Oral antidiabetic treatment in patients with coronary disease: time-related increased mortality on combined glyburide/metformin therapy over a 7.7-year follow-up

BACKGROUND

A sulfonylurea--usually glyburide--plus metformin constitute the most widely used oral antihyperglycemic combination in clinical practice. Both medications present undesirable cardiovascular effects. The issue whether the adverse effects of each of these pharmacologic agents may be additive and detrimental to the prognosis for coronary patients has not yet been specifically addressed.

HYPOTHESIS

This study was designed to examine the survival in type 2 diabetics with proven coronary artery disease (CAD) receiving a combined glyburide/metformin antihyperglycemic treatment over a long-term follow-up period.

METHODS

The study sample comprised 2,275 diabetic patients, aged 45-74 years, with proven CAD, who were screened but not included in the bezafibrate infarction prevention study. In addition, 9,047 nondiabetic patients with CAD represented a reference group. Diabetics were divided into four groups on the basis of their therapeutic regimen: diet alone (n = 990), glyburide (n = 953), metformin (n = 79), and a combination of the latter two (n = 253).

RESULTS

The diabetic groups presented similar clinical characteristics upon recruitment. Crude mortality rate after a 7.7-year follow-up was lower in nondiabetics (14 vs. 31.6%, p<0.001). Among diabetics, 720 patients died: 260 on diet (mortality 26.3%), 324 on glyburide (34%), 25 on metformin alone (31.6%), and 111 patients (43.9%) on combined treatment (p<0.000001). Time-related mortality was almost equal for patients on metformin and on combined therapy over an intermediate follow-up period of 4 years (survival rates 0.80 and 0.79, respectively). The group on combined treatment presented the worst prognosis over the long-term follow-up, with a time-related survival rate of 0.59 after 7 years, versus 0.68 and 0.70 for glyburide and metformin, respectively. After adjustment to variables for prognosis, the use of the combined treatment was associated with an increased hazard ratio (HR) for all-cause mortality of 1.53 (95% confidence interval [CI] 1.20-1.96), whereas glyburide and metformin alone yielded HR 1.22 (95% CI 1.02-1.45) and HR 1.26 (95% CI 0.81-1.96), respectively.

CONCLUSIONS

We conclude that after a 7.7-year follow-up, monotherapy with either glyburide or metformin in diabetic patients with CAD yielded a similar outcome and was associated with a modest increase in mortality. However, time-related mortality was markedly increased when a combined glyburide/metformin treatment was used.

Calcium antagonists and mortality in patients with coronary artery disease: a cohort study of 11,575 patients

OBJECTIVES

This study sought to establish the risk ratio for mortality associated with calcium antagonists in a large population of patients with chronic coronary artery disease.

BACKGROUND

Recent reports have suggested that the use of short-acting nifedipine may cause an increase in overall mortality in patients with coronary artery disease and that a similar effect may be produced by other calcium antagonists, in particular those of the dihydropyridine type.

METHODS

Mortality data were obtained for 11,575 patients screened for the Bezafibrate Infarction Prevention study (5,843 with and 5,732 without calcium antagonists) after a mean follow-up period of 3.2 years.

RESULTS

There were 495 deaths (8.5%) in the calcium antagonist group compared with 410 in the control group (7.2%). The age-adjusted risk ratio for mortality was 1.08 (95% confidence interval [CI] 0.95 to 1.24). After adjustment for the differences between the groups in age and gender and the prevalence of previous myocardial infarction, angina pectoris, hypertension, New York Heart Association functional class, peripheral vascular disease, chronic obstructive pulmonary disease, diabetes and current smoking, the adjusted risk ratio declined to 0.97 (95% CI 0.84 to 1.11). After further adjustment for concomitant medication, the risk ratio was estimated at 0.94 (95% CI 0.82 to 1.08).

CONCLUSIONS

The current analysis does not support the claim that calcium antagonist therapy in patients with chronic coronary artery disease, whether myocardial infarction survivors or others harbors an increased risk of mortality.

[A severe skin reaction following mexiletene]

A 70-year-old man was treated with oral mexiletene because of ventricular premature beats due to ischemic heart disease. He developed a severe maculopapular rash which did not respond to antiallergic treatment, but disappeared after discontinuation of the drug. Adverse effects on the central nervous, cardiovascular and gastrointestinal systems have been described. A rash is rare, and in our case was of unusual severity.

[Restoration of effective artificial cardiac pacing by isoproterenol]

Since the pacing threshold of artificial pacemakers sometimes increases and causes ineffective pacing, emergency restoration of cardiac pacing may occasionally be required. In such situations sympathomimetic agents, such as isoproterenol, increase excitability and lower threshold. A 83-year-old man with acute ineffective pacing and hemodynamic instability is reported. Intravenous administration of isoproterenol restored effective, artificial cardiac pacing.

Pharmacological aspects in secondary prevention of coronary artery disease

Recent studies have demonstrated a trend toward improved survival in coronary artery disease. Contributing to this trend are advances in medical therapy. In order to evaluate the preventive effect of drugs in secondary prevention of coronary heart disease, many multi-centered trials were conducted. There is evidence that beta-adrenergic blocking agents may decrease mortality following myocardial infarction. Platelet-active drugs reduce the rate of reinfarctions and may have a beneficial effect on survival. In contrast lipid lowering agents, anticoagulants, antiarrhythmic drugs and calcium channel blockers have not shown convincing beneficial effect on the survival of patients following myocardial infarction, and further studies are required to determine the effect of the various modalities in different clinical settings.

Malignant arrhythmias in relation to values of serum potassium in patients with acute myocardial infarction

The relationship between levels of potassium in the serum and the development of malignant arrhythmias was examined in a retrospective study involving 1011 patients presenting with acute myocardial infarction. Thirteen percent of the overall patients studied had significant hypokalemia (k less than 3.5 mmol/liter). The average initial level of potassium in patients who developed malignant arrhythmias was (4.10 mmol/liter) significantly lower (P less than 0.01) than those patients who did not develop such arrhythmias (4.19 mmol/liter). To determine whether the level of potassium was, in itself, the primary cause of malignant arrhythmias following myocardial infarction, a subgroup analysis of factors influencing these levels was performed. It was determined that diabetics have a higher level of potassium than nondiabetics (4.2 mmol/liter versus 4.11 mmol/liter - P = 0.01) and a lower incidence of malignant arrhythmias (50.5% versus 63.5% - P = 0.002). No correlation was found between treatment with either digitalis or diuretics and malignant arrhythmias. Size and location of infarcted areas was found to have a direct relationship with development of arrhythmias. Size and location of infarctions, however, were not found to be related to levels of potassium in the serum. Our findings support and clarify earlier suggestions establishing the levels of potassium in the serum as an important causative factor, together with size and location of infarctions, in the development of malignant arrhythmias.

Randomized double-blind comparison of the effects of isosorbide dinitrate retard, verapamil sustained-release, and their combination on myocardial ischemic episodes

The antianginal and anti-ischemic efficacy of isosorbide dinitrate (ISDN) retard 120, verapamil 120 sustained-release (s.r.) and their combination was evaluated in 30 patients with chronic angina pectoris. The study was a randomized, double-blind crossover comparison. The evaluation was determined by exercise testing and 24-hour electrocardiographic ambulatory monitoring. The sum of ST-segment depression at comparable exercise levels was reduced by 37% (p less than 0.001) after verapamil 120 s.r. and by 45% (p less than 0.001) after combination therapy. After ISDN retard 120 the sum of ST-segment depression was also slightly reduced by 18% without attaining statistical significance. Total walking time and time to angina pectoris during treadmill exercise were significantly prolonged after all treatments. The sum of ST-segment depression in the 24-hour Holter ECG was reduced by 46% (p less than 0.001) after verapamil and by 39% (p less than 0.01) after combined therapy. After ISDN retard 120 the mean reduction was 34% (p less than 0.01). In conclusion, the result of the study indicated that ISDN retard 120, verapamil 120 s.r. and a combination of both drugs are effective in reducing the frequency and duration of ischemic episodes in patients with ischemic heart disease.

Myocardial rupture in acute myocardial infarction: urgent management

Myocardial rupture complicated acute myocardial infarction in a 50 year old man. Resuscitation was started immediately and he was treated with pericardiocentesis and a massive intravascular infusion of fluid. The torn area was plicated with Teflon felt and reinforced with an uninterrupted suture. The postoperative course was uncomplicated. This report points out the crucial importance of prompt clinical recognition and management of the acute stage of cardiac rupture in acute myocardial infarction.

Ventricular pacing as the preferable mode for long-term pacing in patients with carotid sinus syncope of the cardioinhibitory type

This study was designed to determine the efficacy of long-term VVI pacing in patients having the isolated cardioinhibitory type of carotid sinus syncope. The study included 20 patients suffering from repeated syncopal attacks; all were proven by electrophysiological studies to have isolated forms of cardioinhibitory type carotid sinus syncope. Long-term pacing by the VVI mode was carried out in all patients by programming the pacemaker rate well below the patient's sinus rate. The follow-up period after pacemaker implantation, which ranged from 2 to 54 months (average, 20 months), revealed that none of the patients had any recurrence of syncopal attack. Repeated Holter monitoring showed that ten had permanent sinus rhythm without any artificial pacing activity, while in the other ten, pacemaker activity was recorded--predominant in two patients and rare in the other eight. During Holter monitoring, attacks of weakness were reported by four patients; however, they were not related to pacemaker activity. This report indicates the importance of electrophysiological studies in patients suffering from carotid sinus syncope. These studies make possible the diagnosis of the isolated form of cardioinhibitory type syncope for which VVI pacing offers complete relief of symptomatology, thus rendering AV sequential pacing superfluous.

Carotid sinus hypersensitivity: diagnosis of vasodepressor type in the presence of cardioinhibitory type

The diagnosis of carotid sinus syncope may sometimes be difficult because its symptoms are not specific, especially in the older age group where carotid sinus hypersensitivity and syncope are not uncommon events. Of major diagnostic importance is the screening of the vasodepressor type of carotid sinus syncope in the presence of the cardioinhibitory type, as this diagnosis has important therapeutic applications. This work is based on the electrophysiological studies performed on seven men with a mean age of 61.9 years who had syncope of unknown cause and hypersensitive carotid sinus reflex. The studies revealed no evidence of sinus node dysfunction or high degree atrioventricular block that would explain the neurological symptoms. The studies also included carotid sinus stimulation with simultaneous interarterial pressure recordings with and without atrial or A-V sequential pacing. The pacing assured the maintenance of normal heart rate during carotid sinus stimulation. The results of these studies revealed that five patients suffered from cardioinhibitory type and two from a combined form of cardioinhibitory and vasodepressor type (mixed form) of carotid sinus syncope. A permanent cardiac pacemaker was implanted in the five patients with the isolated cardioinhibitory type and in one patient with the mixed type of carotid sinus syncope.

An unusual form of mitral insufficiency accompanying atrial septal defect

An unusual case of atrial septal defect secundum type, associated with intermittent severe mitral insufficiency due to billowing anterior mitral leaflet, in a 56-year old female is described. The degree of mitral insufficiency ranged from severe to none. This phenomenon manifested itself by an intermittent systolic apical thrill and intermittent mitral regurgitation on angiocardiography. Pulling the anterior mitral leaflet at operation through the atrial septal defect demonstrated that this leaflet could be caught in the left atrium, thus causing intermittent mitral insufficiency. Closure of the atrial septal defect and replacement of the mitral valve was performed.