Dr. Eduardo Alegria-Ezquerra
This article is written by the author for the newsletter of the Council for Cardiology Practice. It reflects the opinion of the author. Elevated blood glucose levels define diabetes mellitus (DM) and pre-diabetic states. Both DM and other disorders of glucose metabolism (pre-diabetes) have a huge and rising prevalence in Europe and are risk factors for cardiovascular (CV) disease, silently developing many years before clinical events appear, in parallel to the progression from pre-diabetic status to type 2 DM.
Both general and DM-specific scores for assessing CV risk are of limited value in patients with DM or pre-diabetes. Accordingly, ESC guidelines have simplified CV risk stratification into two categories: very high risk if CV disease is already present; and high risk in the remaining patients with type 2 DM or pre-diabetes. Therefore, CV disease should be investigated in patients with DM or metabolic syndrome.
On the other hand, disorders of glucose metabolism should be investigated in all patients with a CV event. Glycated haemoglobin (A1c), fasting plasma glucose, or both are recommended as screening procedures. Oral glucose tolerance test is recommended for its high predictive value for CV events in all cases in which other parameters are normal.
Lifestyle adjustment is the first and most powerful therapy for preventing CV disease in patients with type 2 DM or pre-diabetic states. Main components are: a) to stop and/or to avoid smoking; b) to maintain a normal weight; c) to consume a healthy diet; and d) to increase physical activity.
Tight glucose control reduces microvascular complications in type 1 and type 2 DM. CV events are also reduced with strict glucose control in type 1 DM, but not so consistently in recently diagnosed type 2 DM, and almost nothing in long-standing type 2 DM (elderly patients). Therefore, ESC guidelines recommend the standard glycaemic target (HbA1c less than 7%) in most of the cases and a tighter target (6.5 to 6.9%) for selected patients, i.e, younger, with DM of short duration, and without co-morbidities.
Blood pressure control has also been simplified, according to recent European guidelines. Diastolic pressure target should be <85 mm Hg for all patients with DM. Systolic target is set at <140 mm Hg for all patients, except in those with nephropathy and proteinuria, in whom systolic target should be lowered to <130 mm Hg.
Recommended lipid-lowering strategies are in accordance with the 2011 ESC guidelines on dyslipidaemias. Main treatment target should be LDL-cholesterol and statins are the principal drugs to achieve recommended values: less than 1.8 mmol/L (70 mg/dL) for patients with DM and very high risk, and less than 2.5 mmol/L (100 mg/dL) for those at high risk. Non-HDL-cholesterol is considered a secondary objective.
Aspirin is recommended in patients with DM and high risk and on an individual basis. For secondary prevention, aspirin (or clopidogrel if intolerance) is indicated indefinitely.
Optimal medical treatment is the preferred modality for patients with DM and stable coronary disease. Classical indications for beta-blockers, angiotensin converting enzyme inhibitors or angiotensin receptor blockers, statins, and antiplatelet drugs are summarized in the guidelines.
Coronary artery bypass surgery is preferred over percutaneous coronary intervention in complex multivessel disease, aiming for complete revascularization with arterial bypass grafts. For percutaneous revascularization, drug-eluting stents rather than bare-metal stents are preferred to reduce the risk of target vessel re-interventions.
Drug treatment for heart failure in patients with DM includes the classical triad (angiotensin converting enzyme inhibitor, betablocker, and diuretic if necessary). An aldosterone antagonist should be added in patients with ejection fraction <35% and persistent symptoms. Ivabradine may be added for symptomatic patients with low ejection fraction, sinus rhythm, and high resting heart rate.
Atrial fibrillation is highly prevalent in diabetic patients. Therefore, it is recommended to investigate if silent paroxysmal atrial fibrillation is present. Vitamin K antagonists or novel oral anticoagulants are considered equal alternatives to achieve embolic prevention.
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