IN FOCUS
Cardiodiabetology : Endocrinologists and Cardiologists Working Together to Improve Clinical Outcomes
With atherosclerotic cardiovascular disease ( ASCVD ) and its complications ( i . e . heart attacks , strokes , chronic kidney disease and heart failure ) among the principal causes of death in persons with type 2 diabetes mellitus ( T2DM ), the field of cardiodiabetology prompts a close collaboration between the practicing endocrinologist and cardiologist notes Nathan D . Wong , PhD , of the University of California , Irvine . In addition , it is important to have other diabetes treatment experts , including nephrologists , exercise physiologists , nutrition experts ( i . e . registered dieticians ), podiatrists , and not uncommonly , cardio-thoracic and other vascular surgeons , along with the referring primary care physicians , to be part of the team aimed to improve patient outcomes , longevity and quality of life notes Paul D . Rosenblit , MD , PhD , of the University of California , Irvine .
Several lines of evidence support the necessity of a multidisciplinary approach , especially in the secondary prevention setting when the cardiologist is most often initially involved in patient care . First , we know that few patients with T2DM , even in the US , despite its sophisticated healthcare systems , attain guideline directed goals for the conventional cardiovascular risk factors including lipids , blood pressure , blood glucose , and weight , and when inadequately controlled , lead to significant residual risk for cardiovascular complications , notes Norman Lepor , MD , of Cedars-Sinai Medical Center .
Wong and colleagues previously published data from the US National Health and Nutrition Examination Survey noting that while approximately 50 % of patients with T2DM may reach targets for glycated hemoglobin ( HbA1c ), blood pressure ( BP ) or low density lipoprotein ( LDL ) -cholesterol , the likelihood that all three risk factors together are at target is only 25 %. In addition , only 10 % had a normal body mass index ( BMI ); i . e . below 25 kg / m 2 , and only 4 % attained all four targeted goals . 1 The STENO-2 trial showed that controlling multiple modifiable CV risk factor measures can reduce the risk of future cardiovascular disease ( CVD ) outcomes by nearly 60 %. 2 Wong and colleagues recently also demonstrated from a pooling of diabetes subjects from 3 major prospective epidemiologic studies ( MESA , ARIC , and Jackson ) that those who met all three guideline-based goals for targeted HbA1c , LDL-C , and BP had 60 % lower CVD event risks compared to those who met none of the goals . 3
Several lines of evidence support the necessity of a multidisciplinary approach , especially in the secondary prevention setting when the cardiologist is most often initially involved in patient care .
Barriers to achieving targeted goals include a perceived lack of unifying recommendations among stakeholder organizations , regarding the actual goals and the methods for their achievement , and even the perceived necessity of achieving those goals . Other barriers may include the increasingly available numbers and classes / types of pharmaceutical agents to control lipids , blood pressure , blood glucose and weight , along with a complexity of choice decisions ; these decisions become particularly difficult in the settings of secondary prevention , where co-morbidities ( i . e . CKD , heart failure , liver abnormalities ) often limit the choice ( s ) or dose ( s ) of many agents within multiple classes that may be required for control of modifiable risks .
The association of hyperglycemia with microvascular complications [ i . e . retinopathy , neuropathy , nephropathy ( CKD )] and with ASCVD events has been demonstrated in many epidemiologic studies . Randomized clinical trials ( RCTs ) have clearly demonstrated that reducing hyperglycemia reduces onset and progression of microvascular disease . But , while the multifactorial role of hyperglycemia in unfavorably modifying the atherosclerotic environment has been recognized for decades , RCTs , historically , have failed to demonstrate that glycemic control reduces ASCVD events significantly . Post-hoc analyses , however , do support an approximate 16 % reduction of ASCVD events for each 1 % reduction of A1C . Furthermore , even with the perhaps ethically-driven inadequate between-group A1c differences from several trials , a legacy or memory effect , has been noted like that observed long after trials have been completed using lipid lowering agents ( i . e . niacin , fibrate , statins ); suggesting early treatment can have long-term positive effects . Special cardio-protective properties , beyond glucose control , have been suggested for metformin , with uncertain mechanisms of action , as observed in sub-group analyses of the UKPDS . While metformin is the first line agent in global diabetes recommendations , proper use becomes challenging and complex , with the potential for progressive CKD , heart failure , or chronic atrial fibrillation . The thiazolidinedione ( TZD ) pioglitazone , among high risk secondary prevention patients , in PROACTIVE , CHICAGO and PERISCOPE , reduced nonfatal myocardial infarction , stroke , and all-cause death , reduced carotid intimal media thickness , and coronary artery plaque volume . Another unique TZD property is beta cell preservation that has been demonstrated in multiple studies , including those dedicated to diabetes prevention . The TZD benefits are attributed to a considerable reduction in insulin resistance . Pioglitazone was added to the 2008 European Stroke Organization recommended agents for secondary stroke prevention in patients with type 2 diabetes ( Class III , Level B ). While TZDs also affect visceral fat reduction , this benefit may be offset by the known potential overall side effect of weight gain , from both water retention ( edema ) and increased subcutaneous fat weight gain . In secondary prevention , and even primary prevention , a challenge is the potential risk for heart failure , associated TZD-induced fluid retention , in the susceptible patient with pre-existing ventricular dysfunction ; therefore , careful observation and close collaboration between the practicing endocrinologist and cardiologist is often required .
Continued on page 43
40 CardioSource WorldNews : Interventions November 2016