Complex ventricular arrhythmias in patients with Q wave versus non-Q wave myocardial infarction

Mevalonate-dependent inhibition of transendothelial migration and chemotaxis of human peripheral blood neutrophils by pravastatin

Pravastatin, a hydrophilic inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, has been reported to beneficially affect atherogenesis, plaque stability, and transient myocardial ischemia in significant coronary artery disease by influencing lipid metabolism and by intracellular signaling via mevalonate pathway products other than cholesterol. Leukocytes are implicated to play a pathophysiological role in these events. We were interested in finding out whether pravastatin could affect transendothelial migration (TEM), chemotaxis, and respiratory burst activity of the neutrophil ex vivo. In addition, effects on monocyte and T-lymphocyte chemotaxis were tested. For TEM assays, monolayers of human umbilical vein endothelial cells (HUVECs) were grown to confluence on polycarbonate filters bearing 5-microns pores in Transwell (Costar) culture plate inserts. Chemotaxis experiments were performed using modified Boyden chambers with cellulose nitrate micropore filters. Respiratory burst activity was measured fluorometrically. Treatment of neutrophils and monocytes with pravastatin at 2 to 200 mumol/L and 10 to 1000 mumol/L, respectively, significantly decreased chemotaxis triggered by fMet-Leu-Phe. This effect was abolished in the presence of mevalonic acid (500 mumol/L); no effect of pravastatin was seen on T-lymphocyte chemotaxis triggered by interleukin-8. Preincubation of neutrophils with pravastatin (200 mumol/L) also resulted in a significant reduction in the number of neutrophils that transmigrated a tumor necrosis factor-stimulated or lipopolysaccharide-stimulated HUVEC monolayer. At none of the concentrations tested (2 pmol/L to 200 mumol/L) did pravastatin affect neutrophil respiratory burst activity. We conclude that pravastatin may alter monocyte chemotaxis and neutrophil-endothelial interactions in migratory responses at concentrations obtained in vivo with cholesterol-lowering doses.

Isradipine inhibits PMN leukocyte function. A possible interference with the adenosine system

The dihydropyridine derivative isradipine is able to inhibit PMN leukocyte function, such as enzyme release and free radical generation, following the activation with specific stimuli. Moreover, the drug prevents calcium influx into the cells as detected by the specific fluorescent dye FURA 2/acetoxymethylester. The specific adenosine receptor antagonist theophylline is able to partially remove the inhibiting activity, thus suggesting a possible interference of isradipine with the adenosine system. Such a cell-protecting activity adds further rationale to the employment of isradipine in those conditions, such as acute and chronic ischaemia and reperfusion damage, in which PMN leukocyte-dependent tissue injury represents a relevant pathogenetic mechanism.

Ventricular arrhythmias in patients recovering from myocardial infarction: do residual myocardial ischemia and anti-ischemic medical intervention influence the one-month prevalence? The Danish Study Group on Verapamil in Myocardial Infarction

The relationship between myocardial ischemia revealed by exercise testing and ventricular arrhythmias on Holter monitoring, and the effect of anti-ischemic intervention on the incidence of ventricular arrhythmias in patients with residual ischemia were studied in 125 patients recovering from myocardial infarction. Prior to discharge exercise testing and 24-h Holter monitoring were carried out. In patients with ST-segment depression (n = 34), ventricular arrhythmias on Holter monitoring were seen in 7 (21%) compared with 20 (22%) patients without ST-segment depression (NS). Patients were hereafter double-blindly randomized to intervention with verapamil (n = 63) or placebo (n = 62). One month after discharge, 24-h Holter monitoring was repeated. In the verapamil group ventricular arrhythmias increased from 25 to 33% (NS). In the placebo group the figures were 18 and 27%, respectively (NS). In patients with ST-segment depression and verapamil treatment, the prevalence increased from 25 to 38% (NS). In the placebo group the figures were 17 and 22%, respectively (NS). The differences between the groups were not significant. A significantly increased prevalence of ventricular arrhythmias was found in patients with either heart failure or non-Q-wave infarct. In these patients myocardial ischemia during exercise did not correlate with ventricular arrhythmias either. ST-segment depression during pre-discharge exercise testing correlated with neither the prevalence nor the incidence of ventricular arrhythmias, and anti-ischemic intervention with verapamil did not influence the incidence of ventricular arrhythmias in both patients with and without myocardial ischemia.

Survivors of acute myocardial infarction: who is at risk for sudden cardiac death?

Coronary artery disease is the leading cause of death in the United States. Approximately half of the deaths attributable to coronary artery disease are sudden cardiac deaths. A logical approach to prevention of sudden death is to identify those who are at risk and then to initiate effective therapy. Left ventricular dysfunction, frequent ventricular ectopic activity, nonsustained ventricular tachycardia, and late potentials have been identified as markers for increased risk of sudden cardiac death. The sensitivity and specificity of these risk factors vary, and the positive predictive power is less than satisfactory. The value of invasive electrophysiologic testing for risk stratification in the general postinfarction patient population remains unclear. In addition to these diagnostic difficulties, prevention of sudden death also has been limited by imperfect efficacy and potential lethal effects of the currently available antiarrhythmic agents. Automatic implantable defibrillators are effective for aborting sudden death; however, the potential for more general use of automatic defibrillators in asymptomatic but high-risk postinfarction patients has not been evaluated.

Estimation of the risk of death during the first year after acute myocardial infarction from systolic time intervals during the first week

Patients who survived for the first seven days after acute myocardial infarction were followed up for a further 51 weeks. During these 51 weeks there were 123 deaths and 477 eventual survivors. Approximately half of the deaths occurred during the first 3 weeks of follow up. The deaths were predicted with 75% sensitivity and 73% specificity by a discriminant analysis based upon six variables seen during the first 7 days; predictions of death and survival were 55% and 92% accurate respectively. These six variables were, in ascending order of prognostic importance, the occurrence of bundle branch blocks, the administration of a diuretic, the age of the patient, the presence of diabetes mellitus, a previous myocardial infarction, and the ratio of the measured left ventricular pre-ejection and ejection periods. Many other monitored variables, although univariately associated with death, contributed nothing further to the multivariate assessment of mortality risk.

Prognostic significance of the signal-averaged ECG depends on the time of recording in the postinfarction period

Serial recordings of the signal-averaged ECG and the 24-hour ambulatory ECG were obtained from 156 patients with acute myocardial infarction up to 5 days (phase 1), 6 to 30 days (phase 2), and 31 to 60 days (phase 3) after the infarction. Left ventricular ejection fraction by radionuclide ventriculography was also determined in phase 2. The signal-averaged ECG was abnormal during one or more of the three phases in 51 patients (31%). In 35 of these patients (69%) the recording changed category between normal and abnormal with the highest prevalence of abnormal recording occurring during phase 2. Eight patients had ventricular tachycardia/ventricular fibrillation in the first 48 hours after myocardial infarction. The signal-averaged ECG was abnormal in only one of these patients. Twelve patients had late arrhythmic events during the first year of follow-up (four sudden deaths and eight instances of documented ventricular tachycardia or ventricular fibrillation). Nine of the 12 patients had an abnormal signal-averaged ECG in phase 2 and four of these nine had a normal recording in phase 1. Five patients had a transient abnormal signal-averaged ECG in phase 1, whereas six patients had an abnormal recording only in phase 3. None of these 11 patients had an arrhythmic event. Stepwise logistic regression showed that an abnormal signal-averaged ECG in phase 2 has the most significant relation to late arrhythmic events. Both an abnormal signal-averaged ECG and a left ventricular ejection fraction less than 40%, but not complex ventricular arrhythmias, were independent significant risk factors for late arrhythmic events.(ABSTRACT TRUNCATED AT 250 WORDS)

Sudden cardiac death

Most sudden deaths in industrial nations are the result of underlying coronary artery disease. Longitudinal studies have demonstrated that the percent of all coronary events presenting as sudden death increases with age in both men and women. Relative weight is another important risk factor; the age-adjusted rate of sudden cardiac death for the upper weight tercile in the Framingham study was over 2 times higher for men and 3 times higher for women than the rate for the lower weight tercile. Most patients who die suddenly initially experience ventricular tachycardia that subsequently degenerates into ventricular fibrillation. Patients with a high risk of sudden cardiac death include: survivors of myocardial infarction with left ventricular dysfunction or complex ventricular ectopy, or both; survivors of out-of-hospital cardiac arrest, particularly when the event is not associated with an acute myocardial infarction; patients with recurrent ventricular tachycardia; and patients with dilated congestive cardiomyopathy, particularly when associated with ventricular ectopy. Reducing the risk of sudden death in these patients remains a major challenge.

First myocardial infarction: age and ejection fraction identify a low-risk group

This study examines patients with a first myocardial infarction (MI) (about 70% of the population, n = 2089), and identifies factors associated with 1-year cardiac mortality in patients discharged alive. With the use of multivarate analysis of variables observed at hospital discharge in patients with a first MI, age was the most important predictor, followed by left ventricular ejection fraction (LVEF) (determined in 56%) and other variables. Based on this finding, age subsets (less than or equal to 50, 51 to 70, greater than 70 years) were related to LVEF groups (less than or equal to 0.40, 0.41 to 0.50, greater than 0.50). Patients with a first MI who were less than 50 years of age with LVEF greater than 0.40 and patients between 51 and 70 years of age with LVEF greater than 0.50 had a very low risk for 1-year cardiac death, 1.2 +/- 1.1% (95% confidence interval). Such patients comprised 47% of individuals with a first MI having an LVEF determination. Mortality in the remaining patients less than 70 years was 7.4 +/- 3.5%. Mortality for patients greater than 70 years was high, 22.2 +/- 6.6%. Thus with LVEF as the only predischarge test, a sizable low risk group can be identified among patients with a first MI.

Prognosis of ventricular arrhythmias in relation to sudden cardiac death: therapeutic implications

The hypothesis that ventricular arrhythmias represent an independent predictor of sudden cardiac death was examined by analyzing the published data. The frequency and complexity of ventricular arrhythmias increase progressively both with age and severity of heart disease, but no age- or disease-related norms have been established for clinical guidance. Simple and complex arrhythmias, including short runs of ventricular tachycardia, do not increase risk of sudden cardiac death in subjects without heart disease or with heart disease and normal myocardial function. Progression of nonsustained into sustained ventricular tachycardia in such individuals is rare. Simple and complex ventricular arrhythmias are not strong independent predictors of sudden death in survivors of myocardial infarction. In these, the overall incidence of sudden cardiac death averages 3.5 to 5% during the first year, but is about 15 to 20% per year in patients with severely impaired ventricular function. The results of this survey suggest that in patients with well preserved ventricular function, prophylactic use of antiarrhythmic drugs is not indicated, and that treatment of asymptomatic or mildly symptomatic ventricular arrhythmias is not likely to reduce the incidence of sudden cardiac death.

Prognostic significance of ventricular ectopic activity in survivors of acute myocardial infarction

Twenty-four hour ambulatory electrocardiography was performed on 3,290 survivors of acute myocardial infarction participating in the Beta-Blocker Heart Attack Trial (BHAT). History of myocardial infarction before the qualifying event, congestive heart failure and age were independently associated with the frequency and complexity of ventricular premature beats. Of the 1,640 patients randomized to placebo therapy, 163 died (76 suffered sudden death) during a 25 month average follow-up period. Ventricular ectopic activity was an independent predictor of total mortality after taking into consideration 16 other prognostic factors describing past history, risk factors, physical examination and laboratory investigations. Seven categoric definitions of ventricular ectopic activity predicted mortality, with similar odds ratios ranging from 2.27 to 2.69. A reciprocal relation of the sensitivity and specificity of each definition in predicting mortality was observed. Three clinical criteria (ST depression, cardiomegaly and prior infarction) allowed stratification of patients into four subsets with respective mortality rates of 35.5% (three criteria present), 19.0% (two criteria), 11.5% (one criterion) and 4.7% (none). Presence of ventricular ectopic activity (greater than or equal to 10 ventricular premature beats/h or pairs, ventricular tachycardia or multiform complexes) was associated with higher mortality rates in all four risk strata. The relative risk was higher (3.86) in the lowest risk stratum (mortality 2.4% without and 9.1% with ventricular ectopic activity). Thus, in survivors of acute myocardial infarction, ventricular ectopic activity was more pronounced in patients with prior myocardial infarction and congestive heart failure. It predicted mortality independently of other factors. Although mortality ratios were similar for all seven arrhythmia definitions, a reciprocal relation between sensitivity and specificity of the definitions in predicting mortality existed; ventricular ectopic activity was associated with increased mortality in all risk strata, but with a higher risk ratio in the numerically larger, low risk subset.

The murmur of papillary muscle dysfunction in acute myocardial infarction: clinical features and prognostic implications

The systolic murmur of papillary muscle dysfunction is a well-recognized feature of acute myocardial infarction (AMI), but no large prospective studies have determined its incidence, associated variables, and prognostic implications. Of 1653 patients who entered our data base with MI, 283 (17%) were classified as having a systolic murmur suggesting mitral regurgitation. At hospital discharge, there was a 5% incidence. There was a higher incidence of systolic murmur in non-Q wave AMI than in inferior or anterior Q wave MI (24% vs 13% and 15%, p less than 0.001). Advanced age, previous MI, and heart failure were all associated with systolic murmur (p less than 0.01). Persistent pain in the coronary care unit occurred more often in those with systolic murmur (45% vs 26%, p less than 0.0001). Systolic murmur was associated with an S3 and bibasilar rales (p less than 0.001) in the hospital; however, it was inversely related to peak creatine kinase and unrelated to heart failure or ejection fraction at discharge. Univariate predictors of mortality associated with systolic murmur included complex premature ventricular contractions at discharge and a non-Q wave location. Patients with systolic murmur had higher hospital and 1-year mortalities than those without systolic murmurs (p less than 0.01). When systolic murmur was present during hospitalization, the average time to reinfarction was 2.5 times earlier than when no systolic murmur was present (84 vs 214 days, p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Non-Q-wave myocardial infarction

The rationale for introducing the term "non-Q-wave myocardial infarction" is identified. The incidence, pathology, pathogenesis, and diagnostic criteria for this condition, previously identified as nontransmural or subendocardial infarction, are reviewed. In reviewing the diagnostic criteria, the various noninvasive techniques that may be applied are discussed. The clinical course, prognosis, and management are discussed under the headings of early postinfarction period, late clinical course, predischarge evaluation, and long-term care. The issues of the management of infarct extension and acute interventional therapy are raised and reviewed. Suggestions regarding specific aspects of therapy in non-Q-wave myocardial infarction are included in the summary.