Increased congestive heart failure after myocardial infarction of modest extent in patients with diabetes mellitus

Silent myocardial ischemia and infarction in diabetics with peripheral vascular disease: assessment by dipyridamole thallium-201 scintigraphy

We investigated the incidence of silent myocardial ischemia and infarction as assessed by dipyridamole thallium scintigraphy in 30 diabetic patients with peripheral vascular disease and without clinical suspicion of coronary artery disease. Seventeen patients (57%) had thallium abnormalities, with reversible thallium defects compatible with ischemia in 14 patients (47%) and evidence of prior, clinically silent myocardial infarction in 11 patients (37%). Thallium abnormalities were most frequent in patients with concomitant hypertension and cigarette smoking (p = 0.001). These results suggest that unsuspected coronary artery disease is common in this particular group of patients with diabetes mellitus.

Diabetic cardiomyopathy

Diabetes mellitus is associated with an excessive cardiovascular morbidity and mortality. Although one frequently associates cardiac dysfunction with enhanced coronary atherosclerosis in diabetic patients, evidence has accumulated for the existence of a specific "diabetic" cardiomyopathy. Abundant literature evidence supports the concept of myocardial dysfunction separate from epicardial coronary disease in diabetic individuals. The relationship of myocardial dysfunction to the type, duration, and treatment of diabetes awaits further delineation. The relative pathogenic significance of the multiple factors that may alter myocardial performance in diabetic patients similarly awaits further elucidation.

Coronary blood flow in chronic insulin-dependent diabetic dogs

Diabetic patients appear to be at an increased risk for perioperative morbidity and mortality following coronary artery bypass grafting. Many have suggested that microangiopathy is a primary cause. Using radionuclide labelled microspheres, we measured the perfusion of the subendocardium, midmyocardium, subepicardium, and the subendocardium/subepicardium ratio in alloxan-induced diabetic and normal dogs. We found no statistical difference in the myocardial perfusion of dogs made diabetic for five months when compared to normal dogs. By using repeated measures two-factor analysis of variance-regression model, changing blood glucose levels had no effect on coronary blood flow in either the diabetic or normal dogs.

Diabetic heart disease: the clinical and pathological spectrum--Part I

Diabetes mellitus is a significant condition affecting major segments of all population groups studied. With the introduction of insulin and oral hypoglycemic therapy, and with better understanding of diet and weight control over the past half century, the primary causes of diabetic morbidity and mortality have shifted in varying proportions from metabolic derangements, infection, and renal insufficiency to different types of cardiovascular disease. Despite extensive clinical and laboratory research on the etiology, pathogenesis, and even the existence of cardiovascular disease associated with diabetes mellitus, however, considerable debate is still apparent in this field. Our purpose is to present an overview of the subject of diabetic heart disease, with a critical analysis of epidemiologic, clinical, and pathological data. Some of this material will be addressed from the perspective of research in this area over the past decade by one of us (SMF), particularly in experimental hypertensive and diabetic cardiomyopathy. However, overall, an attempt will be made to provide an objective and balanced analysis, in order to answer the question: does diabetic heart disease exist?

The effect of diabetes mellitus on prognosis and serial left ventricular function after acute myocardial infarction: contribution of both coronary disease and diastolic left ventricular dysfunction to the adverse prognosis. The MILIS Study Group

Patients with diabetes mellitus experience a more adverse outcome after acute myocardial infarction compared with nondiabetic patients, although the mechanisms responsible for these findings are not clear. From the Multicenter Investigation of the Limitation of Infarct Size (MILIS) study, the course of acute infarction in 85 diabetic patients was compared with that in 415 nondiabetic patients, all of whom had serial assessments of left ventricular function. The diabetic patients experienced a more complicated in-hospital and postdischarge course than did the nondiabetic patients, including a higher incidence of postinfarction angina, infarct extension, heart failure and death, despite the development of a smaller infarct size and similar levels of left ventricular ejection fraction. Although diabetic patients had a worse profile of cardiovascular risk factors at the time of the index infarction, the increased incidence of adverse outcomes among them persisted despite adjustment for these baseline imbalances. Diabetic women had a poor baseline risk profile compared with the other groups categorized by gender and diabetic status, and experienced an almost twofold increase in cardiac mortality despite development of the smallest infarct size during the index event. The duration of diabetes and the use of insulin at the time of the index infarction were associated with a better in-hospital mortality rate, but the duration of diabetes did not exert a major influence on the outcome of the diabetic patients. The factors responsible for the increased incidence of adverse outcomes among diabetic patients may be related to an acceleration of the atherosclerotic process, diastolic left ventricular dysfunction associated with diabetic cardiomyopathy or other unidentified unfavorable processes.

Cardiac disease in diabetes

The current approach to cardiac disease recognizes that the cardiovascular problems of diabetic patients have both a coronary artery atherosclerotic component and an independent myocardial component. The presence of the myocardial component has become more apparent in recent years, and a full understanding of the balance between the two components is necessary for proper treatment of the cardiac problems of patients with diabetes.

Acute myocardial infarction in diabetes mellitus and significance of congestive heart failure as a prognostic factor

Diabetes mellitus has been associated with high mortality rates in patients with acute myocardial infarction (AMI). To better define prognosis in this population, the clinical course of 183 diabetics with AMI was studied. In-hospital mortality for all patients was 28% (52 of 183 patients). Mortality was significantly higher in patients with prior AMI than in patients without prior AMI (41 vs 18%, p less than 0.01) and was significantly higher in women than in men (37 vs 19%, p less than 0.01). The 2-fold increase in mortality among diabetic women was observed both in patients with and without prior AMI. The excess mortality among diabetic women was attributable to their increased risk for severe congestive heart failure (CHF) and cardiogenic shock. Death due to CHF occurred in 22% of all diabetic women with AMI compared with 6% of the diabetic men (p less than 0.01). Death resulting from complications other than CHF was similar for both sexes. There were no male-female differences in the history of prior AMI, systemic hypertension, obesity, nephropathy, frequency of Q-wave AMI, anterior AMI or peak creatine kinase levels to account for the high risk for CHF in diabetic women. It is therefore concluded that diabetic women with AMI are at increased risk for death due to CHF, and that this risk is not readily attributable to known conditions associated with CHF.

Myocardial infarction in old people. The influence of diabetes mellitus

The clinical features and outcome were determined for 100 consecutive patients aged 65 years or older with a history of diabetes mellitus who presented to hospital with acute myocardial infarction. Each case was compared with an age- and sex-matched nondiabetic control also admitted to hospital with acute myocardial infarction. Chest pain was equally common in both groups and was the main presenting symptom. Cardiac failure was a more frequent accompaniment in the diabetics, despite the lack of evidence for greater infarct size in this group. The outcome was worst for female diabetics, of whom 46% died. Contrary to popular teaching, painless myocardial infarction is not a specific feature of elderly diabetics.

Raised concentrations of glucose and adrenaline and increased in vivo platelet activation after myocardial infarction

Plasma concentration of beta thromboglobulin was used as an index of in vivo platelet activation in 36 patients after acute myocardial infarction. Twelve patients had diabetes, seven had pulmonary oedema or cardiogenic shock (pump failure) or both, and 17 had uncomplicated infarcts. On the first day of admission, concentrations of beta thromboglobulin were higher in the patients with diabetes and those with pump failure than in those with uncomplicated infarcts. Concentrations of beta thromboglobulin in the non-diabetic patients were studied by multiple regression analysis and were significantly associated with plasma concentrations of adrenaline, pump failure, and glucose but not with noradrenaline or infarct size. When all subjects were considered together, glucose, adrenaline, and pump failure were associated with the beta thromboglobulin concentration but diabetes was without significant effect. Hyperglycaemia and raised plasma adrenaline concentration after myocardial infarction may activate platelets, and this could contribute to poor outcome in such patients.

Effects of alloxan-induced diabetes on ischemia-reperfusion injury in rabbit hearts

Hearts from rabbits with 8-16 weeks of alloxan-diabetes were compared with hearts from normal rabbits to determine whether diabetic myocardium is more sensitive to ischemic injury. In isolated buffer-perfused hearts, left ventricular developed pressure, diastolic pressure, time to peak pressure (TTPP), time to half-maximal relaxation (RT1/2), and positive and negative dP/dt were measured during generation of left ventricular filling curves before and after 90 minutes of low-flow ischemia. Hearts from diabetic rabbits (blood glucose, 384 +/- 28 mg/dl, mean +/- 95% confidence limits) had left ventricular developed and diastolic pressures similar to normal hearts but exhibited significant increases in TTPP and RT1/2 with decreased positive and negative dP/dt. Left ventricular chamber volume relative to heart mass was greater in diabetic than in normal hearts. Recovery of developed pressure after ischemia was similar in normal (41 +/- 16%) and diabetic hearts (47 +/- 13%). In diabetic hearts during recovery from ischemia, TTPP and R1/2 remained increased compared with normal hearts, with positive and negative dP/dt decreased compared with normal hearts, in proportion to the preischemic differences. After ischemia, high-energy phosphates were depleted to the same extent in normal and diabetic rabbits. In coronary ligation experiments, histochemically determined infarct size in diabetic rabbits after 30 minutes occlusion and 24 hours reperfusion was similar to that in normal rabbits when adjusted for a significantly smaller heart weight and a correspondingly smaller anatomic risk region in the diabetic animals. Thus, despite characteristic abnormalities of mechanical function in diabetic hearts, the severity of injury after ischemia with reperfusion was normal for diabetic hearts.

Abnormal autonomic function in diabetic and nondiabetic patients after first acute myocardial infarction

We performed autonomic function testing in 68 patients, 34 with diabetes mellitus (group A) and 34 without (group B), at 72 h after a first acute myocardial infarction (MI) to determine the prevalence of autonomic dysfunction in these patients. Heart rate (HR) variation during 6 breaths/min obtained from mean of longest RR interval during expiration(E)/mean of shortest RR interval during inspiration (I) (E:I ratio), immediate HR response to standing = RR at 30th beat/RR at 15th beat (30:15 ratio) and postural fall of blood pressure were evaluated. In group A, 25 (78 percent) of 32 patients had an abnormal expiration-inspiration ratio compared with 28 (85 percent) of 33 in group B. Twenty-six (76 percent) patients in group A and 16 (47 percent) in group B had an abnormal 30:15 ratio. Abnormal postural fall of blood pressure was seen in 16 (47 percent) patients in group A compared with ten (29 percent) in group B. During follow-up, four women in group A with an initial autonomic dysfunction died, and in group B, three patients with a normal autonomic function died. Thus, autonomic dysfunction does not seem to contribute to the high mortality among diabetics after an acute MI.

The extent of coronary artery disease in diabetic patients with myocardial infarction: an ECG study

In 91 non-diabetics (age 63 +/- 12, mean +/- SD, years range 31-94 years) and 85 patients with known diabetes or clearly abnormal levels of HbA1c (age 66 +/- 10 years, range 36-87 years) electrocardiograms were analysed sequentially after acute myocardial infarction (AMI). There was no significant difference in infarct site between the two groups. Generalized ischaemic change without ST elevation was seen in 33% of diabetics and 22% of non-diabetics (p greater than 0.1). In patients with transmural AMI, cardiogenic shock (CGS) was significantly commoner in diabetics (relative risk 3.1, CL 1.2-8.1) but there was no difference in the frequency of reciprocal change between the two groups. In both diabetic and non-diabetic patients the development of cardiogenic shock was more frequently associated with the presence of reciprocal change, the difference reaching significance in the diabetic group (chi 2 = 4.4, p less than 0.05). Thus cardiogenic shock in both diabetic and non-diabetic patients with AMI may be associated with the presence of extensive coronary artery disease, but differences in the prevalence of extensive disease do not explain the predisposition of diabetic patients to CGS.

Myocardial infarct size and mortality in diabetic patients

The mortality rate from myocardial infarction is disproportionately high in diabetic patients. One explanation for this may be that diabetic patients incur more extensive myocardial necrosis. This possibility was examined in a three part study. Firstly, peak serum aspartate aminotransferase concentrations of all diabetic and non-diabetic patients admitted with myocardial infarction over a 16 year period were compared retrospectively. Secondly, peak aspartate aminotransferase concentrations in a series of diabetic patients and controls matched by age and sex were examined retrospectively. Thirdly, creatine kinase MB release and electrocardiographic measures of infarct size were investigated prospectively in a case/control study. Although cardiac failure and death were more common in the diabetic groups, there were no significant differences in estimates of infarct size between diabetic and non-diabetic patients in any of the studies. Therefore, the high case fatality rate amongst diabetic patients is not caused by increased myocardial damage. Presumably survival is prejudiced by factors operating before the infarction.

Myocardial infarct size and mortality in diabetic patients

The mortality rate from myocardial infarction is disproportionately high in diabetic patients. One explanation for this may be that diabetic patients incur more extensive myocardial necrosis. This possibility was examined in a three part study. Firstly, peak serum aspartate aminotransferase concentrations of all diabetic and non-diabetic patients admitted with myocardial infarction over a 16 year period were compared retrospectively. Secondly, peak aspartate aminotransferase concentrations in a series of diabetic patients and controls matched by age and sex were examined retrospectively. Thirdly, creatine kinase MB release and electrocardiographic measures of infarct size were investigated prospectively in a case/control study. Although cardiac failure and death were more common in the diabetic groups, there were no significant differences in estimates of infarct size between diabetic and non-diabetic patients in any of the studies. Therefore, the high case fatality rate amongst diabetic patients is not caused by increased myocardial damage. Presumably survival is prejudiced by factors operating before the infarction.

Myocardial infarct size and mortality in diabetic patients

The mortality rate from myocardial infarction is disproportionately high in diabetic patients. One explanation for this may be that diabetic patients incur more extensive myocardial necrosis. This possibility was examined in a three part study. Firstly, peak serum aspartate aminotransferase concentrations of all diabetic and non-diabetic patients admitted with myocardial infarction over a 16 year period were compared retrospectively. Secondly, peak aspartate aminotransferase concentrations in a series of diabetic patients and controls matched by age and sex were examined retrospectively. Thirdly, creatine kinase MB release and electrocardiographic measures of infarct size were investigated prospectively in a case/control study. Although cardiac failure and death were more common in the diabetic groups, there were no significant differences in estimates of infarct size between diabetic and non-diabetic patients in any of the studies. Therefore, the high case fatality rate amongst diabetic patients is not caused by increased myocardial damage. Presumably survival is prejudiced by factors operating before the infarction.

Myocardial infarction in the diabetic patient

It has long been thought that the symptomatology and prognosis of coronary events in patients with diabetes may differ from those in nondiabetic persons. A review of recent data demonstrates a higher mortality during the acute phase of myocardial infarction for diabetic patients than for their nondiabetic counterparts, possibly related to a higher incidence of congestive heart failure and cardiogenic shock. The clinical course of diabetic patients with infarction and the role of insulin in myocardial adaptation to ischemia are both reviewed. Diabetic patients surviving the acute phase of myocardial infarction have a lower survival in follow-up than nondiabetic survivors, although some improvement in survival has been noted following beta-adrenergic-blocker therapy.