Cardiomyopathic syndrome due to coronary arter disease. II: Increased prevalence in patients with diabetes mellitus: a matched pair analysis

Coronary artery spatial distribution of chronic total occlusions: Insights from a large US registry

OBJECTIVE

To assess the spatial distribution of chronic total occlusions (CTOs) within the coronary arteries and describe procedural strategies and outcomes during CTO percutaneous coronary intervention (PCI).

BACKGROUND

Acute occlusions due to plaque rupture tend to cluster within the proximal third of the coronary artery.

METHODS

We examined the clinical and procedural characteristics of 1,348 patients according to lesion location within the coronary tree.

RESULTS

A total of 1,369 lesions in 1,348 patients (mean age 66 ± 10 years, 85% male) were included. CTO PCI of proximal segments (n = 633, 46%) was more common than of mid (n = 557, 41%) and distal segments (n = 179, 13%). Patients undergoing CTO PCI of proximal segments were more likely to be smokers (P < 0.01), have prior coronary artery bypass graft surgery (P = 0.03) and lower ejection fraction (P = 0.04). CTOs occurring in proximal segments had longer length (P <0.01), proximal cap ambiguity (P < 0.01), and moderate/severe calcification (P < 0.01) compared to mid or distally located CTOs. Interventional collaterals were more often present in CTO PCI of proximal segments (64%, 53%, 56%, P < 0.01) consistent with the higher use of retrograde approach (47%, 33%, 37%, P < 0.01) relative to antegrade wire escalation (67%, 82%, 82%, P < 0.01). Procedural complexity was higher in CTO PCI of proximal segments (vs. mid and distal): contrast volume= 275 ml (200-375), 260 ml (200-350), 250 ml (175-350), P = 0.01; fluoroscopy time 53 minutes (32-83), 39 minutes (24-65), 40 minutes (22-72), P < 0.01. However, procedural success (87%, 90%, 85%, P = 0.1), technical success (89%, 91%, 88%, P = 0.24), and complications rates (2.8%, 2.5%, 2.2%, P = 0.88) were not different.

CONCLUSIONS

The most common target vessel location for CTO PCI is the proximal coronary segment. PCI of proximal occlusions is associated with adverse clinical and angiographic characteristics and often requires use of the retrograde approach, but can be accomplished with high procedural and technical success and low complication rates. © 2016 Wiley Periodicals, Inc.

Factors associated with false-negative cardiovascular magnetic resonance perfusion studies: A Clinical evaluation of magnetic resonance imaging in coronary artery disease (CE-MARC) substudy

Purpose

To examine factors associated with false‐negative cardiovascular magnetic resonance (MR) perfusion studies within the large prospective Clinical Evaluation of MR imaging in Coronary artery disease (CE‐MARC) study population. Myocardial perfusion MR has excellent diagnostic accuracy to detect coronary heart disease (CHD). However, causes of false‐negative MR perfusion studies are not well understood.

Materials and Methods

CE‐MARC prospectively recruited patients with suspected CHD and mandated MR, myocardial perfusion scintigraphy, and invasive angiography. This subanalysis identified all patients with significant coronary stenosis by quantitative coronary angiography (QCA) and MR perfusion (1.5T, T₁‐weighted gradient echo), using the original blinded image read. We explored patient and imaging characteristics related to false‐negative or true‐positive MR perfusion results, with reference to QCA. Multivariate regression analysis assessed the likelihood of false‐negative MR perfusion according to four characteristics: poor image quality, triple‐vessel disease, inadequate hemodynamic response to adenosine, and Duke jeopardy score (angiographic myocardium‐at‐risk score).

Results

In all, 265 (39%) patients had significant angiographic disease (mean age 62, 79% male). Thirty‐five (5%) had false‐negative and 230 (34%) true‐positive MR perfusion. Poor MR perfusion image quality, triple‐vessel disease, and inadequate hemodynamic response were similar between false‐negative and true‐positive groups (odds ratio, OR [95% confidence interval, CI]: 4.1 (0.82–21.0), P = 0.09; 1.2 (0.20–7.1), P = 0.85, and 1.6 (0.65–3.8), P = 0.31, respectively). Mean Duke jeopardy score was significantly lower in the false‐negative group (2.6 ± 1.7 vs. 5.4 ± 3.0, OR 0.34 (0.21–0.53), P < 0.0001).

Conclusion

False‐negative cardiovascular MR perfusion studies are uncommon, and more common in patients with lower angiographic myocardium‐at‐risk. In CE‐MARC, poor image quality, triple‐vessel disease, and inadequate hemodynamic response were not significantly associated with false‐negative MR perfusion. J. MAGN. RESON. IMAGING 2016;43:566–573.

Alterations in connexin 43 during diabetic cardiomyopathy: competition of tyrosine nitration versus phosphorylation

BACKGROUND

Cardiac conduction abnormalities are observed early in the progression of type 1 diabetes (T1D), but the mechanism(s) involved are undefined. Connexin 43, a critical component of ventricular gap junctions, depends on tyrosine phosphorylation status to modulate channel conductance; changes in connexin 43 content, distribution, and/or phosphorylation status may be involved in cardiac rhythm disturbances. We tested the hypothesis that cardiac content and/or distribution of connexin 43 is altered in a rat model of T1D cardiomyopathy, investigating a mechanistic role for tyrosine.

METHODS

Electrocardiographic analyses were conducted during the progression of diabetic cardiomyopathy in rats dosed with streptozotocin (STZ; 65 mg/kg) 3, 7, and 35 days after the induction of diabetes. Following functional analyses, we conducted immunohistochemical and immunoprecipitation studies to assess alterations in connexin 43.

RESULTS

There was significant evidence of ventricular conduction abnormalities (QRS complex, Q-T interval) as early as 7 days after STZ, persisting throughout the study. Connexin 43 levels were increased 7 days after STZ and remained elevated throughout the study. Connexin 40 content was unchanged relative to controls throughout the study. Changes in connexin 43 distribution were also observed: connexin 43 staining was dispersed from myocyte short axis junctions. Connexin 43 tyrosine phosphorylation declined during the progression of diabetes, with concurrent increases in tyrosine nitration.

CONCLUSIONS

The data suggest that changes in connexin 43 content and distribution occur during experimental diabetes and likely contribute to alterations in cardiac function, and that oxidative modification of tyrosine-mediated signaling may play a mechanistic role.

Heart failure in the diabetic patient

This review examines the extent of the increased rate of heart failure (HF) in the diabetic patient, along with the possible causes for this increase and the poor prognosis associated with HF. Also reviewed are the therapies that are available for the treatment of diabetic HF and whether intensifying the use of these therapies might improve the worsened clinical outcomes for the patient who has diabetes.

Heart failure: the frequent, forgotten, and often fatal complication of diabetes

There is a high frequency of heart failure (HF) accompanied by an increased mortality risk for patients with diabetes. The poor prognosis of these patients has been explained by an underlying diabetic cardiomyopathy exacerbated by hypertension and ischemic heart disease. In these patients, activation of the sympathetic nervous system results in increased myocardial utilization of fatty acids and induction of fetal gene programs, decreasing myocardial function. Activation of the renin-angiotensin system results in myocardial remodeling. It is imperative for physicians to intercede early to stop the progression of HF, yet at least half of patients with left ventricular dysfunction remain undiagnosed and untreated until advanced disease causes disability. This delay is largely because of the asymptomatic nature of early HF, which necessitates more aggressive assessment of HF risk factors and early clinical signs. Utilization of beta-blockade, ACE inhibitors, or possibly angiotensin receptor blockers is essential in preventing remodeling with its associated decline in ventricular function. beta-Blockers not only prevent, but may also reverse, cardiac remodeling. Glycemic control may also play an important role in the therapy of diabetic HF. The adverse metabolic side effects that have been associated with beta-adrenergic inhibitors in the diabetic patient may be circumvented by use of a third-generation beta-blocker. Prophylactic utilization of ACE inhibitors and beta-blockers to avoid, rather than await, the need to treat HF should be considered in high-risk diabetic patients.

[Effect of captopril on left ventricular diastolic dysfunction in young insulin dependent diabetic patients with microalbuminuria]

BACKGROUND

Diabetic cardiomyopathy (DMC) is a complication of diabetes mellitus (DM)that is more frequently observed in those patients with microalbuminuria. Left ventricular diastolic dysfunction (LVDD) in patients with diabetes, in absence of another etiology that justifies it, is an early marker of DMC. We carried out a prospective study on young diabetic type 1 patients with microalbuminuria, aimed at knowing the effect of captopril on LVDD.

PATIENTS AND METHOD

We included 30 patients (18 males and 12 females) diagnosed with type 1 DM,aged 40 years old, who had been recently found to have microalbuminuria and thus they were candidates to receive captopril. We excluded patients having factors different from DM that could modify the diastolic function. All patients underwent a complete biochemical and echocardiographic study before starting the treatment with captopril and six months later. A diagnosis of LVDD was made when at least one of the following parameters was present in the echocardiographic study: isovolumetric relaxing time (IRT) >100 ms, deceleration time (DT) > 220 ms or early filling rate peak/late filling rate peak ratio (E/A) < 1. According to the results of the second echocardiogram, patients were classified in two groups: improved group (when there was at least a 10% improvement of initial LVDD altered parameters) and non-improved group. A control group of 28 type 1 diabetic patients without microalbuminuria who were not given captopril was included (group C).

RESULTS

The initial echocardiographic study yielded 11 patients having a normal diastolic function (group FDN) and 19 patients having LVDD (group FDA). After 6 moths of captopril treatment, an improvement of the ratio E/A was observed in the group FDN: from 1.58 (0.36)in the beginning to 1,68 (0.29) six moths later (p < 0.05),and in the group FDA: from 1.09 (0.24) to 1.24 (0.28) (p <0.05). In the group FDA, an improvement of IRT was found: from 110 (16) ms to 99.9 (9.6) ms (p < 0.01). Moreover, in the group FDA, LVDD improved after sixth months in 15 (78.9%) patients but not in 4 (21,6%). This LVDD improvement was associated with a decrease of the diastolic blood pressure (DBP) and the systolic blood pressure (SBP) at the end of the study. A logistic regression analysis showed an independent association between the reduction of the mean SBP and the improvement of LVDD.

CONCLUSION

Our results suggest that captopril can improve LVDD in young patients with type 1 diabetes and microalbuminuria, possibly due to a decrease of blood pressure.

[Left ventricular diastolic dysfunction in young people with type 1 diabetes mellitus. Associated factors]

AIM

The aim of our study was to evaluate left ventricular function of diastolic in young (< 40 years) asymptomatic patients with type 1 diabetes mellitus free of cardiovascular disease symptoms and to analyze the associated factors to the left ventricular diastolic dysfunction (LVDD) in these patients.

PATIENTS AND METHODS

Thirty-five type-1 diabetic patients (mean age 27.8+/-7.5 years) old and 54 healthy controls (mean age 26.1+/-4.1 years) were studied. Anamnesis, physical exploration, general analytical studies, microalbuminuric and Doppler-echocardiographic studies were performed.

RESULTS

The LVDD was present in 13 (37.1%) of the diabetic patients and none of the control patients. The ratio of peak early to peak late (atrial) filling velocity was significantly decreased in diabetic compared with control subjects (1.1+/-0.3 versus 1.5+/-0.2; p<0.01). The isovolumetric relaxation time was increased in diabetic patients compared with control subjects (104+/-11 versus 79+/-11; p<0.01). Diabetics with LVDD were older aged, predominantly males, had worse glucemic control, more alteration of lipidic metabolism and higher levels of microalbuminuria, than diabetics without LVDD.

CONCLUSIONS

The LVDD is frequent in young diabetics free of cardiovascular disease symptoms. These studies suggest that because this patients were of older age, of the masculine sex with, poor glucemic control, altered lipidic metabolism, and microalbuminuria they might be a group that is associated with LVDD which, in the absence of cardiovascular disease, might be an early preclinical alteration, potentially related to subsequent development of diabetic cardiomyopathy.

Angiographic study of coronary artery disease in diabetic patients in comparison with nondiabetic patients

Diabetes mellitus is known to be a major risk factor for the development of coronary artery disease (CAD). The aim of this study was to investigate angiographically the coronary arteries of diabetic persons, focusing on the type and distribution of CAD, sex differences in CAD anatomy, and the size of the coronary vessels. This was a randomized study and included two groups of patients with angiographically demonstrated CAD. Group A included 463 diabetics, aged 60.3 years, and Group B 210 nondiabetic patients, aged 58.5 years. The two groups were matched by age, sex, weight, and classic risk factors. The authors evaluated the regional location of CAD, left ventricular (LV) function, and the width of the lumen of coronary arteries. The diabetics had three-vessel disease more frequently (p<0.001) and one-vessel disease less frequently (p<0.001). The CAD was more extensive in Group A (mean 2.2 vessels, compared to 1.8 vessels in Group B, p<0.01). The right coronary artery was affected more often in diabetics (p<0.01), as was the anterior descending artery in three-vessel disease (p<0.05). The male diabetics had the same angiographic CAD severity as the females, although the latter had a better LV ejection fraction (p<0.05). The female diabetics < 55 years old had CAD findings comparable with those from women 4 years older in Group B. Diabetics show more diffuse and severe CAD than the general population. There are no sex-related differences in the severity of CAD.

Prognosis after hospitalization for acute myocardial infarction not accompanied by typical ischemic chest pain. The Multicenter Diltiazem Postinfarction Trial Research Group

PURPOSE

Although ischemic-type chest pain generally identifies acute myocardial infarction (AMI), some patients are hospitalized for AMI without this symptom. Long-term mortality and morbidity after AMI presenting with alternative warning symptoms have not been examined previously. We therefore assessed the prognostic implications of the absence of typical chest pain as well as other recognized risk predictors in patients hospitalized with AMI.

PATIENTS AND METHODS

Data were obtained during the Multicenter Diltiazem Postinfarction Trial. Pain status and other baseline characteristics were determined prospectively by study coordinators according to simple, prespecified criteria. Patients were then examined every 3 to 4 months until trial completion. We applied chi-square methods, life-table analysis, and multivariate analysis to assess the strength and independence of prognostic power associated with each baseline variable.

RESULTS

Of 2,464 patients enrolled 3 to 15 days after enzyme-documented AMI, 115 patients lacked typical ischemic-type chest in on presentation (the "nonpainful" group). After 25 months' mean follow-up, cardiac mortality was 20% for nonpainful patients and 10% for 2,349 patients with typical pain (the "painful" group), P < 0.001. Similar increments were seen in total deaths (27% nonpainful versus 13% painful, P < 0.001) and cardiac events, namely, cardiac death or nonfatal reinfarction (24% nonpainful versus 17% painful, P = 0.001). Late congestive heart failure was more frequent (17% nonpainful versus 7% painful, P < 0.001), but unstable angina was less (6% nonpainful versus 16% painful, P = 0.005). At outset, nonpainful patients had more left ventricular dysfunction and diabetes mellitus. However, nonpainful AMI predicted worse outcome even when these problems were absent. Logistic regression confirmed greater cardiac death risk in the nonpainful group (hazard ratio = 2.05) and showed that predictive power of nonpainful status was independent of baseline ejection fraction, Holter data, concomitant diabetes mellitus, and other covariates.

CONCLUSIONS

Patients hospitalized with nonpainful AMI are much more likely to experience late cardiac death or congestive heart failure than are patients with painful AMI. In part, this probably reflects more ventricular damage with alternative warning symptoms such as dyspnea. However, our data suggest that defective perception of warning pain also provides a long-term risk to life that is independent of previously known predictors of poor outcome.

Heart rate/stroke volume relationship during upright exercise in long-term diabetics

The changes in stroke volume (SV) during upright exercise were studied in 20 insulin-dependent diabetics (IDDM) and 20 age- and sex-matched controls. None of the diabetics had any cardiovascular symptoms. In addition, tests of autonomic function were conducted in the diabetics, assessing changes in heart rate (HR) during deep breathing and the Valsalva maneuver. During exercise the SV in the controls gradually increased and then remained essentially unchanged until maximum HR was achieved. Seven of the diabetics failed to sustain an initial increase in SV (fall > 15%), eight showed a "delayed" increase in SV, and the remaining five demonstrated an increasing SV over the range from rest to peak exercise. Abnormal autonomic function results were found during deep breathing (four diabetics) and the Valsalva maneuver (four diabetics). Findings indicate that cardiac function could be abnormal in IDDM without evidence of autonomic dysfunction. This abnormality could be due to a specific cardiomyopathy.

Acute myocardial infarction in the diabetic patient: pathophysiology, clinical course and prognosis

Although there have been significant advances in the care of many of the extrapancreatic manifestations of diabetes, acute myocardial infarction continues to be a major cause of morbidity and mortality in diabetic patients. Factors unique to diabetes increase atherosclerotic plaque formation and thrombosis, thereby contributing to myocardial infarction. Autonomic neuropathy may predispose to infarction and result in atypical presenting symptoms in the diabetic patient, making diagnosis difficult and delaying treatment. The clinical course of myocardial infarction is frequently complicated and carries a higher mortality rate in the diabetic than in the nondiabetic patient. Although the course and pathophysiology of myocardial infarction differ to some degree in diabetic patients from those in patients without diabetes, much more remains to be known to formulate more effective treatment strategies in this high risk subgroup.

Stroke following acute myocardial infarction in diabetics

To investigate the effect of diabetes on stroke after myocardial infarction (MI), we studied consecutive MI patients admitted to the coronary-care unit prospectively, and compared diabetics with non-diabetics. Seven per cent (11/148) of diabetics and 3% (8/297) of non-diabetics had a stroke within 1 month after MI (P = 0.020). Previous stroke and hypertension were significant risk factors for stroke after MI in diabetics, but there were no significant risk factors in non-diabetics. Hypertension was more frequent in diabetics with (12/14; 86%) than in diabetics without (63/134; 47%) a previous stroke (P less than 0.025). Severe hypotension was more frequent in diabetics (9/11) than in non-diabetics with stroke after MI (0/8) (P = 0.002). We conclude that hypertension is a risk factor for stroke after MI in diabetics, and that may be at risk for hypotensive stroke after MI. Stroke after MI may be more frequent in diabetics than in non-diabetics.

Profile of coronary arterial disease in diabetic patients undergoing coronary arterial bypass grafting

Diabetics are believed to have more extensive and diffuse lesions of the coronary arteries in presence of coronary arterial disease. We studied prospectively 52 diabetics with coronary arterial disease who underwent coronary arterial bypass grafting and evaluated their pre-operative symptomatology, angiographic appearance of coronary arteries, coronary arterial dimensions as assessed at surgery, and the post-operative complications. These were compared to 52 age and sex matched non-diabetic controls undergoing surgery during the same period. There was no statistically significant difference in the incidence of pre-operative symptomatology or frequency of myocardial infarction in the two groups. Left ventricular angiographic findings were also comparable, as was the observation on the extent and severity of coronary arterial disease as assessed by angiography and at surgery. Hence, we recommend coronary arterial bypass grafting to diabetics with the same criteria as are applied to non-diabetics, confident that there will be no added morbidity and mortality.

Diabetic heart muscle disease

Diabetic patients may have various abnormalities in left ventricular systolic and diastolic function not attributable to coronary heart disease, hypertension or other known cardiac disease. Although the exact causes of this diabetic heart muscle disease or "diabetic cardiomyopathy" are still incompletely understood, several mechanisms may contribute to it including disturbed myocardial energy metabolism, microvascular changes, structural changes in collagen, increased myocardial fibrosis, and cardiac autonomic neuropathy. Perhaps the most typical feature of diabetic heart muscle disease is an abnormal filling pattern of the left ventricle, suggesting reduced compliance or prolonged relaxation. Left ventricular systolic function is commonly normal at rest in asymptomatic diabetic patients, but it frequently becomes abnormal during exercise. The abnormalities in left ventricular systolic function may be partly reversible along with an improvement of metabolic control of diabetes. It is not known how frequently subclinical abnormalities in left ventricular function in diabetic patients result in clinically manifest heart failure.

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.

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?

Association between the severity of diabetes mellitus and coronary arterial atherosclerosis

The relation between the severity of diabetes mellitus (DM) and the risk of significant coronary artery lesions were studied in 7,655 patients undergoing coronary arteriography for suspected coronary artery disease (CAD) between 1972 and 1982. The principal treatment regimen for DM was used to estimate the severity of DM. DM treated with insulin was defined as the most severe (n = 244), followed by DM treated with oral agents (n = 344) and with diet only (n = 380); 6,687 patients did not have DM. Severity of DM in patients with CAD (70% or greater diameter stenosis) was compared with that in control subjects without CAD (0% stenosis) for each of 9 anatomic locations (proximal, middle and distal portions of right, anterior descending and circumflex coronary arteries) using a retrospective case-control approach. The risk of CAD was highest in patients with DM treated with insulin (odds ratio estimate of the relative risk [OR = 3.0]), followed by patients with DM treated with oral agents (OR = 1.8) and lastly in those treated with diet alone (OR = 1.4). Severity of DM was a significant (p less than 0.05) independent predictor of CAD in a multivariate logistic regression model, whereas age at onset and duration of DM were not. The relative risk of CAD was the same (p greater than 0.05) for each of the 9 coronary segments. The data suggest that the risk of CAD increases with the severity of DM, which was a stronger predictor of CAD than duration of DM.(ABSTRACT TRUNCATED AT 250 WORDS)

Differentiation of ischemic from nonischemic cardiomyopathy with positron emission tomography

This study was undertaken to determine whether positron emission tomography (PET) performed after the intravenous injection of 11C-palmitate permits differentiation of patients with ischemic from those with nonischemic dilated cardiomyopathy. PET was performed after intravenous injection of 11C-palmitate in 10 patients with ischemic and in 10 with nonischemic dilated cardiomyopathy. Regions of homogeneously severely depressed accumulation of 11C-palmitate, representing 15% or more of the expected myocardial cross-sectional area, were observed in 8 of 10 patients with ischemic but in none of 10 patients with nonischemic cardiomyopathy. Patients with nonischemic cardiomyopathy had marked spatial heterogeneity of the accumulation of palmitate throughout the left ventricular myocardium, whereas most tomographic sections from patients with ischemic cardiomyopathy accumulated 11C-palmitate more homogeneously in regions exclusive of discrete defects indicative of remote infarction. Thus, a larger number of discrete noncontiguous regions (17 +/- 5 compared with 12 +/- 4, p less than 0.001) and greater reduction of average 11C-palmitate content (59 +/- 6 compared with 64 +/- 10% maximal myocardial radioactivity, p less than 0.05) were seen in the tomographic reconstructions from patients with nonischemic than in those from patients with ischemic cardiomyopathy. These findings support the hypothesis that multiple myocardial infarctions underlie the process seen as dilated cardiomyopathy in patients with coronary artery disease. Our findings indicate that PET permits differentiation of patients with ischemic from those with nonischemic cardiomyopathy.

Relation of hemoglobin A1 and blood glucose to cardiac function in diabetes mellitus

To examine the relation of short- and long-term changes in glucose metabolism to cardiac function, radionuclide cineangiography and echocardiography were performed in 10 young insulin-dependent diabetic patients without clinical evidence of heart disease. Cardiac assessments were performed before and after both acute variations in blood glucose, and induction of chronic "tight glucose control" involving normalization of hemoglobin A1 concentrations. In diabetic patients, left ventricular (LV) ejection fraction (EF) at normal blood glucose concentration was indistinguishable from values in 11 normal subjects. However, during hyperglycemia (about 300 mg/dl), the average EF at rest was 61%, significantly higher than that during normoglycemia (56%, p less than 0.001). No significant change in LV diastolic dimension was noted in association with shifts between high and normal blood glucose concentrations. Normalization of hemoglobin A1 was achieved within 6 to 25 weeks. This alteration had no significant effect on LVEF, mitral valve E-F slope, or the response of systolic function to blood glucose levels. In addition, no correlation was found between LVEF and hemoglobin A1 concentrations in 4 of 5 evaluation periods. Thus, in young insulin-dependent diabetic patients without overt heart disease, variation in blood glucose concentration is associated with small but significant variation in EF at rest; normalization of hemoglobin A1 has no significant effect on LVEF or the response of systolic function to blood glucose levels.

Diabetic cardiomyopathy

Diabetes mellitus is associated with a specific cardiomyopathy. This is evident from the clinical-pathological work and the epidemiologic data from the Framingham study. Noninvasive studies of diabetics have shown alterations in systolic and diastolic function that may ultimately lead to clinical heart failure. The relationship of these cardiac changes to the type of diabetes, its duration, and its severity is not settled. However, a correlation between changes in heart function and other complications of diabetes has been demonstrated. Insufficient prospective data is available from noninvasive studies to establish the frequency of progression from subclinical cardiac dysfunction to overt congestive failure. The pathogenesis of this disorder is still uncertain. Pathological studies have shown changes in the intramural arteries, arterioles, and capillaries but their functional significance is uncertain. Experimental studies have shown interstitial changes leading to an apparently less compliant left ventricle in the diabetic dog and monkey. In the diabetic rat reversible changes were found in myocardial function, related to changes in contractile proteins and intracellular calcium metabolism. In both species, the response to anoxia or ischemia was altered in the presence of diabetes. However, irreversible depression of the contractile element was not found in most animal studies of isolated diabetes. In contrast, the combination of hypertension and diabetes leads to substantial cardiac damage and circulatory congestion, both in clinical and experimental investigations. Clearly much more work must be carried out to understand the pathogenesis, treatment, and ultimately the prevention of diabetic cardiomyopathy.

Diabetic myocardial alterations in ultrastructure and function

Myocardial samples taken from six healthy and six alloxan-diabetic dogs by means of percutaneous needle-biopsy were investigated electronmicroscopically. Specific increase in the number of collagen fibers and that of mitochondria were demonstrated beside the widening of Z bands. In the same experimental animals, a close, inverse correlation was detected (y = 0.0068x + 0.1680; r = 0.8648; F = 29.6705; n = 12) between the values of the left ventricular passive elastic modulus and those of the plasma glucose disappearance rate determined immediately before the haemodynamic investigation. On the basis of the ultrastructural findings, the proliferation of collagen fibers can be made also responsible for functional disorder of the diabetic myocardium.

Non-invasive assessment of left ventricular function in diabetics without clinical heart disease

Left ventrical performance was assessed by systolic and diastolic time intervals measured echocardiographically in 24 diabetic patients without clinical heart disease and in 18 healthy subjects. It was found that diabetics had longer PEP, higher PEP/LVET ratio and longer IVRT (p less than 0.01). The possible pathogenetic explanations of these abnormalities are discussed and it is concluded that the measurement of time intervals is a useful method for detecting this myocardial dysfunction on the preclinical stage.

Left ventricular function in diabetes mellitus. II: Relation between clinical features and left ventricular function

We have shown a close relation between clinical microvascular complications and abnormalities of left ventricular function in 185 established diabetics without clinical heart disease. In 50 insulin-dependent diabetics who presented at under 20 years of age there was a correlation between the duration of diabetes and the isovolumic relaxation time, minimal dimension to mitral valve opening, and ratio of pre-ejection period to left ventricular ejection time. Diabetics with mild microvascular complications were similar to diabetics with no complications except for minor prolongation of the diastolic time intervals. Those with severe complications were significantly different from diabetes with milder complications and normal controls in all variables of left ventricular function. A close relation between left ventricular function and the microvascular complications index (code 0 when no complications to code 7 when all present and severe) was found for the following variables: isovolumic relaxation time, the interval from minimal dimension to mitral valve opening, ratio of pre-ejection period to left ventricular ejection time, and pre-ejection period index. It is concluded that in diabetes abnormalities of left ventricular function are related to duration of disease and complications; and that a diabetic specific heart muscle disorder occurs frequently in patients with severe microvascular complications.

Non invasive evaluation of left ventricular performance in 294 diabetic patients without clinical heart disease

The authors studied the modification of systolic time intervals (STI), pre-ejection period (PEP) and left ventricular ejection time (LVETc), before and after isometric exercise, in 294 diabetic patients without clinical evidence of cardiomyopathy and in good metabolic control compared to 132 normal subjects. The study was aimed at detecting preclinical alterations of left ventricular function. Diabetic patients considered together did not show any difference in STI in basal conditions or after isometric exercise compared to normal subjects. When diabetic patients were divided into sub-groups according to their treatment, the insulin-treated diabetics showed modification of STI after isometric exercise, which indicated an alteration of left ventricular function. Also subjects treated with oral hypoglycemic agents showed similar but less evident changes. In diabetic patients on diet only and in those with duration of diabetes of 6 months or less, STI was identical to that of normal subjects. These data do not explain the pathogenesis of myocardial involvement, although they are in accordance with studies which have laid emphasis on the alteration of compliance of the diabetic heart.

Cardiomyopathic syndrome caused by coronary artery disease. III: Prospective clinicopathological study of its prevalence among patients with clinically unexplained chronic heart failure

Each day, for one year, the medical records of adult patients who died in hospital were reviewed before seeing the necropsy findings. For those patients who had had chronic left or left and right heart failure, a presumptive cause was assigned on the basis of antemortem clinical data. Of 740 consecutive patients who were studied at necropsy, 90 had had chronic heart failure. In 15 patients the cause of heart failure was not apparent by clinical criteria; of these, 7 were found at necropsy to have cardiomyopathic syndrome caused by coronary artery disease. In retrospect, the presence of overt diabetes mellitus was a clue that cardiomyopathy caused by coronary artery disease was the cause of clinically unexplained heart failure; 5 of 7 patients with unexplained heart failure who were found to have this at necropsy were diabetic, whereas only 1 of the other 8 patients with clinically unexplained heart failure was diabetic (P less than 0.05). Patients in whom clinically unexplained heart failure was found to be the result of cardiomyopathy caused by coronary artery disease had multiple myocardial infarctions on pathological examination, which, with one exception, were nontransmural. By contrast, myocardial infarctions were transmural on pathological examination in each of 7 matched 'controls' with heart failure, in whom the diagnosis of coronary artery disease had been clinically apparent (P less than 0.01).