Diabetes mellitus and myocardial infarction

In the era of thrombolytic therapy, the prognosis for patients with diabetes mellitus with myocardial infarction remains unfavorable, and the death rate from myocardial infarction in this category of patients is still significantly higher in the presence of diabetes. Increased mortality in patients with diabetes is due to various mechanisms affecting the function and blood supply of the myocardium, and the tendency to thrombosis characteristic of these patients. No less important is the late mortality due to frequent repeated heart attacks and fatal ventricular arrhythmias.

Prevention of cardiovascular diseases is an industry in which real success can be achieved. This is convincingly proved by the experience of those countries where special preventive programs are implemented. Over the past few decades, active recovery of the population, modification of lifestyles, cessation of smoking, the introduction of large-scale government programs have led to dramatic changes in the epidemiological situation regarding cardiovascular diseases and myocardial infarction, in particular in several industrialized countries. US data suggests that in 1982-1992.in comparison with the 1971-1982 biennium. A reduction in overall mortality and mortality from cardiovascular diseases was achieved , but this decrease was recorded only in persons not suffering from diabetes.

In patients with diabetes, these figures have not changed. Diabetes today is a serious problem of vascular pathology and the problem of heart disease. No need to convince practicing clinicians about how significant the risk factor is this disease. Our city cardiological center annually receives about 2.5 thousand patients with myocardial infarction, which is more than 50% of cases of myocardial infarction of the city of Kiev. Comparing the results of treatment of patients with myocardial infarction in 1984-1985. and in a later period when applying modern methods of treatment, it can be noted that the level of hospital mortality significantly decreased only in patients without diabetes. In patients with diabetes, it remains high.

Almost every fourth patient with acute large-focal myocardial infarction in combination with diabetes mellitus died, despite the fact that they all underwent modern treatment of myocardial infarction. Of course, with angioplasty and coronary stenting, the results of treatment are much more optimistic, but in this study we consider only the effect of conservative therapy of myocardial infarction. In addition, we must not forget that in Ukraine, angioplasty and coronary stenting are available only to a few, the rest of patients are treated with medication. So our numbers are quite close to the real picture of mortality in patients with myocardial infarction. Note that the numbers refer only to patients admitted to the cardiologic resuscitation unit on the first day of myocardial infarction. Therefore, our data are significantly different from the official figures, which are “diluted” with small focal myocardial infarctions, the diagnosis of which in some cases is not sufficiently reliable.

Our data take into account much more stringent criteria. Features of the course of myocardial infarction in patients with diabetes C Equal for the course of acute myocardial infarction in the group of patients with diabetes and in the group of non-diabetic patients, we noted the following features in diabetics:

  • the frequency of occurrence of arterial hypertension is higher (although there are works in which it is indicated that clinically significant arterial hypertension does not aggravate the course of myocardial infarction);
  • higher frequency of previously suffered myocardial infarction ;
  • the frequency of myocardial ruptures is much greater (this is a significant problem, because according to our clinic, the proportion of myocardial ruptures among all causes of death for Q – myocardial infarction is 20%; there is no such statistics abroad);
  • significantly higher mortality in cardiogenic shock, primary electrical instability of the ventricular myocardium, AV- blockade.

We analyzed the functional state of the myocardium in patients who arrived on the first day of the disease, selecting a group with primary Q-infarction and with a small acute left ventricular failure. Based on the main indicators (end diastolic volume, final systolic volume, ejection fraction, cardiac output), these patients were the same.

In terms of demographic indicators and localization of infarction, the groups of patients were comparable. By the end of treatment, patients without diabetes showed positive dynamics of key indicators of systolic function (the final diastolic volume and final systolic volume significantly decreased, the ejection fraction and the minute volume of the heart increased), while in diabetic patients these indicators did not change. For patients with myocardial infarction without Q wave , diabetes mellitus is also an important aggravating factor.

The transformation of this pathology of the heart in Q – myocardial infarction in patients with diabetes is observed 4 times more often. Refractory unstable stenocardia, in which patients need coronary angiography and angioplasty, is observed in 30% of diabetic patients. In search of the causes of such a severe and resistant to therapy course of myocardial infarction in patients with diabetes, we have come to interesting conclusions. The most obvious possible factors — large infarction and high frequency of three-vessel lesions — are not relevant for diabetics, paradoxically.

The frequency of anterior and posterior heart attacks in patients with and without diabetes was the same in our studies. It is known that anterior heart attacks are more extensive. This is consistent with the literature data that in diabetic patients, the mass of Q-infarction is no more than in other patients. We also failed to find convincing data in the literature that would indicate that the incidence of three-vascular lesions is higher in diabetic patients. Theoretically, diabetes should be a significant proportion of trivascular lesions. In practice, there are a number of large coronarographic studies where this could not be found. Diabetics are more pronounced disorders of neurohumoral activation (sympathetic-adrenal system is activated), endothelial dysfunction, there are pronounced hemocoagulation disorders. Special attention is given to metabolic disorders in diabetes mellitus.We studied the dynamics of glycemia in diabetics with myocardial infarction by day depending on the outcome of the disease. It turned out that the blood glucose levels of the dead and those who survived on the first day were about the same. On the second day, the glycemia of the patients who died later was significantly higher than that of the survivors. By the 4th day, the glycemia was again at the same level in both groups of patients.

I must say that this data is not our discovery. In the literature, there are results of similar studies that highlight the importance of high blood glucose for the prognosis of infarction patients. Moreover, this concerns not only diabetes mellitus, but also patients with high glycemia who did not suffer from diabetes mellitus before a heart attack, that is, with the so-called stress glycemia. Another factor that is important for the course of myocardial infarction is the fatty acid spectrum of the erythrocyte membrane. On the first day (that is, almost similar to the status before the disease, since this biochemical indicator is very inert), the content of w 3-polyunsaturated fatty acids was significantly lower in patients with acute coronary syndrome without Q wave , who died of myocardial infarction than in survivors. In this regard, an important direction of prevention of acute coronary syndrome is the therapy of w3-polyunsaturated fatty acids.

Treatment of myocardial infarction in patients with diabetes mellitus And by analyzing the results of thrombolytic therapy in patients with and without diabetes mellitus, we can note the worst effect of thrombolysis in diabetics. Hospital mortality in patients with diabetes who have received thrombolysis remains at a significant level. Also, diabetics have a much higher incidence of mild bleeding with the same number of severe bleeding during thrombolytic therapy. Diabetic retinopathy, in addition to the most severe forms, is not currently considered a contraindication to thrombolytic therapy, its safety has been reliably proven in such patients. One of the most important factors preventing effective thrombolytic therapy is the no-reflow phenomenon, in which, after recanalization of the vessels, there is no blood flow at the tissue level during the passage of infarct coronary artery. This phenomenon is observed in a fairly large number of patients with myocardial infarction. Its frequency in patients with diabetes mellitus was significantly higher, and it was noted that the higher the glycemia observed in a patient, the greater the risk of the occurrence of the no-reflow phenomenon. Thus, the treatment of myocardial infarction in patients with diabetes mellitus is a complex task. Of course, angioplasty or stenting is much more effective in patients with diabetes mellitus than thrombolytic therapy.

At the same time, both mortality and the frequency of non-fatal heart attacks are significantly reduced. Following the European recommendations, patients who have a high risk of developing complications of acute coronary syndrome should be subjected to more aggressive therapy – interventional intervention on the background of drug support. Since patients with diabetes are at extremely high risk of developing complicated forms of myocardial infarction and an unfavorable prognosis, in such patients with acute Q – myocardial infarction, it is necessary to give preference to x-surgical methods of recanalization of the coronary vessels in the first 12 hours, especially stenting. But no less important are the issues of medical approaches to the treatment of myocardial infarction , especially given the fact that the availability of early invasive therapy in our country remains extremely low and only a small proportion of patients are able to afford such treatment. Thus, issues of conservative intervention (thrombolytic therapy and complementary drugs) remain relevant even in patients at high risk, including patients with diabetes mellitus.

Given the importance of metabolic disorders in diabetes mellitus and given their significant effect on the prognosis of acute myocardial infarction, metabolic therapy is of particular importance for diabetics. Published data indicate that in the group of patients not exposed to thrombolytic therapy, the use of intravenous administration of trimetazidine significantly reduced mortality by the 35th day of treatment and the incidence of complications in the inpatient period in the absence of this effect in patients who received thrombolysis (EMIP-FR study). A few years ago, the DIGAMI study on the use of glucose-insulin-potassium mixture metabolic therapy in diabetics ended. When using 80 IU of insulin in its composition and more on the first day of myocardial infarction and continuation of insulin therapy for 1-3 months, a pronounced decrease in mortality in diabetic patients was obtained, which was especially pronounced in patients who had not previously taken insulin. Our clinic has adopted this technique, and we inject the glucose-insulin-potassium mixture on the first day of myocardial infarction , and then, equally important, all patients with diabetes mellitus (even those who before the myocardial infarction successfully corrected the glycemic level using hypoglycemic tablet preparations) translate into fractional administration (4-fold) of small doses of insulin. Such insulin therapy is desirable to maintain for several months and after discharge from the hospital.

Analyzing the effect of insulin at myocardial infarction , curious data were obtained that an important role is played not by a reduction in glycemia, but by other metabolic effects of insulin. Insulin itself, besides hypoglycemic action, has a vasodilating effect, and this speaks in favor of its use inmyocardial infarction in patients with diabetes mellitus.

The combination of insulin with acetylcholine, which is administered intracoronary, according to research, markedly improves coronary blood flow. In addition to the “discovery” of the coronary artery, we should not forget about the group of complementary drugs – ACE inhibitors. But clinicians are accustomed to believe that the effect of these drugs affects a rather long time. Subanalysis in the framework of the SMILE study showed that ACE inhibitors in patients with myocardial infarction with diabetes mellitus (the drug zofenopril was considered) compared with placebo contributed to a decrease in mortality in the first 24 hours, while in patients without diabetes mellitus this effect was not observed. Similar data were obtained for severe heart failure by 6 weeks of treatment. With early (from the first hours of Q – myocardial infarction ) the use of an ACE inhibitor in a patient myocardial infarction should always start with small doses, because there is a high risk of hypotension, aggravating hypoperfusion, which can provoke the expansion of myocardial infarction (study CONSENSUS II, K. Swedberg , 1997). Some new drugs can reduce this risk to a minimum.

In a recent study, captopril and perindopril were compared. Perindopril did not provide such a pronounced decrease in blood pressure, fraught with the risk of exacerbation of myocardial hypoperfusion, as the usual drug captopril, which indicates greater safety of perindopril. In large, multicenter, placebo-controlled studies, a decrease in mortality after myocardial infarction has been proven for such ACE inhibitors: captopril, enalapril, ramipril, zofenopril, trandolapril, lisinopril. Β – blockers are important in the treatment of patients with myocardial infarction with diabetes mellitus .

The decrease in mortality caused by them in patients with diabetes mellitus in relative terms is not less than in patients without diabetes mellitus, but the absolute number of saved lives is greater. The cardioselective β-blocker, metoprolol, was well tolerated in such patients and did not cause additional side effects. Of course, all β – blockers are not affected by the class effect, and only drugs that have proven effective in controlled clinical trials should be used (for patients with myocardial infarction, these drugs are metoprolol, timolol, propranolol and, according to a recentCAPRICORN study , carvedilol). In general, the use of modern methods of treatment with proven efficacy opens up opportunities for improving outcomes of myocardial infarction, even in patients with concomitant diabetes.

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