Effects of glibenclamide on ventricular fibrillation in non-insulin-dependent diabetics with acute myocardial infarction.

BACKGROUND: Glibenclamide, a hypoglycemic sulfonylurea, has shown antiarrhythmic effects in acutely ischemic myocardium. The aim of the present study was to evaluate the effectiveness of the drug in preventing ventricular fibrillation in diabetic patients with acute myocardial infarction. METHODS: We studied 232 patients with non-insulin-dependent diabetes mellitus (106 on glibenclamide, group A1; 126 treated with another hypoglycemic drug or with diet only, group A2) and 830 non-diabetic people. All the patients were admitted to our coronary care unit with their first myocardial infarction. RESULTS: Ventricular fibrillation occurred in 1.9% of group A1, 7.9% of group A2, and 9.9% of the non-diabetic (A1 versus A2, P < 0.05; A2 versus the non-diabetic group, NS; A1 versus the non-diabetic group, P < 0.01). Sustained ventricular tachycardia was not significantly different among the groups. CONCLUSIONS: The antiarrhythmic effectiveness of glibenclamide might be related to its blocking action on the ATP-dependent potassium channel, with consequent attenuation of the efflux of potassium induced by ischemia. We also observed a higher mortality rate resulting from heart failure in group A2 than in group A1 or the non-diabetic group. Since glibenclamide has never shown significant effects on myocardial contractility, this finding remains to be elucidated. Glibenclamide therefore appears to have an antifibrillatory effect in acute myocardial infarction; with respect to acute coronary events, the drug might be able to prevent ventricular fibrillation, which is most often fatal when it occurs before hospitalization.

Determination of agreement between cardiopulmonary and standard ECG stress testing in coronary artery disease.

The agreement between the results of standard ECG (CX) and cardiopulmonary (CPX) exercise stress tests performed in randomized sequence was evaluated in 40 patients with known coronary artery disease but who were not taking cardioactive therapy. Systolic blood pressure and heart rate were significantly higher during CPX only at low workload (less than 100 W). Exercise time and rate-pressure product at both peak exercise and ischaemic threshold were not significantly different between the two tests, even though their variability exceeded the value of 20%, which is generally accepted as the cut-off point for defining CX parameters as reproducible. However, the metabolic response to exercise, assessed by means of blood lactate kinetics analysis, was highly reproducible between the two tests. We conclude that the provocative role of exercise testing is not altered by the gas exchange analysis technique used in CAD patients. However, the common indexes of myocardial as well as of global physical performance may be influenced, thus requiring caution in comparing data with those derived from CX or from reference values.

Clinical correlation between diabetic and non diabetic patients with myocardial infarction.

We have studied 130 patients with diabetes mellitus and 455 patients without. All the patients were consecutively admitted to our Coronary Care Unit with their first myocardial infarction. We have observed a higher incidence of heart failure, in-hospital mortality, atrial fibrillation, conduction abnormalities, and post-infarction angina among diabetics. Nevertheless, diabetic patients do not show evidence of larger infarcts than those without diabetes. In our patients the higher mortality among diabetics is related to an increased occurrence of left ventricular failure. Moreover, post-infarction ischemic episodes are more common compared with non diabetics. Since infarcts in diabetics do not seem to be more extensive than in non diabetics, we suggest, in accordance with others, that the poorer outcome among diabetic patients with AMI could be related to an underlying cardiac dysfunction of diabetics in addition to coronary artery diseases.

[The electrocardiogram in hypothermia]. / L'elettrocardiogramma nell'ipotermia.

Hypothermia is reflected in the electrocardiogram in the form of alterations that permit early recognition of the condition. In fact the electrocardiogram is a more sensitive indicator of temperature than the standard measurements of body temperature used in clinical practice. The various aetiological aspects of hypothermia are described as are its electrocardiographic features.

[Left ventricular behaviour before and after left anterior descending coronary artery bypass graft. M-mode echocardiographic study in 30 patients (author's transl)]. / L'ecocardiogramma del ventricolo sinistro prima e dopo by pass aorto-coronarico. Studio M-mode in 30 pazienti.

30 coronary artery disease (CAD) patients (pts) were studied by echocardiography before and after left anterior descending (LAD) coronary bypass graft in order to evaluate left ventricular (LV) behaviour. Echocardiograms were recorded early pre- (48 hours) and post-operatively (mean 12 days) and at a mean distance of 12 months (6 to 15) after operation. The following parameters were considered: left ventricular end diastolic dimension (LVDD), right ventricular diastolic dimension (LVDD), right ventricular diastolic dimension (RVDD), diastolic thickness, systolic thickening and motion of the interventricular septum (IVS) and of the LV posterior wall (LVPW). 21 pts (70%) showed reduced systolic thickening (RST less than or equal to 30%) and 17 (57%) reduced systolic motion (RSM less than or equal to 3 mm) of the septum. Before surgery no patient showed IVS paradoxical movement, left bundle branch block, valvular regurgitation, shunt, LV aneurysm. A previous myocardial infarction was present in the story of 7 pts: anterior location in 4 pts, inferior in 3 pts. Soon after operation (mean 12 days) 4 pts showed normal IVS motion; in 7 pts it was reduced (less than or equal to 3 mm) and in 19 IVS was paradoxical. In 15 pts of this last group LVPW motion resulted remarkably increased after the bypass graft. The other echo parameters didn't show significant variation. Averaging 12 months after operation, IVS systolic thickening resulted normal in 21 of the 30 pts. (70%); in 14 of the last group of 21 there was a RST preoperatively. IVS motion resulted normal in 21 of the 30 pts (70%), reduced in 5 (17%), paradoxical in 4 (13%). LVPW motion returned to the preoperative value in all but 3 pts, in whom it remained elevated. The other echo parameters didn't show any significant variation. We conclude that: 1) IVS paradoxical motion is frequently recorded by echo shortly after coronary bypass graft surgery. 2) In most pts it is accompanied by an increased excursion of LVPW, probably compensatory in origin. Both tend to normalize within few months in most of the subjects.

[Value of echocardiography in the diagnosis of dissecting aneurysm of the aorta]. / Validita' dell'ecocardiografia nella diagnosi di aneurisma dissecante dell'aorta.

A revision of 1300 echocardiograms of adults showed 14 patients whose echocardiographic diagnosis of aortic root dissecting aneurism (D.A.). Of these, 8 didn't have any anamnestic, clinical or instrumental evidence of D.A. In the other 6, admitted to our department with a suspected D.A., echocardiography proved to be useful in confirming such diagnosis in 4, in excluding it in 1, but gave a false positive diagnosis of D.A. in the sixth, affected by a diffuse carcinomatosis with pleuropericardial blood effusion. From the examination of the present experience, the Authors deem echocardiography is a useful diagnostic tool in the screening of D.A. when the following conditions are fulfilled: 1) presence of all the major criteria of Nanda and Gramiak, especially the aortic root anterior wall dilatation beyond 16 mm; 2) an almost suggestive story and clinical evidence of D.A. The usefulness of an echocardiographic pattern recently described as diagnostic of D.A. (loss of continuity between the borders of the anterior aortic wall with interventricular septum, and/or posterior aortic wall with mitral anulus) was confirmed: it was detected in 3 of the 4 D.A. patients but in none of the others. The presence of a false positive and the possibility of technical artifacts nevertheless induce caution in the interpretation of the echocardiographic pattern alone.

[A correlative study of the evolution of myocardial infarction using 131Cs scintigraphy and ecocardiography (author's transl)]. / Studio correlativo dell'evoluzione dell'infarto miocardico mediante la scintigrafia con 131Cs e l'ecocardiografia

21 patients with acute myocardial infarction (A.M.I.) were studied by echocardiography (Echo) and 131CS myocardial scintigraphy (M.S.). Some months after discharge from Hospital (mean value = 10 months), the echocardiograms and myocardial scintigrams were taken again. M.S. resulted modified in 13 patients (62%); in 7 of these there was a reduction of the "cold" area due to M.I.; in 6 an extension with scintigraphic pattern of left ventricular aneurysm was shown. Echo showed in the first group of 7, with normal ventricular cavity (L.V.C.), dimension and good movement of the walls affected by A.M.I. In the second group of 6, L.V.C. dilatation (mean value = 5,6 cm) and reduction of L.V. walls movements gave noticeable results. In the patients (8 = 38%) with unchanged M.S., Echo showed an L.V.C. dimensions increase and L.V. wall movement reduction. The most important results of the present study is the sensitivity of the M.S. and Echo to picking up left ventricular aneurysm by means of non-invasive techniques. The Authors emphasize the availability of Echo and M.S. in the follow up of M.I.