Verapamil treatment after coronary angioplasty in patients at high risk of recurrent stenosis

Calcium channel regulation in vascular smooth muscle cells: synergistic effects of statins and calcium channel blockers

In the Anglo-Scandinavian Cardiac Outcomes Trial-Lipid Lowering Arm (ASCOT-LLA) we have reported a positive interaction between atorvastatin and amlodipine-based antihypertensive strategy in terms of the prevention of coronary events. In cellular and molecular studies on human vascular smooth muscle cells (VSMC) we have reported that transformation from a differentiated to a synthetic or dedifferentiated phenotype is associated with loss of function of L-type calcium channels and hence loss of potential responsiveness to calcium channel blockers (CCB). Statins directly inhibit cell cycle progression and dedifferentiation of VSMC due to their ability to inhibit the synthesis of isoprenoid cholesterol intermediates. We hypothesize that statins promote a more differentiated VSMC phenotype that results in upregulation of L-type calcium channels and restoration of a CCB-sensitive calcium influx pathway in VSMC, favourably affecting the balance that exists between VSMC proliferation, apoptosis and matrix metalloproteinase production with an associated increase in stability of atheromatous plaques.

Verapamil use in patients with cardiovascular disease: an overview of randomized trials

BACKGROUND

Several reports have questioned the lack of safety data on calcium antagonists as a drug class. Because this drug class is heterogeneous, unique features of certain calcium antagonists may set them apart in terms of safety and efficacy.

HYPOTHESIS

With in excess of 7,000 person-years of observation from randomized clinical trials, verapamil was selected to evaluate whether there was evidence of harm in patients with cardiovascular disease.

METHODS

MEDLINE search of English-language articles, Science Citation Index, Current Contents, manual review of cited references, pharmaceutical files, and investigator correspondence was performed. Independent review of 66 articles identified 14 randomized, parallel-group studies for inclusion. Independent, duplicate assessments were made of patient outcomes and trial characteristics (including study design, treatment dosage and schedule, duration of treatment, inclusion criteria, and sample size). Standard meta-analytic techniques were employed for analysis and interpretation of results.

RESULTS

Based on over 4,000 person-years of observation, patients with acute myocardial infarction (MI) treated with verapamil had a decreased risk of nonfatal reinfarction compared with placebo (relative risk 0.79; 2-sided 95% confidence interval 0.65.0.97; p = 0.024). Verapamil had no significant effect on overall mortality compared with placebo (relative risk ranged from 0.93; 2-sided 95% confidence interval 0.78, 1.10; p = 0.40 to 0.86; 2-sided 95% confidence interval 0.71, 1.04; p = 0.13) depending on rules used to include or exclude patients from the pooling process. For the combined outcome of death or reinfarction, verapamil use was associated with a decreased risk compared with placebo (relative risk 0.82; 2-sided 95% confidence interval 0.70, 0.97; p = 0.016). In patients with angina involving a wide spectrum of disease severity, data were limited to 2,900 person-years of observation, and verapamil use did not appear to be associated with an apparent effect on mortality or MI. Data available from randomized studies of verapamil in patients with hypertension were too limited to reach conclusions (50 person-years of observation, with no deaths or MIs reported). Subgroups of hypertensive patients in two of the largest post-MI studies and the largest angina study, involving over 600 patients, yielded little useful added information.

CONCLUSIONS

In patients with MI, the risks of both nonfatal reinfarction and the combined outcome of death or nonfatal MI were reduced over intermediate-term follow-up among patients treated with verapamil compared with controls (p = 0.024 and p = 0.016, respectively). In patients with angina, no evidence for harm was noted, but in hypertension the data were too limited to draw conclusions. These findings support the need to distinguish among different calcium antagonist compounds and to emphasize the need for more data in patients with hypertension.

Evaluation of the effect of oral verapamil on clinical outcome and angiographic restenosis after percutaneous coronary intervention

OBJECTIVES

We investigated the effect of oral verapamil on clinical outcome and angiographic restenosis after percutaneous coronary intervention (PCI).

BACKGROUND

Thus far, there is no established systemic pharmacologic approach for the prevention of restenosis after PCIs. Five small studies reported encouraging results for calcium channel blockers.

METHODS

Our randomized double-blind trial included 700 consecutive patients with successful PCI of a native coronary artery. Patients received the calcium channel blocker verapamil, 240 mg twice daily for six months, or placebo. Primary clinical end point was the composite rate of death, myocardial infarction, and target vessel revascularization (TVR) during one-year follow-up; the angiographic end point was late lumen loss at the six-month follow-up angiography.

RESULTS

We obtained complete clinical follow-up in 95% of the patients, and scheduled angiography was performed in 94%. The proportion of patients treated with stents was 83%. The primary clinical end point was reached in 67 (19.3%) patients on verapamil and in 103 (29.3%) patients on placebo (relative risk [RR] 0.66 [95% confidence interval (CI) 0.48 to 0.89]; p = 0.002). This difference between the groups was driven by TVR (17.5% with verapamil vs. 26.2% with placebo; RR 0.67 [95% CI 0.49 to 0.93]; p = 0.006). Late lumen loss was 0.74 +/- 0.70 mm with verapamil and 0.81 +/- 0.75 mm with placebo (p = 0.11). Compared with placebo, verapamil reduced the rate of restenosis > or =75% (7.8% vs. 13.7%; RR 0.57 [95% CI 0.35 to 0.92]; p = 0.014).

CONCLUSIONS

Verapamil compared with placebo improves long-term clinical outcome after PCI of native coronary arteries by reducing the need for TVR. This was caused by a reduction in the rate of high-grade restenosis.

Periprocedural routines of coronary angioplasty--extreme diversity with unrevealed consequences

Our objective was to evaluate the current trends of coronary angioplasty periprocedural care in the state of Israel. PTCA technology has undergone through some major developments and refinements, which have yielded new algorithms and routines. With this shift of paradigms, some of the periprocedural routines (these include medications and dosing before, during and after the procedure, as well as the handling of anti-coagulation, femoral sheath removal and the extent of patient monitoring post-PTCA) have been partially re-established. In order to assess trends in periprocedural care, we elected to analyze the current state of practice in the state of Israel. A questionnaire was sent to every cardiac catheterization laboratory in Israel that performs PTCA. An authorized senior cardiologist representing the laboratory submitted the information required for our survey. A nurse-to-nurse telephone questionnaire was conducted simultaneously to cross-examine the validity of the data. All centers submitted results. The average heparin dose for PTCA varied between 5000 and 15 000 units, ACT was monitored routinely by some and not at all by others, post-PTCA heparin administration was routinely administered by some institutions and not by others, and the mean femoral sheath dwell time ranged from 4 to 18 h. Post-PTCA cardiac monitoring varied from 6 to more than 24 h. Some institutions prescribed to all patients nitrates, calcium channel blockers and low-molecular-weight heparin, while others did not. We conclude that there is profound variability in the periprocedural routines that may translate into a significant cost increase, patient discomfort, a prolonged monitoring and hospital stay, and potential patient morbidity. We suggest that these routines should be critically evaluated, and that if they do not contribute to the procedural success and patient well-being they should be abandoned.

Critical assessment of the outcome of infrainguinal vein bypass

OBJECTIVE

To perform a more critical assessment of infrainguinal vein bypass.

SUMMARY BACKGROUND DATA

Graft patency may give an unrealistic impression of the outcome of bypass surgery.

METHODS

During a 6-year period, 236 patients undergoing primary vein grafts were entered into the study. An ideal outcome required the patient to have survived 12 months with a patent graft on duplex scanning, no perioperative complication, and no further related open or endovascular surgery or admission.

RESULTS

At 12 months, the secondary graft patency rate was 82%; however, only 22% of patients had an ideal outcome. At 1 year, 44 (19%) patients died, 93 (39%) required further ipsilateral and 39 (17%) contralateral intervention, and a total of 108 (46%) were readmitted. An ideal outcome was more likely in patients receiving calcium channel blockers, principally because of improved primary patency, and less likely in those with cardiac failure requiring furosemide, principally because of worse survival in these patients.

CONCLUSIONS

Few patients achieve an ideal result after infrainguinal vein bypass. Outcome may be improved by the use of calcium channel blockers. Careful consideration is required before performing revascularization in patients with cardiac failure.

Usefulness of Nisoldipine for prevention of restenosis after percutaneous transluminal coronary angioplasty (results of the NICOLE study). NIsoldipine in COronary artery disease in LEuven

The NIsoldipine in COronary artery disease in LEuven (NICOLE) study investigates (1) whether nisoldipine, a dihydropyridine calcium antagonist, reduces the progression of minor coronary arterial lesions in the long term, and (2) whether it reduces the restenosis rate after successful percutaneous transluminal coronary angioplasty (PTCA). The NICOLE study is a single-center, randomized, double-blind trial in 826 patients, who underwent a successful PTCA. Nisoldipine 40 mg coat-core or placebo was started the morning after the procedure and continued for 3 years. All coronary arterial segments were measured on preprocedural angiogram and on the second follow-up angiogram at 3 years. On the first follow-up angiogram at 6 months only the dilated segments were measured. Although the study is still ongoing until the primary end point is reached, we report in this study the angiographic restenosis data as well as the clinical events observed at 6-month follow-up. The per-protocol population consisted of 646 patients. Restenosis, defined as a > or =50% loss of the initial gain (National Heart, Lung, and Blood Institute criterion IV) occurred in 49% and 55% of the 308 nisoldipine-treated and the 338 placebo-treated patients, respectively (p = NS). At follow-up, the rates of death and myocardial infarction were low and similar in both groups, but in the nisoldipine group, less patients required early coronary angiography (18% vs 26%, p = 0.006) and subsequent revascularization procedures (32% vs 41%, p = 0.057). Thus, nisoldipine did not significantly reduce the angiographic restenosis rate after PTCA, but reduced the number of repeat revascularization procedures, which may be due to its antianginal action.

Current status of safety and efficacy of calcium channel blockers in cardiovascular diseases: a critical analysis based on 100 studies

Recently, serious concerns have been expressed about the long-term safety of the calcium channel blockers (CCBs) as a group. Safety and efficacy are, however, ultimately linked to each other; therefore both must be evaluated especially in the therapy of angina and hypertension, the main clinical indications for CCBs. The structural, functional, and pharmacokinetic heterogeneity of CCBs means that the efficacy and dangers of one subclass, such as the short-acting dihydropyridines (DHPs), in one situation, such as unstable angina, do not necessarily apply in other clinical situations. One hundred studies are reviewed according to their methods of data collection: case series, case control, cohort, randomized controlled trials (RCTs), and meta-analyses. Large, well-designed RCTs and the meta-analyses based on these trials remain the gold standard. Observational studies, though potentially less reliable sources of information because of selection bias, may nevertheless produce hypotheses that must then be tested in RCTs. Regarding safety, both observational studies and RCTs suggest that adverse effects of CCBs may be linked to short-acting agents, specifically short-acting nifedipine. Two good studies favor the safety of verapamil, even in short-acting form. Incomplete but increasing overall evidence favors the safety of longer-acting DHPs. Heart failure remains a class contraindication to the use of all CCBs, with some exceptions. Regarding efficacy, there are positive results of RCTs with CCBs in 2 specific clinical situations, namely, verapamil in postinfarct protection in the absence of pre-existing heart failure, and 2 outcome studies on hypertension with longer acting DHPs. These results cannot automatically be applied to other clinical situations and to other CCBs. For example, there is no evidence for the safety or efficacy of DHPs used without beta blockers in postinfarct patients. In diabetic hypertensives, 2 relatively large RCTs show that the blood pressure can be reduced by DHP-based therapy in diabetics, with a reduction in hard end points. To achieve current blood pressure goals, combination therapy is almost always necessary, and in diabetics there is strong evidence that 1 essential component should be an angiotensin converting enzyme inhibitor. The future aim with CCBs must be to obtain a large database gathered from RCTs, which will give the same certainty about efficacy and safety that already holds for use of the diuretics in hypertension, beta-blockers in postmyocardial infarction patients, and the angiotensin converting enzyme inhibitors in heart failure.

Restenosis and clinical outcome in patients treated with amlodipine after angioplasty: results from the Coronary AngioPlasty Amlodipine REStenosis Study (CAPARES)

OBJECTIVES

Our intent was to investigate the effect of the dihydropyridine calcium channel blocker amlodipine on restenosis and clinical outcome in patients undergoing percutaneous transluminal coronary angioplasty (PTCA).

BACKGROUND

Amlodipine has sustained vasodilatory effects and relieves coronary spasm, which may reduce luminal loss and clinical complications after PTCA.

METHODS

In a prospective, double-blind design, 635 patients were randomized to 10 mg of amlodipine or placebo. Pretreatment with the study drug started two weeks before PTCA and continued until four months after PTCA. The primary angiographic end point was loss in minimal lumen diameter (MLD) from post-PTCA to follow-up, as assessed by quantitative coronary angiography (QCA). Clinical end points were death, myocardial infarction, coronary artery bypass graft surgery and repeat PTCA (major adverse clinical events).

RESULTS

Angioplasty was performed in 585 patients (92.1%); 91 patients (15.6%) had coronary stents implanted. Follow-up angiography suitable for QCA analysis was done in 236 patients in the amlodipine group and 215 patients in the placebo group (per-protocol group). The mean loss in MLD was 0.30 +/- 0.45 mm in the amlodipine group versus 0.29 +/- 0.49 mm in the placebo group (p = 0.84). The need for repeat PTCA was significantly lower in the amlodipine versus the placebo group (10 [3.1%] vs. 23 patients [7.3%], p = 0.02, relative risk ratio [RR]: 0.45, 95% confidence interval [CI]: 0.22 to 0.91), and the composite incidence of clinical events (30 [9.4%] vs. 46 patients (14.5%), p = 0.049, RR: 0.65, CI: 0.43 to 0.99) within the four months follow-up period (intention-to-treat analysis).

CONCLUSIONS

Amlodipine therapy starting two weeks before PTCA did not reduce luminal loss, but the incidence of repeat PTCA and the composite major adverse clinical events were significantly reduced during the four-month follow-up period after PTCA with amlodipine as compared with placebo.

The Verapamil in Hypertension and Atherosclerosis Study (VHAS): results of long-term randomized treatment with either verapamil or chlorthalidone on carotid intima-media thickness

BACKGROUND

It is unclear whether the carotid intima-media thickness can be influenced by antihypertensive treatment and whether some antihypertensive agents, such as calcium antagonists, may have a greater effect on this parameter than others, such as diuretics. The present paper reports the principal results of the ultrasound substudy of the randomized, prospective, controlled, Verapamil in Hypertension and Atherosclerosis Study (VHAS).

DESIGN AND METHODS

In 498 hypertensive patients in eight Italian centres, randomized to either verapamil (240 mg once a day) or chlorthalidone (25 mg once a day), a B-mode ultrasound scan was performed according to a standardized procedure at baseline and after 3, 12, 24, 36 and 48 months of treatment. The maximum intima-media thicknesses of the far walls of common, bifurcation and internal carotid arteries were measured bilaterally, and the following indices calculated: the mean thickness at the six measured sites, the mean thickness at the common and bifurcation sites and the single maximum thickness. The primary endpoint for treatment efficacy was the slope of the change over 4 years (rate of change, mm/year), corrected by using the initial mean over the six sites (baseline + 3 months) as a covariate (mm/year per mm). The patients were also classified into three strata according to their baseline single maximum thickness: those with normal carotid arteries (single maximum ( 1 mm), those with thickened carotid arteries (single maximum > 1 and < or = 1.5 mm and those with carotid plaques (single maximum > 1.5 mm).

RESULTS

Among the 456 patients with satisfactory baseline ultrasound readings, 33% were classified with normal carotid arteries, 27% with thickened carotid arteries and 40% with plaques. In the intention-to-treat population (377 patients with ultrasound measurements taken on at least three different occasions over a period of at least 2 years), the rate of change in the mean thickness at the six sites measured was rather small (0.015 mm/year), but significantly (P < 0.05) smaller in patients with plaques (0.003 mm/year) than in patients with thickened or with normal carotids (0.023 and 0.025 mm/year, respectively). When related to initial values, the rate of change in the mean thickness at the six sites had a negative slope (-0.059 mm/year per mm, P < 0.01). Although rates of change in the carotid intima-media thickness in unstratified patients were not different in those treated with verapamil or with chlorthalidone, when changes in the mean thickness of six sites were related to the initial value, the slope of this relationship was significantly different in the two treatment groups (verapamil -0.082 versus chlorthalidone -0.037 mm/year per mm, P < 0.02). The blood pressure-lowering effect of the two randomized treatments was similar. Taking fatal and nonfatal, major and minor cardiovascular events together, there were 19 events in the verapamil group and 35 in the chlorthalidone group, with a significantly (P < 0.01) greater incidence in patients with plaques, and among patients with plaques in those who were randomized to chlorthalidone (P < 0.05).

CONCLUSIONS

In accord with evidence from animal models of atherosclerosis, the calcium antagonist verapamil was more effective than the diuretic chlorthalidone in promoting regression of thicker carotid lesions. Changes in the carotid intima-media thickness were small in both groups, and the differences between the changes under the two treatments were consequently small, but the observation that these small differences in carotid wall changes were paralleled by differences in the incidence of cardiovascular events (better intima-media thickness regression with verapamil paralleled by a lower cardiovascular event rate) suggests that even small effects on carotid plaques may have clinical and prognostic relevance.

Pharmacological approaches to the prevention of restenosis after coronary angioplasty

Restenosis in the months following a successful percutaneous transluminal coronary angioplasty (PTCA) remains the main limitation to this technique for myocardial revascularisation. Despite intensive investigation in this area, no pharmacological therapy has yet been found to be useful in preventing restenosis after conventional balloon angioplasty. The occurrence of restenosis, which is now known to be caused by both vessel remodelling and neointimal hyperplasia, might be reduced in the future by a combined mechanical and pharmacological approach. Although systemic administration of 'antirestenosis' drugs has not yet been tested to prevent restenosis after coronary stenting, it is very likely that pharmacological inhibition of neointimal hyperplasia within coronary stents will take advantage of local delivery techniques. In addition to local drug delivery catheters that are available, the stent itself may be coated with polymers and serve as a platform for drug delivery. The continued attractiveness of PTCA, as an alternative to medical treatment or bypass surgery for patients with coronary artery disease, will depend upon our ability to control the restenotic process.

Effect of diltiazem and verapamil on endothelin release by cultured human coronary smooth-muscle cells and endothelial cells

Recent data suggest that endothelin (ET) production is enhanced in coronary atherosclerotic lesions. In several studies, an anti-atherosclerotic effect has been attributed to calcium-channel antagonists. This study aimed to investigate whether ET release from cultured human coronary artery smooth muscle and endothelial cells is influenced by the calcium-channel antagonists diltiazem and verapamil. Coronary plaque smooth-muscle cells (SMCs) were isolated from primary stenosis plaque material. Normal coronary smooth muscle and endothelial cells were obtained from organ donors. Addition of diltiazem (5, 15, 25, 50, or 100 micrograms/ml) and verapamil (0.25, 2.5, 25, 50, or 75 micrograms/ml) to the culture medium induced in all three cell types a dose-dependent reduction in ET secretion (coronary plaque SMCs: diltiazem 98.1 +/- 1.5, 94.9 +/- 5.0, 82.0 +/- 6.4**, 63.3 +/- 3.7***, 38.9 +/- 2.4***; control 108.4 +/- 2.8; verapamil 97.0 +/- 7.7, 91.9 +/- 5.5, 67.3 +/- 4.5**, 30.6 +/- 3.0***, 27.6 +/- 2.2***; control 103.4 +/- 6.1 pg/10(4) cells, n = 6; normal coronary SMCs: diltiazem 9.6 +/- 0.7, 8.7 +/- 0.6, 5.4 +/- 0.5***; 3.7 +/- 0.5***, 3.2 +/- 0.4***; control 10.7 +/- 0.5; verapamil 10.3 +/- 0.9, 10.0 +/- 0.7, 6.6 +/- 0.5***, 4.0 +/- 0.3***, 3.0 +/- 0.3***; control 11.1 +/- 0.6 pg/10(4) cells, n = 6; means +/- SEM, **p < 0.01, ***p < 0.001 vs. control). These data suggest that ET release from cultured coronary smooth muscle and endothelial cells is decreased by diltiazem and verapamil. In further studies, it remains to be elucidated whether the local application of diltiazem or verapamil might have a beneficial effect on the progression of coronary atherosclerosis.

Effect of high dose verapamil on restenosis after peripheral angioplasty

OBJECTIVES

We sought to determine whether treatment with high dose verapamil prevents restenosis in patients at high risk for reoccurrence after successful percutaneous transluminal coronary angioplasty (PTCA).

BACKGROUND

Restenosis is the major limitation of PTCA. Calcium antagonists have demonstrated some potential as inhibitors of this process.

METHODS

A total of 98 patients with peripheral occlusive arterial disease (POAD), stable angina pectoris, mild hypertension and at least one additional risk factor increasing the likelihood of restenosis after angioplasty were selected for this placebo-controlled, double-blind, randomized trial. Verapamil (240 mg twice daily) or placebo was taken for 6 months. Efficacy variables assessed before and after angioplasty and at 6 weeks and 6 months after PTCA included thickness of the intima/media complex degree of stenosis, interventricular septal thickness, crurobrachial pressure ratios of dorsalis pedis and posterior tibial arteries, distance to claudication and total vessel diameter.

RESULTS

No significant intergroup differences emerged before or immediately after PTCA. Six weeks after angioplasty, a significant thickening of the intima/media complex in the treated vascular segment of 14.3% occurred in the placebo group versus 0% among verapamil patients (p < 0.01). At 6 months, the intima/media thickness was 35.7% greater in the placebo group but had decreased by 14.3% in the verapamil group (p < 0.001). At 6 months, a marked reduction in septal thickness was observed in the verapamil group versus that in the placebo group (p < 0.001). The rate of restenosis was also significantly lower in the verapamil group (p < 0.001). Few minor side effects were reported.

CONCLUSIONS

In patients with POAD at increased risk for restenosis, the administration of high dose verapamil prevented recurrent stenosis for 6 months after successful peripheral angioplasty and was well tolerated.

Use of calcium channel antagonists in myocardial revascularization procedures

Calcium channel antagonists possess a number of properties that may be beneficial after revascularization procedures. Therefore, we present an overview of the use of these drugs after percutaneous intervention in the Coronary Angioplasty Versus Excisional Atherectomy Trial (CAVEAT), and compare the results in CAVEAT with those in published randomized trials. Also reviewed are the use of calcium channel antagonists to control perioperative hypertension, reduce myocardial necrosis, and prevent arrhythmias during cardiopulmonary bypass.

Verapamil: a review of its pharmacological properties and therapeutic use in coronary artery disease

Verapamil has well proven efficacy in the treatment of patients with hypertension, and early studies indicated its efficacy in the treatment of coronary artery disease. The efficacy of verapamil relative to placebo in patients with stable angina pectoris is confirmed, and the drug is at least as effective as nifedipine, propranolol or metoprolol and of similar efficacy to bepridil and nicardipine when administered as a conventional or sustained release formulation. Verapamil is the first calcium antagonist to be shown in a double-blind study to significantly reduce mortality and reinfarction rate after acute myocardial infarction in patients without heart failure. In these patients, the reduction in mortality achieved with verapamil was similar to that reported with beta-adrenoceptor antagonists, suggesting that verapamil may be a suitable alternative to beta-blockers as secondary prevention in patients intolerant of these drugs. Recurrence of stenosis in patients who successfully undergo percutaneous transluminal coronary angioplasty (PTCA) limits the usefulness of the procedure. Verapamil has recently been shown to significantly reduce the rate of restenosis in patients with stable angina at risk of recurrence, although these initial results require confirmation. Verapamil, therefore, is effective in the treatment of patients with stable angina pectoris, appears to be an alternative to beta-blockers in selected patients as late start secondary prevention after acute myocardial infarction and has a potential role in preventing recurrent stenosis after PTCA, if initial results are confirmed.

Role of calcium channel blockers in reducing acute ischaemia and preventing restenosis in PTCA

Calcium channel blockers (calcium antagonists) are widely used before, during and after percutaneous transluminal coronary angioplasty (PTCA). When administered during PTCA, calcium channel blockers may be beneficial in decreasing regional ischaemia in patients with proven or suspected variant angina, as a result of their cardioprotective effects, their ability to enhance collateral flow, and their antispastic effects at the epicardial level. More recently, the agents have also proven to be effective in patients who have developed "no-reflow' phenomenon during PTCA. Preliminary findings suggest that calcium channel blockers may also have potential benefits when administered after angioplasty. The combined results of 5 studies, evaluating a total of 919 patients, showed a trend towards angiographic reduction in restenosis. These observations are of interest but may be due to reporting bias. In conclusion, calcium channel blockers are effective in reducing ischaemia induced by PTCA. These agents may, thus, be appropriate in high risk patients. Further large studies examining the effects of calcium channel blockers on restenosis are required to confirm the observations available to date.

Restenosis following coronary angioplasty: clinical presentations and therapeutic options

Restenosis following angioplasty is an iatrogenic disease of increasing frequency. Restenosis may be defined in terms of either angiographic or clinical criteria. Definitions of angiographic restenosis have varied in different studies, accounting in part for the differences in reported restenosis rates. Most studies now define angiographic restenosis as either a > 50% loss of initial gain or an absolute lesion stenosis of > or = 50% at follow-up angiogram. Common clinical end points used in defining restenosis include recurrent angina, need for repeat revascularization, or myocardial infarction. Despite technical advances and multiple pharmacologic interventions, most studies have found that the incidence of angiographic restenosis remains in the range of 40%; in none of these studies, however, was complete angiographic follow-up obtained, and thus actual restenosis rates may be somewhat higher. In several studies, clinical restenosis has been found to occur in approximately 36-40% of patients. Thus, a minority of patients with angiographic restenosis have no clinical manifestations. Most patients who develop symptoms of restenosis develop these symptoms within the first 3 months after angioplasty. The presenting symptom in the majority of these patients is progressive exertional angina. Patients occasionally will present with unstable angina and only rarely with acute myocardial infarction. In patients who present with recurrent chest pain, several features have been found to be helpful in predicting whether they will have angiographic restenosis at follow-up angiography. Patients who present 1-6 months after angioplasty with typical anginal symptoms have a high likelihood of having angiographic restenosis. By contrast, patients who present more than 6 months after percutaneous transluminal coronary angioplasty with recurrent chest pain are more likely to have new, significant coronary lesions to account for their symptoms. Noninvasive testing in patients with clinical presentations suggestive of restenosis can, in general, add only modest information in predicting whether restenosis is indeed present. A negative exercise thallium test appears to have a high specificity in ruling out restenosis and may be helpful in patients who present with more atypical symptoms. Repeat angioplasty is the therapy most frequently utilized to treat restenosis, although coronary artery bypass surgery or medical therapy may be reasonable alternative therapies. Clinical success rates with repeat angioplasty are > 90%, and major complications are rare; however, restenosis will recur in a significant percentage of these patients. Some patients who develop such recurrent restenoses will ultimately benefit from a strategy of repeat angioplasties, although many will require surgical revascularization.

Prevention of restenosis after coronary angioplasty: towards a molecular approach?

Restenosis after coronary angioplasty, the main limitation of interventional cardiology, remains an unsolved issue. The failure to-date of all pharmacological attempts at prevention has prompted the development of alternative strategies. A mechanistic approach to the problem of restenosis is based on the assumption that creating a more satisfactory acute angioplasty result would reduce the development of restenosis. With the exception of coronary stenting, however, none of the new angioplasty devices have convincingly reached this goal. Furthermore, recent advances in the field of vascular biology have opened new avenues for a molecular approach of restenosis. Better understanding of the pathophysiology of restenosis, in conjunction with high-pace development of catheter, polymer, and virus technologies, provide opportunities to deliver agents--drugs, genes, or antisense oligonucleotides--locally, at the site of angioplasty to interfere specifically with the restenosis process. Some of these molecular strategies are currently being investigated in animal models. Clinical application of a molecular approach to prevent restenosis, however, will require close collaboration between physicians, molecular biologists, and bio-engineers.

Platelet aggregability in vivo is attenuated by verapamil but not by metoprolol in patients with stable angina pectoris

The effects of 1 month of treatment with either verapamil or metoprolol on several aspects of platelet function were studied at rest and during physical exercise or mental stress in patients with stable angina pectoris participating in the Angina Prognosis Study in Stockholm. Platelet aggregability was measured by filtragometry ex vivo, which reflects platelet aggregability in vivo and by Born aggregometry in vitro. Platelet secretion in vivo was assessed by measurements of beta-thromboglobulin in plasma. Verapamil reduced plasma norepinephrine levels (from 2.6 +/- 1.0 to 2.2 +/- 1.0 nmol/L; p < 0.01) and attenuated platelet aggregability at rest (filtragometry readings were prolonged from 219 to 295 seconds; p < 0.05, n = 46). Aggregability in platelet-rich plasma was not influenced. Metoprolol did not significantly affect filtragometry readings (n = 58) or aggregability in vitro (there was a tendency toward enhanced adenosine diphosphate sensitivity; p = 0.08). beta-thromboglobulin levels were low (approximately 25 ng/ml) and not influenced by either treatment. Physical exercise (bicycle ergometry) increased platelet aggregability in vivo both before and after drug treatment. Verapamil also attenuated platelet aggregability after exercise, whereas metoprolol had no such effect. Platelet function was not seriously altered by mental stress (Stroop's color word test) despite significant effects on hemodynamics and plasma catecholamines either before or after treatment with either drug. Thus, verapamil attenuates platelet aggregability in patients with stable angina pectoris, whereas metoprolol has no such effect.