Role of beta-adrenergic blockers after percutaneous transluminal coronary angioplasty

Beta-blocker use in the emergency department in patients with acute myocardial infarction undergoing primary angioplasty

Our objectives were to evaluate the frequency of beta-blocker administration in the setting of acute myocardial infarction (AMI) where angioplasty is the primary treatment, and to investigate emergency physician's (EPs) attitudes toward beta-blockers. We performed a retrospective chart review of all patients who presented with symptoms and electrocardiogram (EKG) criteria consistent with AMI in the defined study period. Charts were reviewed for beta-blocker administration and other treatments. A survey was subsequently distributed to all EPs to determine self-reported reasons for withholding beta-blockers. There were 91 patients identified. Of those who did not have contraindications, 99% (89/90) received aspirin, 97% (88/91) received heparin, 94% (84/89) received nitrates, but only 28% (19/68) received beta-blockers. Ninety-six percent of beta-blocker-eligible patients received them as inpatients. Eighty-six percent (44/52) of EPs completed the survey. Physicians felt strongly about avoiding beta-blockers in patients with asthma exacerbation, severe congestive heart failure, and high degree AV block. Bradycardia was the most frequent reason for withholding beta-blockers. In this series of patients presenting with AMI, beta-blockers were greatly underutilized. The self-reported reasons of EPs for withholding beta-blocker therapy did not explain why 72% (49/68) of patients without contraindications did not receive beta-blockers.

Beta-blockers reduce the incidence of clinical restenosis: prospective study of 4840 patients undergoing percutaneous coronary revascularization

BACKGROUND

Restenosis after percutaneous transluminal coronary intervention (PCI) remains a serious complication in the treatment of coronary artery disease. Although beta-adrenergic receptor blockers (BBs) effectively reduce many cardiac events, no large prospective studies have examined the association of BBs with restenosis.

METHODS

We prospectively evaluated the association of BBs (prescribed at hospital discharge) with clinical restenosis in 4840 patients who underwent stent placement (60%), balloon angioplasty (32%), or rotational atherectomy (8%). Clinical restenosis was defined as repeat target lesion revascularization or coronary artery bypass grafting within 6 months of PCI. Other end points included 9-month clinical restenosis, repeat target lesion PCI (only), long-term (5-year) target lesion repeat-PCI, and major adverse cardiac events (MACE). Multivariable regression adjusted the effect of BBs on clinical restenosis for 15 covariables.

RESULTS

The average patient age was 63 years, 75% were men, and 37% received a BB prescription. The incidence of clinical restenosis was 12% overall and was lower among those prescribed a BB (10.0% for BB, 13.5% for none, adjusted odds ratio [OR] 0.76, P =.004). Other predictors of decreased restenosis included stent use, age, and smoking; predictors of increased restenosis included diabetes, atherectomy, and number of treated vessels. BBs also reduced 9-month clinical restenosis (10.3% vs 13.5%, OR 0.75, P =.004), MACE (16.5% vs 20.9%, OR 0.75, P <.001), 6-month target lesion restenosis (7.8% vs 10.2%, OR 0.75, P =.006), and 5-year target lesion restenosis (12.0% vs 14.0%, OR 0.83, P =.046).

CONCLUSIONS

beta-Adrenergic receptor blockers prescribed after PCI reduced the risk of clinical restenosis, target lesion restenosis, and MACE in this cohort of 4840 patients. The mechanism by which beta-blockers conferred a protective effect against restenosis remains to be determined.

Effects of intensified lifestyle modification on the need for further revascularization after coronary angioplasty

BACKGROUND

In patients with coronary artery disease (CAD), a rate of restenosis as high as 50% is observed after percutaneous transluminal coronary angioplasty (PTCA). Frequently, this results in further revascularization procedures. Lifestyle intervention has been shown to slow the progression of CAD and to reduce cardiovascular events after myocardial infarction. However, no information exists whether such treatment influences the rate of restenosis in patients with CAD. The present study was performed to investigate the effects of an intensified lifestyle intervention on the need for further revascularization procedures in patients with established CAD after successful PTCA.

DESIGN

A total of 60 patients were included and randomized to either conventional treatment by cardiologists and general practitioners or additional intensified lifestyle intervention in a diabetes and metabolism outpatient clinic for 12 months. The mean observation time after successful PTCA was 26 months. The primary outcome variable was the need for further revascularization procedures because of clinical restenosis. Secondary outcome variables were lifestyle-related measures.

RESULTS

Intervention resulted in a reduction in body weight and blood pressure, and in increased physical activity. Furthermore, nutritional habits were changed towards less fat intake, and body composition changed towards a higher proportion of fat-free mass. The need for further revascularization procedures was reduced from a total of 14 out of 32 in the conventionally treated group to 3 out of 28 in the intervention group. This resulted in an event-free survival probability of 0.89 in the intervention group and 0.57 in the control group (P = 0.0055, log rank) with a resulting relative risk of 0.26 (95% CI 0.09-0.74).

CONCLUSION

In conclusion, our data strongly suggest that intensified lifestyle modification is able to reduce the need for further revascularization procedures after PTCA in patients with CAD.

Effects of stent design and serum cholesterol level on the restenosis rate in atherosclerotic rabbits

We investigated the effect of serum cholesterol level and stent design on the restenosis rate within the stent after balloon angioplasty and stent implantation using atherosclerotic rabbits. Two types of nickel/titanium stents with gaps (open stent) and without gaps (closed stent) between the wire coils were implanted into the aorta of the rabbits 10 weeks after atherosclerosis had been induced using a standard high cholesterol diet and balloon abrasion. Each rabbit had an open stent and a closed stent implanted into the infrarenal abdominal aorta. Between these two stents a control segment of the aorta was treated with angioplasty alone. The animals were divided into two groups according to the diet protocol as follows: in group I (n = 9) a high cholesterol diet was stopped after stent implantation; in group II (n = 10) a high cholesterol diet was maintained after stent implantation. Digital subtraction angiograms were obtained every 4 weeks for up to 24 weeks and the narrowest diameter of the arterial segments within each stent and in the segment between stents was measured. The diameter narrowing within the closed stent was greater in the high cholesterol group compared with the low cholesterol group: 12 weeks (2.57 +/- 0.09 mm in group I vs 2.14 +/- 0.15 mm in group II, mean +/- S.E., p < 0.05); 16 weeks (2.55 +/- 0.09 mm vs 2.14 +/- 0.12 mm, p < 0.05); 20 weeks (2.59 +/- 0.06 mm vs 1.98 +/- 0.12 mm, p < 0.01); and 24 weeks (2.45 +/- 0.11 mm vs 2.01 +/- 0.11 mm, p < 0.05). No significant differences in the narrowest diameter of the arterial segments were observed between high and low cholesterol groups in the angioplasty alone areas or within the open stents. There was a significant difference in the narrowest diameter between stents with versus those without gaps (at 12, 16, and 20 weeks poststenting in group I and at 4, 8, 12, 16, 20, and 24 weeks in group II). Thus the stent with the least metal is correlated with less stenosis and intimal hyperplasia. From these data we conclude that both stent design and serum cholesterol are important factors for restenosis after stent implantation.

Restenosis after coronary angioplasty

Coronary angioplasty is used to treat coronary disease in many patients. Indications for angioplasty have expanded since it was first performed, mainly as a result of improvement in equipment and techniques. One problem with coronary angioplasty is the phenomenon of renarrowing of the treated coronary lesion, a process called restenosis. The events that constitute restenosis appear to be a universal response to the arterial wall injury of angioplasty. They are currently characterized as follows: platelet adhesion and aggregation on the damaged endothelium and within deep splits into the tunica media; release of platelet-derived growth factors; inflammation of the mechanically injured medial zone; transformation of smooth muscle cells of the tunica media after their activation by several of the growth-promoting substances; migration and proliferation of transformed smooth muscle cells, with secretion of copious amounts of extracellular matrix material; and, finally, termination of the growth process with regrowth of endothelium over the injured area. A decade of research work has helped identify clinical correlates of restenosis after coronary angioplasty procedures. This work is hindered by lack of a uniform angiographic definition of restenosis. In addition, much of the information has come from small studies, with incomplete follow-up and retrospective orientation. Nevertheless, some data are available. Patient-related correlates include male gender, unstable angina, diabetes, and continued smoking after angioplasty. Lesion-related correlates include multilesional and multivessel procedures, higher postangioplasty residual stenosis, proximal vessel location, location in the left anterior descending artery, location in a vein graft, long lesions, and total occlusions. The only consistent procedure-related correlate has been incorrect sizing of the angioplasty balloon to the treated artery. For the purposes of individual patient care, clinical correlates are not helpful. No group of variables has been found to be associated with complete freedom from restenosis, and no group is completely predictive of restenosis. All patients undergoing angioplasty procedures require some follow-up through subsequent months and years. Symptom status and the results of noninvasive studies have been investigated for purposes of follow-up. Symptoms are virtually useless by themselves for predicting restenosis or its absence. When symptom status is combined with exercise thallium 201 scintigraphy performed 4 to 6 months after an angioplasty procedure, the two factors are less than ideal but have a negative predictive value of more than 90%. This means that more than 90% of patients who have neither symptoms nor evidence of ischemia by thallium 201 scintigraphy will not have angiographic restenosis.(ABSTRACT TRUNCATED AT 400 WORDS)

Restenosis after coronary angioplasty

Coronary angioplasty is used to treat coronary atherosclerotic disease in many patients. One problem with coronary angioplasty is the phenomenon of restenosis. Restenosis appears to be a universal response to arterial wall injury. The biological events that underlie restenosis are characterized by: platelet adhesion and aggregation at sites of damaged endothelium, and within dissections into the medial layers, release of platelet derived growth-promoting substances, inflammation of the injured medial zone, transformation, migration, and proliferation of smooth muscle cells of the media following their activation by growth-promoting substances, secretion of copious amounts of extracellular matrix material, and finally, termination of the growth process following regrowth of endothelium over the damaged area. More than a decade of research work has helped identify clinical correlates of restenosis after coronary angioplasty. Patient-related correlates include male gender, unstable angina, diabetes, and continued smoking after angioplasty. Lesion-related correlates include multilesion and multivessel procedures, higher post-angioplasty residual stenosis, proximal vessel location, location in the left anterior descending coronary artery, location in a vein graft, long lesions, and total occlusions. However, for the purposes of individual patient care, clinical correlates are not particularly helpful. No group of variables has predicted complete freedom from restenosis, and conversely no group of variables has reliably indicated its presence. All patients undergoing angioplasty will require some form of follow-up evaluation. Symptom status by itself has not been found to be useful for predicting restenosis. However, when symptom status is combined with exercise thallium-201 scintigraphy, performed 4-6 months after angioplasty, it is less than ideal, but has a negative predictive value of over 90%. This means that over 90% of patients who are asymptomatic and have no evidence of ischemia by thallium-201 scintigraphy, will not have angiographic restenosis. Numerous clinical trials have been performed in order to reduce or prevent restenosis. Almost all have been disappointing, while a few have been encouraging. Studies of antiplatelet agents such as aspirin, dipyridamole (Boehringer Ingelheim Pharmaceuticals Inc., Ridgefield, CT, USA), and Ticlopidine (Syntex, Humgcao, Puerto Rico) have not shown efficacy, yet studies of an inhibitor of platelet-derived growth factor have been provocatively encouraging. No reduction in restenosis rates was found with the anticoagulants Coumadin (Du Pont Pharmaceuticals, Wilmington, DE, USA) and Heparin (Wyeth-Ayerst, Philadelphia, PA, USA). Fish oils (omega fatty acids) have been found in several clinical trials to provide modest, but encouraging, reductions in restenosis, but await further confirmation.(ABSTRACT TRUNCATED AT 400 WORDS)