Intracoronary radiation with a 32P source wire

The Proliferation REduction with Vascular ENergy Trial (PREVENT) is a prospective randomized study of the safety and efficacy of intracoronary brachytherapy to reduce restenosis. A beta-emitter, 32P, is embedded on a wire tip and delivered to the target site through a centering catheter immediately following a coronary intervention. The radiation doses are 16, 20, and 24 Gy measured at 1 mm within the vessel wall. Follow-up includes an angiogram and IVUS at 6 months. Phase I of this trial has been completed with results expected in early 1999.

Angiotensin-I converting enzyme genotype DD is a risk factor for coronary artery disease

BACKGROUND

Coronary artery disease (CAD) is a polygenic disease whose phenotypic manifestation is due to interaction of a number of environmental factors with an underlying genetic background. A number of genes, including the angiotensin-I converting enzyme (ACE) gene, have been implicated in the pathogenesis of CAD. ACE can affect oxidation of LDL, endothelial cell function, and smooth muscle cell migration and proliferation: all important components of atherosclerosis. A variant of ACE gene, genotype DD is associated with a higher plasma level of ACE and an increased risk of myocardial infarction, and cardiomyopathies. In this study, we sought to determine the distribution of ACE genotypes and the frequency of allele D in patients with CAD undergoing coronary angioplasty.

METHODS

DNA from 182 white patients undergoing coronary angioplasty and 338 apparently healthy white individuals was amplified by polymerase chain reaction (PCR) in the region of the polymorphism using the previously published protocol.

RESULTS

PCR amplification of alleles I and D resulted in 490 bp and 190 bp products, respectively. ACE genotype DD was present in 47% of patients with CAD as compared to 30% in the general population (p = 0.0002, Odds ratio 2.7). The frequency of allele D was 0.68 in patients with CAD and 0.55 in general population, respectively (p < 0.0001). Genotype DD was associated with CAD only in males (54% vs. 30%, p = 0.0001, Odds ratio 2.0), but not in female patients. There was no association between the frequency of ACE genotype DD and the prior history of myocardial infarction, or the extent of CAD. The frequency of ACE genotype DD was the highest among patients with restenosis following angioplasty (55%), however, the difference was not significantly changed as compared to those without restenosis (40%).

CONCLUSIONS

ACE genotype DD is more common in patients with CAD as compared to the general population, indicating that genotype DD is a genetic risk factor for CAD.

One-year results of the Thrombolysis in Myocardial Infarction investigation (TIMI) Phase II Trial

BACKGROUND

The Thrombolysis in Myocardial Infarction (TIMI) Phase II Trial randomized 3,339 patients to either an invasive (INV, n = 1,681) or a conservative (CON, n = 1,658) strategy after intravenous recombinant tissue-type plasminogen activator (rt-PA) for acute myocardial infarction.

METHODS AND RESULTS

The patients assigned to the INV strategy routinely underwent cardiac catheterization, and when anatomically appropriate, percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass grafting 18-48 hours after infarction. CON patients had these procedures only in response to the occurrence of spontaneous or provoked ischemia. One-year follow-up data are available in 3,316 patients (99.3%). The primary trial end point, death and nonfatal reinfarction, occurred in 14.7% of INV patients and in 15.2% of CON patients (p = NS). When analyzed individually, there was no difference (p = NS) in death (INV, 6.9%; CON, 7.4%) or recurrent infarction (INV, 9.4%; CON, 9.8%) between the two groups. Anginal status at 1 year was also similar. Cardiac catheterization and PTCA were performed more often in INV (98.0% and 61.2%, respectively) compared with CON (45.2% and 20.5%, respectively) patients. At 1 year, the cumulative number of patients who underwent coronary bypass surgery (INV, 17.5%; CON, 17.3%) was similar in the two groups.

CONCLUSIONS

The INV and CON strategies resulted in similar favorable outcomes at 1 year of follow-up. In particular, the rates of mortality and reinfarction were not different and were impressively low in both groups. One possible advantage of the INV strategy was detected in subgroup analyses. In patients with a history of myocardial infarction, the data are suggestive that 1-year mortality was lower in INV patients (10.3%) than in CON patients (17.0%) (p = 0.03).

Complex ventricular arrhythmias associated with the mitral valve prolapse syndrome. Effectiveness of moricizine (Ethmozine) in patients resistant to conventional antiarrhythmics

On the basis of epidemiologic studies, more than 10 million Americans have echocardiographic evidence of mitral valve prolapse. Although ventricular arrhythmias occur frequently (over 50 percent of patients with mitral valve prolapse), they rarely result in sustained ventricular tachycardia or sudden cardiac death. However, a common problem in clinical practice is a patient with mitral valve prolapse and symptomatic complex ventricular arrhythmias refractory or intolerant to both beta blockers and conventional type I antiarrhythmics. These drugs are known to have frequent side effects, toxicity, and proarrhythmic effects. In 17 patients with mitral valve prolapse who presented with symptomatic complex ventricular arrhythmias and who were unresponsive to an average of the three conventional agents, moricizine (Ethmozine) was effective in suppressing 90 percent of ventricular premature depolarizations, 99 percent of nonsustained runs of ventricular tachycardia, as well as all sustained runs of ventricular tachycardia, resulting in abolition of palpitations, dizziness, and syncopal episodes. Its efficacy as well as its low frequency of minor side effects makes it ideal for future consideration in the population with mitral valve prolapse, who are frequently young and may therefore require therapy for many years.

The effect of nifedipine on serum digoxin concentrations in patients

Drug interactions with digoxin are being increasingly recognized. Some calcium antagonists have been shown to alter digoxin kinetics and changes in digoxin dosage have been recommended. To determine whether nifedipine affects serum digoxin concentrations in patients during combined drug administration, serum digoxin concentrations were determined before and during concomitant drug administration in 14 cardiac patients. The mean (+/- SD) digoxin concentration was 0.92 +/- 0.5 ng/ml before and 0.96 +/- 0.5 ng/ml after 4 days of nifedipine therapy in eight inpatients. For the group of 14 patients, the mean level was 0.78 +/- 0.4 ng/ml before nifedipine and 0.8 +/- 0.4 ng/ml after 1 week of combined drug administration, and 0.84 +/- 0.5 ng/ml after 2 weeks of combined drug administration. These data suggest that nifedipine does not significantly alter serum digoxin concentrations in cardiac patients receiving combined digoxin and nifedipine in the clinical setting.