetic patients in the setting of STEMI, a mortality benefit in diabetic patients was reported in a meta-analysis of six randomized trials in the setting of NSTEMI (30-day mortality of 6.2% vs. 4.6%, OR 0.74).

Aspirin for primary prevention of CVD

Aspirin at a dose of 75-162 mg/day for primary prevention of cardiovascular disease may be considered in diabetic patients who are at increased risk of developing CVD (10-year CVD risk greater than 10%), i.e. men or women above 50 years of age who have one or more additional risk factors for CVD (hypertension, smoking, dyslipidemia, family history of early CVD) and who do not have an increased risk of bleeding (Level C recommendation). However, recent randomized controlled clinical trials of aspirin for primary prevention of CVD in diabetic patients have failed to demonstrate a significant reduction in risk of cardiovascular disease outcomes. (Trial evidence: JPAD, POPADAD)

Diabetic patients with a low risk of cardiovascular disease (10 year CVD risk less than 5%), i.e. men or women under 50 years of age with no other risk factors for cardiovascular disease should not be given aspirin for primary prevention of cardiovascular disease, as the low benefit is likely outweighed by the increased risk of bleeding (Level C recommendation).

Aspirin should be utilized for secondary prevention in patients with known cardiovascular disease (Level A recommendation).

In patients with documented allergy to aspirin and a strong indication for antiplatelet therapy, clopidogrel should be used as a substitute, at a dose of 75 mg (Level B recommendation).

Ace inhibitor therapy

ACE inhibitor therapy is recommended to reduce the risk of future cardiovascular events in diabetic patients with cardiovascular disease.

When used after an acute coronary syndrome (ACS), ACE inhibitors reduce infarct size, limit ventricular remodeling, and reduce mortality; they also may provide substantial benefit in diabetic patients even compared to non-diabetic patients who sustain an ACS.

ACE inhibitors should be administered long-term in diabetic patients after an ACS, provided that there are no contraindications to continued use (i.e. hyperkalemia, worsening renal insufficiency).

Beta blockers

Beta blockers are an important medical therapy in the treatment of cardiovascular disease in diabetic patients, and particularly in the setting of ACS, as they have been shown to reduce the incidence of recurrent ischemia and repeat infarction, reduce infarct size and improve mortality.

While there has been concern that beta blockers may mask hypoglycemic symptoms, which has historically resulted in underuse of beta blockers in diabetics, this concern has not been borne out in clinical trials. In contrast, diabetic patients may derive even greater benefit from beta blockers.

Beta blockers should be used for the treatment of patients who have sustained a MI provided there are no contraindications present (i.e. history of severe bronchospasm, bradycardia); they should be continued for at least 2 years after the event, and may be continued indefinitely in patients if well tolerated.

Aldosterone antagonists

Aldosterone antagonists should be administered to all diabetic patients who are being treated with an ACE inhibitor, have an LV ejection fraction less than 40%, have a serum creatinine less than 2.5 mg/dL in men and less than 2.0 mg/dL in women, and have a serum potassium less than 5.0 mEq/L

Serum potassium levels should be monitored closely during treatment, particularly with concomitant use of ACE inhibitor therapy, due to increased risk of hyperkalemia.

Statins

Statins should be administered to all diabetic patients as per the guidelines described.

In the setting of ACS, acute administration of statins in statin-naïve patients previously may provide additional benefit with respect to cardiovascular outcomes, and should be administered to all patients in the absence of contraindications.

Antihyperglycemic therapies

Recently published cardiovascular outcome trials have provided evidence for the first time that supports the use of antihyperglycemic agents in mitigating cardiovascular risk in patients with type 2 diabetes with cardiovascular disease or at high risk for cardiovascular disease.

  • EMPA-REG OUTCOME showed that over a median follow-up of 3.1 years, treatment with empagliflozin, a selective inhibitor of sodium glucose cotransporter 2 (SGLT2), reduced the composite outcome of cardiovascular death, nonfatal MI, or nonfatal stroke by 14% and cardiovascular death by 38%. The FDA recently added a new indication for empagliflozin, to reduce the risk of cardiovascular death in adults with type 2 diabetes and cardiovascular disease. Whether other SGLT2 inhibitors will have the same effect in high-risk patients and whether empagliflozin or other SGLT2 inhibitors will have a similar effect in lower-risk patients with diabetes remains unknown.

  • LEADER showed that over a median follow-up of 3.8 years, treatment with liraglutide, a glucagon-like peptide 1 (GLP-1) receptor agonist, reduced the composite outcome of cardiovascular death, nonfatal MI, or nonfatal stroke by 13% and cardiovascular death by 22%. Whether other GLP-1 receptor agonists will have the same effect in high-risk patients or if this drug class will have similar effects in lower-risk patients with diabetes remains unknown.

  • Based on the results of these two large clinical trials, ADA recommends adding empagliflozin or liraglutide in patients with established cardiovascular disease to reduce the risk of mortality.

Diabetic medications that are contraindicated in patients with cardiovascular disease

Thiazolidinediones should not be used in patients with symptomatic congestive heart failure.

Metformin should not be administered in unstable patients or hospitalized with congestive heart failure.

DPP4 inhibitors Saxagliptin and alogliptn (but not sitagliptni) may increase the risk of heart failure, particularly in patients who already have heart or kidney disease. Consider discontinuing these drugs in patients who develop heart failure.

Coronary Revascularization in Diabetic Patients

The indications for revascularization in patients with diabetes and stable angina or ACS are similar to those in patients without diabetes.

Trials of optimal medical therapy (OMT) vs. revascularization (PCI or CABG) in diabetic patients with stable ischemic heart disease (Trial evidence: COURAGE, BARI-2D) have failed to yield a significant difference in clinical outcomes.

Generally, OMT should be the preferred initial treatment strategy unless the patient has high-risk features associated with a survival benefit with CABG, i.e., left main disease, multivessel CAD with impaired LV systolic function, or a large area (greater than 10-20%) of ischemic myocardium at jeopardy. If symptoms are not alleviated with maximally titrated OMT, revascularization should be recommended.

Diabetic patients who undergo PCI or CABG often have worse outcomes compared with non-diabetics. While procedural success rates in elective PCI are generally similar, diabetic patients have higher rates of restenosis and lower rates of event-free survival.

Risk factors for restenosis in diabetic patients include smaller vessel size, greater length of segment that is stented, and lower BMI.

There is data to suggest that the rate of restenosis is reduced in patients who have optimal glycemic control prior to the procedure (HbA1c less than 7%), which highlights the importance of good glycemic control in improving cardiovascular disease outcomes in diabetic patients.

Diabetic patients undergoing CABG for revascularization also tend to have increased mortality as well as an increased incidence of nonfatal cardiac and non-cardiac outcomes (i.e. renal failure, wound infection) compared to non-diabetics, due to a number of factors which include tendency toward having lower ejection fraction and multivessel disease compared to non-diabetics, and higher prevalence of additional comorbidities, such as peripheral vascular disease and renal failure.

Similar to PCI, studies have shown that good glycemic control in the perioperative period during surgical revascularization is associated with lower rates of post-operative comorbidities and may also reduce the development of future recurrent ischemia and reduce long-term post-operative mortality.

Intensive post-procedural medical therapy, including good glycemic control, which should be undertaken with the assistance of an endocrinologist if needed, is a cornerstone of both percutaneous and surgical revascularization in diabetic patients.

Drug-eluting stents (DES) vs. bare-metal stents (BMS) for PCI in diabetic patients

DES should be used preferentially in diabetic patients if indicated by the vessel characteristics (smaller and longer diseased segments), due to significantly decreased incidence of in-stent restenosis, although this is balanced with a small increased incidence of late stent thrombosis.

Patients who have socioeconomic barriers to P2Y12 inhibitor access or who have contraindications to long-term dual anti-platelet therapy should be treated with BMS.

Patients who have undergone PCI with DES who are tolerating dual antiplatelet therapy without significant adverse effects and have a high stent burden or a prior history of restenosis can be considered for indefinite continuation of dual antiplatelet therapy.

When comparing 1st generation DES (sirolimus and paclitaxel) vs. 2nd generation DES (everolimus and zotarolimus) in diabetic patients, there appears to be equal long-term efficacy with respect to rates of target vessel revascularization and safety with respect to stent thrombosis, with everolimus-eluting stent showing the lowest rates of stent thrombosis.

PCI vs. CABG for revascularization in diabetic patients

Historically, CABG has been the preferred modality for revascularization in diabetic patients due to higher rates of mortality and need for repeat target vessel revascularization in patients undergoing PCI (Trial evidence: BARI). However, with the advent of DES and increasing widespread use of multivessel stenting, recent data has emerged indicating that major adverse cardiac events (CV death, nonfatal MI or nonfatal stroke) are comparable among patients undergoing PCI or CABG (Trial evidence: SYNTAX).

While the risk of procedural stroke is increased with CABG, PCI is associated with increased rates of repeat revascularization. One recent trial (Trial evidence: CARDIA) failed to establish noninferiority of PCI compared with CABG in diabetic population in terms of primary composite outcome of death, stroke or MI. A large randomized trial (FREEDOM) comparing PCI with CABG in diabetic patients with multivessel CAD confirmed the superiority of CABG over PCI in significantly reducing rates of death and myocardial infarction, but with a higher rate of stroke. According to current ACC/AHA guidelines, the following is recommended with respect to revascularization in diabetic patients:

  • PCI is preferred in patients who have single vessel or two vessel CAD that does not include proximal left anterior descending artery stenosis and have inducible ischemia. CABG is preferred in patients who have three vessel disease or two vessel disease that involves significant proximal left anterior descending artery disease. PCI can be considered if the patient is a poor surgical candidate, has focal, relatively non-complex lesions that would be amenable to PCI, and if the PCI can be performed by an experienced operator.

  • Despite increasing use of DES for the treatment of left main coronary artery disease, CABG is still the preferred method of revascularization in this setting, although PCI can be considered if the patient is a poor surgical candidate, has a lesion with characteristics that would be amenable to PCI (low to intermediate SYNTAX score, i.e., SYNTAX score <33), and if the PCI can be performed by an operator experienced in the percutaneous treatment of left main disease.

  • To address the important issue of deciding between PCI and CABG in patients with diabetes mellitus and complex multivessel CAD, a Heart Team approach would be beneficial. The Heart Team is a multidisciplinary team composed of an interventional cardiologist and a cardiac surgeon who jointly 1) review the patient's medical condition and coronary anatomy, 2) determine that PCI and/or CABG are technically feasible and reasonable, and, 3) discusses revascularization options with the patient before a treatment strategy is selected.

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