Late restenosis after emergent coronary angioplasty for acute myocardial infarction: comparison with elective coronary angioplasty

Early experience with a helical coronary thrombectomy device in patients with acute coronary thrombosis

OBJECTIVE

To report our experience with a new thrombectomy device (X-SIZER(TM)) in patients with angiographically visible thrombus or total coronary occlusion in the setting of acute coronary syndromes.

DESIGN

A safety and feasibility study in the use of the X-SIZER during intervention in patients with acute coronary syndromes.

PATIENTS

35 patients, age range 31 to 83 years (mean 60).

SETTING

University Hospitals of Coventry and Warwickshire NHS Trust (tertiary referral centre).

INTERVENTIONS

The indication for intervention was primary or salvage percutaneous coronary intervention for acute myocardial infarction in 17 of the 35 patients; unstable angina or non-ST-elevation myocardial infarction in 10; and unstable postinfarct angina in eight. Abciximab was given in 11 patients.

MAIN OUTCOME MEASURES

Device success (successful deployment of the device at the site of the lesion with resultant improvement in TIMI flow); clinical success (no residual stenosis at the end of the procedure with no in-hospital major adverse coronary events).

RESULTS

Successful use of the device was achieved in 26 of the 35 cases. It failed to cross the lesion in five and failed to improve TIMI flow despite crossing the lesion in four. Clinical success was achieved in 30 of the 35 cases. Device related complications occurred in two cases (vessel perforation) and there was one intraprocedural death (acute myocardial infarction with cardiogenic shock).

CONCLUSIONS

Thrombectomy with the X-SIZER catheter system appears promising in percutaneous coronary intervention where thrombus extraction is considered necessary before stent implantation.

Randomized, placebo-controlled trial of platelet glycoprotein IIb/IIIa blockade with primary angioplasty for acute myocardial infarction. ReoPro and Primary PTCA Organization and Randomized Trial (RAPPORT) Investigators

BACKGROUND

The benefit of catheter-based reperfusion for acute myocardial infarction (MI) is limited by a 5% to 15% incidence of in-hospital major ischemic events, usually caused by infarct artery reocclusion, and a 20% to 40% need for repeat percutaneous or surgical revascularization. Platelets play a key role in the process of early infarct artery reocclusion, but inhibition of aggregation via the glycoprotein IIb/IIIa receptor has not been prospectively evaluated in the setting of acute MI.

METHODS AND RESULTS

Patients with acute MI of <12 hours' duration were randomized, on a double-blind basis, to placebo or abciximab if they were deemed candidates for primary PTCA. The primary efficacy end point was death, reinfarction, or any (urgent or elective) target vessel revascularization (TVR) at 6 months by intention-to-treat (ITT) analysis. Other key prespecified end points were early (7 and 30 days) death, reinfarction, or urgent TVR. The baseline clinical and angiographic variables of the 483 (242 placebo and 241 abciximab) patients were balanced. There was no difference in the incidence of the primary 6-month end point (ITT analysis) in the 2 groups (28.1% and 28.2%, P=0.97, of the placebo and abciximab patients, respectively). However, abciximab significantly reduced the incidence of death, reinfarction, or urgent TVR at all time points assessed (9.9% versus 3.3%, P=0.003, at 7 days; 11.2% versus 5.8%, P=0.03, at 30 days; and 17.8% versus 11.6%, P=0.05, at 6 months). Analysis by actual treatment with PTCA and study drug demonstrated a considerable effect of abciximab with respect to death or reinfarction: 4.7% versus 1.4%, P=0.047, at 7 days; 5.8% versus 3.2%, P=0.20, at 30 days; and 12.0% versus 6.9%, P=0.07, at 6 months. The need for unplanned, "bail-out" stenting was reduced by 42% in the abciximab group (20.4% versus 11.9%, P=0.008). Major bleeding occurred significantly more frequently in the abciximab group (16.6% versus 9.5%, P=0.02), mostly at the arterial access site. There was no intracranial hemorrhage in either group.

CONCLUSIONS

Aggressive platelet inhibition with abciximab during primary PTCA for acute MI yielded a substantial reduction in the acute (30-day) phase for death, reinfarction, and urgent target vessel revascularization. However, the bleeding rates were excessive, and the 6-month primary end point, which included elective revascularization, was not favorably affected.

Coronary artery stenting for suboptimal PTCA results in acute myocardial infarction in patients treated with Abciximab: early and six-month outcome

Emergent percutaneous transluminal coronary angioplasty (PTCA) is an effective treatment for acute myocardial infarction. However, occasionally results of angioplasty are suboptimal due to coronary dissection or elastic recoil, leading to a high chance of recurrent ischemia. Coronary stents are occasionally employed in such settings, but a high incidence of stent thrombosis was noted by early investigators when stents were placed into areas of active thrombus formation. Since coronary thrombosis and stent thrombosis are both initiated by platelets, the potent antiplatelet agent abciximab might be useful in preventing stent thrombosis. Little information is available concerning early outcome or 6-month clinical event rate when coronary artery stents are placed for suboptimal angioplasty results for acute myocardial infarction in patients given abciximab. We deployed 75 stents as part of angioplasty for acute myocardial infarction in 40 patients given abciximab. All patients had suboptimal angioplasty results leading to stent deployment. Each obtained normal flow angiographically and no stent thrombosis or acute closure was observed. Early mortality occurred in 1 patient. All patients were followed at least 6 months, and no patient died after hospital discharge. Three patients experienced recurrent ischemic events within the first 6 months. Two of these events were due to infarct vessel restenosis. We conclude the combined use of coronary artery stents and abciximab for suboptimal PTCA results during acute myocardial infarction is associated with a low incidence of culprit vessel recurrent ischemic events within 6 months of intervention.

Use of exercise echocardiography to evaluate patients after coronary angioplasty

Exercise echocardiography is a sensitive, specific, and highly accurate method for detecting coronary restenosis and progressive compromise of untreated arterial segments in patients who have undergone percutaneous transluminal coronary angioplasty. It is far more reliable in predicting the status of the coronary anatomy in such patients than exercise electrocardiography or symptomatic status.

Effects of platelet glycoprotein IIb/IIIa receptor blockade by a chimeric monoclonal antibody (abciximab) on acute and six-month outcomes after percutaneous transluminal coronary angioplasty for acute myocardial infarction. EPIC investigators

Percutaneous transluminal coronary angioplasty (PTCA) for acute myocardial infarction is an attractive alternative to thrombolysis, but is still limited by recurrent ischemia and restenosis. We determined whether adjunctive platelet glycoprotein IIb/IIIa receptor blockade improved outcomes in patients undergoing direct and rescue PTCA in the Evaluation of c7E3 for Prevention of Ischemic Complications (EPIC) trial. Of the 2,099 patients undergoing percutaneous intervention who randomly received chimeric 7E3 Fab (c7E3) as a bolus, a bolus and 12-hour infusion, or placebo, 42 underwent direct PTCA for acute myocardial infarction and 22 patients had rescue PTCA after failed thrombolysis. The primary composite end point comprised death, reinfarction, repeat intervention, or bypass surgery. Outcomes were assessed at 30 days and 6 months. Baseline characteristics were similar in direct and rescue PTCA patients. Pooling the 2 groups, c7E3 bolus and infusion reduced the primary composite end point by 83% (26.1% placebo vs 4.5% c7E3 bolus and infusion, p = 0.06). No reinfarctions or repeat urgent interventions occurred in c7E3 bolus and infusion patients at 30 days, although there was a trend toward more deaths in c7E3-treated patients. Major bleeding was increased with c7E3 (24% vs 13%, p = 0.28). At 6 months, ischemic events were reduced from 47.8% with placebo to 4.5% with c7E3 bolus and infusion (p = 0.002), particularly reinfarction (p = 0.05) and repeat revascularization (p = 0.002). We conclude that adjunctive c7E3 therapy during direct and rescue PTCA decreased acute ischemic events and clinical restenosis in the EPIC trial. These data provide initial evidence of benefit for glycoprotein IIb/IIIa receptor blockade during PTCA for acute myocardial infarction.

Restenosis after delayed coronary angioplasty of the culprit vessel in patients with a recent myocardial infarction treated by thrombolysis

BACKGROUND

Clinical follow-up after percutaneous transluminal coronary angioplasty (PTCA) of an infarct-related lesion has demonstrated a low incidence of recurrent symptoms and repeated revascularization. In the absence of systematic angiographic follow-up, this low rate of clinical restenosis may reflect either a truly lower incidence of anatomic restenosis or the lack of recurrent symptoms in patients with extensive infarction in the territory of the restenotic vessel.

METHODS AND RESULTS

We studied 300 consecutive patients who, after a thrombolysis for myocardial infarction, underwent delayed (10.5 +/- 6 days after the myocardial infarction) PTCA of the infarct-related lesion. Procedural success was obtained in 253 patients (84%), and angiographic follow-up was performed in 205 of this group (81%) at a mean of 7.3 +/- 1.9 months. Restenosis (defined as the recurrence of > 50% stenosis) was present in 105 patients (51%). Only 34 of the 105 patients (32%) with angiographic restenosis were symptomatic; the other 68% had clinically silent restenosis. Of these 105 patients, 27 (13% of the total population undergoing follow-up angiography) had reocclusion at the dilated site at follow-up. The severity of the stenosis at follow-up and the late loss in minimal lumen diameter followed a nearly Gaussian distribution if the lesions that were totally occluded at follow-up were excluded. By multivariate analysis, two independent predictors of reocclusion were identified: a small reference diameter (P < .0005) and the presence of collateral vessels before the procedure (P < .01). Only one factor was associated with restenosis in the 178 patients who did not have reocclusion at follow-up; a Thrombolysis in Myocardial Infarction grade < or = 2 before the procedure (P < .0001). At follow-up, there was a significantly (P < .01) higher ejection fraction in patients without restenosis (56.1 +/- 13.4%) and in patients with restenosis without total occlusion (56.0 +/- 13.8%) than in patients with reocclusion (46.4 +/- 13.0%).

CONCLUSIONS

Despite a satisfactory clinical outcome, delayed PTCA of an infarct-related lesion is associated with a high rate of angiographic recurrence. Two distinct mechanisms account for recurrent stenosis: progressive luminal renarrowing as documented after angioplasty of stable lesions and reocclusion of the infarct-related lesion. Only reocclusion is associated with a deterioration in left ventricular function at follow-up.

Restenosis after successful emergency coronary angioplasty for acute myocardial infarction: comparison with elective angioplasty

We investigated the initial and late restenosis rate after successful emergency coronary angioplasty in 64 patients with acute myocardial infarction, and compared these results with those of 100 patients (110 lesions) who had successful angioplasty on an elective basis. The majority of the baseline clinical and angiographic variables were similar in the myocardial infarction and elective groups. The restenosis rate at 1 month was high in patients undergoing emergency angioplasty for acute myocardial infarction (23 vs. 12%). At 3-6 months, the angiographic restenosis rate was low for the infarction group (26 vs. 37%). The overall restenosis rate was similar in the infarction and elective groups (39 vs. 40%). Lesion regression after coronary angioplasty was more frequent in the infarction than in the elective angioplasty group (27 vs. 14%, P < 0.05). These findings suggest that considering the high restenosis rate at 1 month and the lower, but still 20% or more, rate at 3-6 months, a follow-up angiography should be performed both prior to discharge and at 3-6 months after the procedure, in patients with acute myocardial infarction.

Coronary angioplasty in acute myocardial infarction: primary, immediate adjunctive, rescue, or deferred adjunctive approach?

OBJECTIVE

To address the current clinical applications, outcomes, and limitations of coronary angioplasty in the setting of acute myocardial infarction.

DESIGN

We review the results of several large trials in which various strategies of thrombolysis and primary, immediate adjunctive, rescue, or deferred adjunctive coronary angioplasty were used in patients with acute myocardial infarction.

MATERIAL AND METHODS

Four strategies for the utilization of angioplasty in myocardial infarction have been developed and are based on the timing and concurrent use of thrombolytic therapy.

RESULTS

Primary coronary angioplasty without prior thrombolytic therapy is as effective as thrombolytic therapy for salvaging myocardium. Results of a meta-analysis of recent trials suggest potential benefits of increased survival and decreased reinfarction in comparison with the results of thrombolysis in recent trials. Immediate adjunctive angioplasty after thrombolytic therapy has been tested in three large, randomized trials. The results suggest that this strategy is associated with increased risks without benefits of increased survival or improved left ventricular function. Rescue angioplasty may be helpful after failed thrombolytic therapy. Ongoing randomized trials might further clarify the benefits of rescue angioplasty. Because of the inherent difficulty in the noninvasive identification of patients with persistent reocclusion, diagnostic coronary angiography early after thrombolytic therapy may be necessary. Deferred adjunctive angioplasty during the weeks after infarction to prevent recurrent ischemia was not shown to decrease mortality or reinfarction in two large trials.

CONCLUSION

Primary coronary angioplasty is the treatment of choice for patients with contraindications to thrombolytic therapy. Certain high-risk subgroups may also benefit from primary angioplasty.

Factors affecting the restenosis rate after percutaneous transluminal coronary angioplasty

In an open study follow-up angiographies were performed independently from the clinical course on altogether 131 consecutive patients (99 men, 32 women) six months after percutaneous transluminal coronary angioplasty (PTCA). During this period patients received at least 320 mg of aspirin daily. Possible factors affecting the restenosis rate included age, sex, diabetes mellitus, arterial hypertension, abnormal lipid metabolism, smoking, dosage of aspirin administered, degree of stenosis shown by affected vessels before dilatation, number of vascular segments dilated and platelet reactivity. Restenosis was defined as a renewed narrowing of the dilated segment by 50% or more, with an increase in stenosis by at least 20%. In the present study the following restenosis rates were found six month after a primarily successful PTCA: 30% for the entire sample (39 out of 131 patients); 25% in patients with normal platelet function, 50% in those with mildly abnormal platelet function, and 60% in those with frankly abnormal platelet function; 24% in non-diabetic patients and 45% in diabetics. Analysis of the findings showed that abnormal platelet function and the presence of diabetes mellitus were the most important factors in the subsequent development of restenosis after angioplasty. The same also applied in a more restricted manner to the degree of stenosis present before angioplasty.

Silent ischemia after percutaneous transluminal coronary angioplasty: incidence and prognostic significance

OBJECTIVES

The objective of this observational study was to assess the incidence and prognostic significance of silent ischemia after percutaneous transluminal coronary angioplasty.

BACKGROUND

Apart from coronary angioplasty, prognosis of patients with silent ischemia is similar to that of patients with angina pectoris. However, similar data concerning silent ischemia associated with restenosis after coronary angioplasty are missing.

METHODS

A consecutive series of 490 patients was investigated for asymptomatic ischemia on thallium-201 scintigraphy 6 months after successful coronary angioplasty. Repeat angiography was performed in a subgroup of patients with ischemia and repeat angioplasty was performed when clinically indicated. Patients were followed up for 2.2 +/- 0.8 years for cardiac events.

RESULTS

Six months after coronary angioplasty, ischemia was present in 112 (28%) of 405 patients, and 60% of these 112 were asymptomatic. Ischemia was associated with significant stenosis in 97%; in contrast, results of exercise electrocardiography were negative in 74% of patients with scintigraphic ischemia and angiographic restenosis. The degree of restenosis was similar in patients with symptomatic or silent ischemia (80 +/- 16% vs. 81 +/- 21%). The long-term prognosis of patients with silent ischemia was remarkably similar to that of symptomatic patients. A worse outcome of symptomatic patients was found only if repeat coronary angioplasty for restenosis was considered a separate event (p < 0.01). Silent and symptomatic ischemia predicted an increased risk for recurrent ischemic events but not for death.

CONCLUSIONS

Thus, absence of symptoms and negative findings on an exercise electrocardiogram may not reflect a good angioplasty result. In addition, silent ischemia due to restenosis after coronary angioplasty has a significant prognostic importance for recurrent symptomatic ischemic events that may be reduced by repeat angioplasty.

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)

Indications for routine heart-catheterization after CABG and PTCA

Routine heart-catheterization after Coronary Artery Bypass Graft surgery (CABG) or Percutaneous Transluminal Coronary Angioplasty (PTCA) has been advocated to determine the change in bypass graft or dilated coronary artery and native coronary artery status, the effective disease remaining after CABG or PTCA and the relation between progression of disease, left ventricular function and symptomatology. Results of angiographic follow-up data after CABG and PTCA are presented and the practical implications are discussed. The reliability of symptoms, invasive and non-invasive test for the detection of ischemia are considered. Finally, recommendations are made for the indication of routine heart-catheterization after CABG and PTCA.

Outcome after prolonged balloon inflations of greater than 20 minutes for initially unsuccessful percutaneous transluminal coronary angioplasty

Prolonged balloon inflation with or without autoperfusion techniques is a common initial approach to major dissection or abrupt occlusion after percutaneous transluminal coronary angioplasty (PTCA). To assess such a strategy in the setting of unsuccessful angioplasty, 40 patients who underwent prolonged balloon inflations of greater than 20 minutes between January and July of 1991 after initially unsuccessful angioplasty were studied. These patients (median age 59 years) underwent PTCA for progressive or unstable angina (16[40%]), symptomatic or asymptomatic residual stenosis after myocardial infarction (10[25%]), acute myocardial infarction (3[8%]), stable angina (3[8%]), reinfarction (2[5%]), and other indications (6[15%]). The significant stenoses were primarily in the proximal and midportions of the right coronary (53%), left anterior descending (30%) and left circumflex (17%) coronary arteries. Before prolonged balloon inflation, the longest single inflation was 11 +/- 6 minutes and the total time of all inflations was 17 +/- 8 minutes (mean +/- standard deviation). Stenosis was reduced from 91 +/- 9 to 68 +/- 16% before prolonged inflation. After prolonged balloon inflation of 30 +/- 9 minutes, the residual stenosis was 47 +/- 21% (p = 0.0001 vs value before prolonged inflation). Furthermore, improvements in the appearance of filling defects or dissections, or both, occurred in 19 patients (48%). Procedural success was obtained in 32 of 40 patients (80%). Coronary bypass grafting was performed in 8 patients (20%): 4 after unsuccessful PTCA (3 emergently) and 4 electively after initially successful PTCA. Although 5 patients had creatine kinase-MB elevations greater than 20 IU/liter after the procedure, only 1 sustained a Q-wave myocardial infarction. There were no deaths in the hospital.(ABSTRACT TRUNCATED AT 250 WORDS)

The intracoronary administration of urokinase following direct PTCA for acute myocardial infarction reduces early restenosis

Early restenosis after successful percutaneous transluminal coronary angioplasty (PTCA) without antecedent thrombolytic therapy in patients with acute myocardial infarction (AMI) was assessed by performing in-hospital cardiac catheterization in 62 (88%) of 70 consecutive patients. Specific attention was focused on the effectiveness of the intracoronary administration of urokinase in cases with angiographic residual thrombus after successful direct PTCA. The following two treatment regimens were used: PTCA alone (43 patients) and PTCA followed by the intracoronary infusion of urokinase (27 patients). The rate of early restenosis was higher after successful direct PTCA alone (28%) than after direct PTCA followed by intracoronary urokinase (5%). Bleeding complications were no different between the two groups. These findings suggest that intracoronary urokinase can be effective in reducing early restenosis in patients with angiographic residual thrombus after successful direct PTCA. Therefore early restenosis may be related to residual intracoronary thrombus.

Coronary angioplasty performed within the thrombolysis in Myocardial Infarction II study

BACKGROUND

Percutaneous transluminal coronary angioplasty (PTCA) of the infarct-related artery was performed within 42 days of recombinant tissue-type plasminogen activator (rt-PA) administration in 1,414 of the 3,534 patients who participated in the Thrombolysis In Myocardial Infarction (TIMI) II study. Primary angiographic success was obtained in 88.7%, with bypass surgery within 24 hours in 3.3% and death within 24 hours in 0.7% of patients. By 1 year, 25.1% of the 1,414 patients had sustained one or more adverse outcomes including death (3.6%), reinfarction (8.4%), or the need for further revascularization (20%).

METHODS AND RESULTS

Despite these generally favorable results, multivariate testing identified several anatomic and clinical subgroups as having an increased risk ratio (RR) for adverse outcome: Unsuccessful PTCA was more common in patients undergoing protocol-assigned PTCA within 2 hours of rt-PA administration (RR, 2.7; p less than 0.001) and in patients over age 70 years (RR, 1.7; p = 0.034). The need for further revascularization within 1 year was increased in the 30.4% of patients with multivessel disease (RR, 2.5; p less than 0.001), patients with prior angina (RR, 1.4; p less than 0.006), or those undergoing ischemia-driven PTCA within 15 hours of rt-PA administration (RR, 1.7; p = 0.022). The risk of death or recurrent infarction within 1 year was increased by the presence of multivessel disease (RR, 1.6; p = 0.007) or prior angina (RR, 1.5; p = 0.014).

CONCLUSIONS

These observations do not necessarily apply to patients undergoing primary PTCA (or PTCA after other thrombolytic agents); however, they do offer a unique yardstick against which to evaluate the results of PTCA in myocardial infarction.

Coronary restenosis: what have we learned from angiography?

Coronary restenosis remains a major problem for interventional cardiology not only by virtue of its frequency, but also because of the current inability to prevent it. Symptomatic status and non-invasive evaluation have been used to study restenosis, but both lack specificity and sensitivity, particularly in patients with multivessel disease. Angiography remains the reference standard. Several arbitrary definitions have been used, some related to visual estimates of coronary stenosis and others to quantitative angiographic techniques. In another approach, linear modeling is used to assess minimal luminal diameter of lesions on restudy. Although angiographic studies have been essential in the study of restenosis, questions concerning the underlying mechanism and pathophysiology remain. The development of animal models that closely resemble human restenosis should allow evaluation of pathophysiologic mechanisms and development of new strategies to prevent the problem.

Submaximal exercise thallium-201 SPECT for assessment of interventional therapy in patients with acute myocardial infarction

Submaximal thallium-201 stress testing has been shown to provide important diagnostic and prognostic information in patients with acute myocardial infarction. The purpose of this investigation was to evaluate the diagnostic value of early submaximal stress testing and thallium-201 single photon emission computed tomography (SPECT) after interventional therapy. Scintigraphic results from 56 patients with infarctions, who underwent acute thrombolytic therapy, angioplasty, or both, were compared with late (6 weeks) functional outcome as assessed by radionuclide ventriculography and with results of discharge coronary angiography. A linear correlation was found between the extent of thallium-201 SPECT perfusion defect and late ventricular function (r = 0.74, p less than 0.01). Forty-two percent of patients with large SPECT perfusion defects had normal left ventricular ejection fractions, suggesting an overestimation of infarct size by early imaging. Sensitivity and specificity of thallium-201 SPECT for detection of coronary artery stenosis in noninfarct territories was 57% and 46%, respectively, indicating limited diagnostic definition of extent of underlying coronary artery disease. Results of follow-up coronary angiography showed a significant relationship between the size of the initial perfusion defect and early restenosis or reocclusion of the infarct artery. Thus the extent of early thallium-201 perfusion defects correlates with late functional outcome but appears to overestimate the degree of injury. Submaximal thallium-201 stress testing allows only limited characterization of underlying coronary artery disease. Early assessment of infarct size may identify a patient population at high risk for reocclusion of the infarct artery.

Update on mechanical intervention in acute myocardial infarction

The role of pharmacologic interventions in acute myocardial infarction (i.e., a combination of intravenous nitroglycerin, intravenous beta-blocker, oral aspirin, and intravenous thrombolysis), has become more standardized, whereas the role of mechanical intervention remains to be defined. Mechanical intervention includes percutaneous transluminal coronary angioplasty (PTCA) and coronary artery bypass grafting. The number of carefully controlled, randomized trials is limited, particularly with surgery. Nevertheless, in optimal circumstances, when performed within the first few hours of myocardial infarction, surgery can be beneficial in reducing mortality, especially with anterior location of infarct. Surgery may not prevent reinfarction. However, the results of nonrandomized surgical trials done 10 years ago are difficult to compare with modern-day treatment of myocardial infarction with the availability of new agents and PTCA. Angioplasty can be performed safely in the acute phase of myocardial infarction but may not be the ideal choice for all patients. The results may be more optimal if performed when the patient is stable. Clinical factors associated with favorable and unfavorable outcomes have been identified. Mortality is not significantly affected by early versus late PTCA. Certain selected patients benefit from PTCA, particularly those in cardiogenic shock, in whom PTCA has made a dramatic improvement in outcome. To achieve maximal benefit, intervention should be performed early, within the first hours of symptoms. Further well-designed studies may help clarify the role mechanical techniques will play in future combinations of interventional therapy.

Coronary angioplasty after intravenous streptokinase in acute myocardial infarction: influence of restenosis on clinical outcome and left ventricular function

The importance of recurrence of stenosis on clinical outcome and left ventricular function was studied in a consecutive series of patients with acute evolving myocardial infarction (maximal duration of pain 4 h) and thrombolysis (1.5 x 10(6) units of streptokinase intravenously over 60 min) with recanalized single-vessel disease and subsequent successful coronary angioplasty. Coronary angioplasty was performed in 76 patients between 24 hours and 8 days (mean interval 3.3 days) after thrombolysis and was successful in 86% (65/76). The in-hospital reinfarction rate was 5.2% (2 acute and 2 in-hospital reinfarctions). Repeat angiography after a mean interval of 5.9 months revealed a 39% (24/62) restenosis rate (21 restenoses, 3 reocclusions). Restenoses were associated with significantly more clinical complaints (21% vs. 62%; p less than 0.001). Left ventricular function analysis showed significant improvement in the mean global ejection fraction (6.6 +/- 6.0%; p less than 0.001) and mean regional wall motion of the infarct zone (6.2 +/- 8.2%; p less than 0.01) only in patients without restenosis. Recovery of left ventricular function was more evident in inferior than in anterior wall infarctions. In contrast, patients with restenosis had no change in left ventricular function. Thus, the present study demonstrates the adverse influence of restenosis on recovery of left ventricular function and clinical outcome.

Feasibility and cost-saving potential of outpatient cardiac catheterization

To determine the feasibility and cost-saving potential of substituting outpatient for inpatient cardiac catheterization, 986 consecutive procedures were studied at a large referral hospital. Patients were classified prospectively as to their eligibility for outpatient cardiac catheterization according to published guidelines. Resource consumption was recorded, and cost savings were then calculated by analyzing the specific supply and personnel costs that could change as a result of inpatient versus outpatient status. Of the total of 986 patients who underwent diagnostic catheterization, 240 (24%) were outpatients, 279 (28%) were inpatients but had no exclusion criteria for outpatient catheterization and 467 (47%) were inpatients who had one or more exclusions for outpatient catheterization. The most common reasons for exclusion from outpatient catheterization were congestive heart failure (22%), unstable angina (15%), noncoronary heart disease (14%), recent myocardial infarction (11%) and severe noncardiac disease (9%). Inpatients with no exclusions for the outpatient procedure tended to be sicker than outpatients because they were older (p = 0.002), had a lower ejection fraction (p = 0.009) and had more triple vessel coronary artery disease (p less than 0.0001). The cost of the catheterization procedure itself was not different between inpatients and outpatients. Laboratory testing was more frequent among inpatients, however, and "room and board" costs were significantly higher. Although the difference in hospital charges for inpatients and outpatients was $580, a rigorous analysis indicated that the potential cost savings was only 38% of this amount, or $218 per eligible patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of restenosis after elective percutaneous transluminal coronary angioplasty using the exercise treadmill test

To determine the value of a 6-month exercise treadmill test for detecting restenosis after elective percutaneous transluminal coronary angioplasty (PTCA), 303 consecutive patients with successful PTCA and without a recent myocardial infarction were studied. Among the 228 patients without interval cardiac events, early repeat revascularization or contraindications to treadmill testing, 209 (92%) underwent follow-up angiography, and 200 also had a follow-up treadmill test and formed the study population. Restenosis (greater than or equal to 75% luminal diameter stenosis) occurred in 50 patients (25%). Five variables were individually associated with a higher risk of restenosis: recurrent angina (p = 0.0002), exercise-induced angina (p = 0.0001), a positive treadmill test (p = 0.008), more exercise ST deviation (p = 0.04) and a lower maximum exercise heart rate (p = 0.05). However, only exercise-induced angina (p = 0.002), recurrent angina (p = 0.01) and a positive treadmill test (p = 0.04) were independent predictors of restenosis. Using these 3 variables, patient subsets could be identified with restenosis rates ranging from 11 to 83%. The exercise treadmill test added independent information to symptom status about the risk of restenosis after elective PTCA. Nevertheless, 20% of patients with restenosis had neither recurrent angina nor exercise-induced ischemia at follow-up. For more accurate detection of restenosis, the exercise treadmill test must be supplemented by a more definitive test.

Exercise treadmill testing is a poor predictor of anatomic restenosis after angioplasty for acute myocardial infarction

This study evaluated whether an exercise treadmill test could predict restenosis in 289 patients 6 months after a successful emergency angioplasty of the infarct-related artery for acute myocardial infarction. After excluding those with interim interventions (64), medical events (36), or medical contraindications to follow-up testing (25), both a treadmill test and a cardiac catheterization were completed in 144 patients, 88% of those eligible for this assessment. Four patients with left bundle branch block or pacemaker rhythm at the time of treadmill testing were also excluded from analysis. Of six follow-up clinical and treadmill variables examined by multivariable logistic regression analysis, only exercise ST deviation was independently correlated with restenosis at follow-up (chi 2 = 5, p = 0.02). The clinical diagnosis of angina at follow-up, although marginally related to restenosis when considered by itself (p = 0.04), did not add significant information once ST deviation was known. The sensitivity of ST deviation of 0.10 mV or greater for detecting restenosis was only 24% (13 of 55 patients), and the specificity was 88% (75 of 85 patients). The sensitivity of exercise-induced ST deviation for detection of restenosis was not affected by extent or severity of wall motion abnormalities at follow-up, by the timing of thrombolytic therapy or of angioplasty, or by the presence of collateral blood flow at the time of acute angiography. A second multivariable analysis evaluating the association of the same variables with number of vessels with significant coronary disease at the 6-month catheterization found an association with both exercise ST deviation (p = 0.003) and exercise duration (p = 0.04). Angina symptoms and exercise treadmill test results in this population had limited value for predicting anatomic restenosis 6 months after emergency angioplasty for acute myocardial infarction.

Adequate heparinization during PTCA: assessment using activated clotting times

Heparinization during PTCA is often done empirically with an initial 10,000 unit bolus of heparin and subsequent additional boluses as deemed necessary to prevent thrombus formation and fibrin deposition. However, the initial 10,000 unit bolus may not result in adequate systemic anticoagulation in every patient, exposing some patients to risk of thrombus at the angioplasty site and subsequent reocclusion. In this non-randomized study, we assessed systemic coagulation during PTCA by retrospectively analyzing activated clotting times obtained in 108 consecutive patients. All patients had normal baseline prothrombin times and activated partial thromboplastin times. Patients who were on heparin prior to PTCA were excluded. Based on data from studies on heparinization during extracorporeal bypass an activated clotting time (ACT) of greater than 300 seconds was required. Twelve patients (11%) were observed to have activated clotting times of below 300 seconds after an initial 10,000 unit bolus of heparin. These patients required an additional 3,000-10,000 units of heparin to have systemic anticoagulation during PTCA. Symptoms of stable or unstable angina had no significant effect on heparin requirement, although there was a trend toward greater heparin resistance in unstable angina. We conclude that it is important to monitor the status of anticoagulation during PTCA, for 11% of patients undergoing PTCA require additional initial heparin bolus to achieve an ACT greater than 300 seconds and to be effectively anticoagulated. Careful monitoring of heparinization during PTCA may reduce the incidence of thrombosis.

Influence of inflation pressure and balloon size on the development of intimal hyperplasia after balloon angioplasty. A study in the atherosclerotic rabbit

To evaluate the effect of balloon size and inflation pressure on acute and subsequent outcome following balloon angioplasty (BA), 70 New Zealand White rabbits with bilateral femoral atherosclerosis were assigned to four groups: group 1, oversized balloon, low inflation pressure (n = 35 vessels; balloon size, 3.0 mm/inflation pressure, 5 atm); group 2, oversized balloon, high inflation pressure (n = 36; 3.0 mm/10 atm); group 3, appropriate size, low inflation pressure (n = 17; 2.5 mm/5 atm); and group 4, appropriate size balloon, high inflation pressure (n = 19; 2.5 mm/10 atm). Angiograms were obtained before, 10 minutes after, and 28 days after BA and read by two blinded observers using electronic calipers. The in vivo balloon-to-vessel ratio was measured for each group. There were eight non-BA controls. Rabbits were sacrificed either immediately (n = 34) or at 28 days after BA (n = 36), with the femoral vessels pressure perfused for histologic and morphometric analysis. The latter was performed at 28 days only. Absolute angiographic diameters increased in all groups immediately after BA (p less than 0.01). Acute angiographic success, defined as greater than 20% increase in luminal diameter, was higher using high inflation pressure (group 2, 32/36 [89%] and group 4, 16/19 [84%] vs. group 1, 23/35 [66%] and group 3, 9/17 [53%]; p less than 0.05). A 3.0-mm balloon resulted in significant oversizing irrespective of inflation pressure (balloon-to-vessel ratio, 1.5 +/- 0.1 vs. 1.1 +/- 0.1 to 1, for the 2.5-mm balloon). Vessels exposed to high inflation pressure had a significantly higher incidence of mural thrombus, dissection (p less than 0.01), and medial necrosis versus low pressure (p less than 0.05). At 28 days, the rates of restenosis (defined as greater than 50% loss of initial gain) were 14/20 (70%), 11/16 (69%), 5/10 (50%), and 5/10 (50%) for groups 1 through 4 (p = NS; a trend in favor of the groups using an oversized balloon). There was an increase in the degree of intimal hyperplasia by morphometric analysis in all groups, being most marked in group 2 (oversized balloon and high inflation pressure, 1.7 +/- 0.9 vs. 0.5 +/- 0.2 mm for controls, p less than 0.001). We reached two conclusions. First, all protocols resulted in a significant increase in luminal diameter immediately after angioplasty with the highest success rate in vessels subjected to high pressure dilatation.(ABSTRACT TRUNCATED AT 400 WORDS)

Intracoronary stents: will they fulfill their promise as an adjunct to angioplasty?

Coronary angioplasty as it is now performed has several limitations, including abrupt early arterial closure and delayed restenosis. To obviate these problems and to enhance the safety of the technique, several intracoronary stenting devices have been developed and are under investigation. This report reviews the scientific rationale behind stenting, the results of stenting in animal models and the early results in humans. In early clinical investigation, restenosis appears uncommon but abrupt, presumably thrombotic, occlusion has been reported despite aggressive anticoagulation. As long as the potential for this problem remains and the long-term consequences of placing these devices into arteries of great functional importance remain unknown, stent placement must be undertaken with great caution and should be performed under carefully monitored circumstances with meticulous patient follow-up.

Intense microvascular constriction after angioplasty of acute thrombotic coronary arterial lesions

Immediately after balloon dilation of a fresh thrombotic coronary lesion, 5 patients had angina, ST segment elevation, and a striking reduction of blood flow in the dilated artery. A mean (SEM) pressure gradient across the dilated lesion of only 3(1) mm Hg and an average minimum lesion diameter of 1.7 mm indicated that the decline in resting blood flow was not due to obstruction at the site of the original lesion. Neither distal vascular emboli nor side branch occlusions were visible on the angiogram. An increase in distal coronary artery pressure during a subsequent balloon inflation suggested that the site of vasoconstriction was distal to the origin of collateral vessels. The syndrome lasted 48-80 min and was not reversed with nitroglycerin or thrombolytic drugs. Papaverine lessened the syndrome transiently on one occasion. Such microvascular constriction, caused by release of potent vasoconstrictors from the clot, may partly explain the failure of emergency angioplasty to reduce infarct size in acute myocardial infarction.

Repeat percutaneous transluminal coronary angioplasty and predictors of recurrent restenosis

One hundred seventeen consecutive patients undergoing repeat percutaneous transluminal coronary angioplasty (PTCA) were studied to assess procedural success and recurrent restenosis rates. Clinical, anatomic and procedural variables were examined as predictors of recurrent restenosis using stepwise logistic regression analysis. Primary success was achieved in 114 patients (97.5%). One patient (0.8%) died after acute occlusion. No other in-hospital complications were encountered. After a mean follow-up interval of 218 +/- 160 days, 72 of 114 successfully dilated patients (63%) remained angina free. There were no late deaths. Three patients (2.6%) experienced a late myocardial infarction. Follow-up arteriography was performed in 100 patients (88%), of whom 32% had recurrent restenosis (greater than 50% luminal diameter narrowing). On univariate analysis, the presence of 3 clinical variables at repeat PTCA was associated with significantly higher recurrent restenosis rates compared with their absence, that is, unstable angina (48 vs 20%, p = 0.003), diabetes (61 vs 26%, p = 0.003) and hypertension (46 vs 18%, p = 0.003). Patients with recurrent restenosis had a shorter interval between first and second PTCA compared with those who remained patent (136 +/- 116 vs 214 +/- 163 days, p = 0.018). Multivariate analysis confirmed unstable angina, diabetes and hypertension as independent predictors of recurrent restenosis. Repeat PTCA may be performed for restenosis with a high likelihood of success and low incidence of complications. The rate of recurrent restenosis is similar to that reported for initial angioplasty. Patients with unstable angina, diabetes and hypertension appear to be at higher risk for recurrent restenosis.

Survival and cardiac event rates in the first year after emergency coronary angioplasty for acute myocardial infarction

One year survival and event-free survival rates were analyzed in 342 patients with acute myocardial infarction who were consecutively enrolled in a treatment protocol of early intravenous thrombolytic therapy followed by emergency coronary angioplasty. Ninety-four percent of the patients achieved successful reperfusion, including 4% with failed angioplasty whose perfusion was maintained by means of a reperfusion catheter before emergency bypass surgery. The procedural mortality rate was 1.2% and the total in-hospital mortality rate was 11%. Ninety-two percent of surviving nonsurgical patients who underwent repeat cardiac catheterization were discharged from the hospital with an open infarct-related artery. The related cumulative 1 year survival rate for all patients managed with this treatment strategy was 87%, and the cardiac event-free survival rate was 84%. The 1 year survival for hospital survivors was 98% and the infarct-free survival rate was 94%. Multivariable analysis identified the following factors as independent predictors of subsequent cardiovascular death: cardiogenic shock, greater age, lower ejection fraction, female gender and a closed infarct-related vessel on the initial coronary angiogram. Among patients with cardiogenic shock, despite a 42% in-hospital mortality rate, only 4% died during the first year after hospital discharge. Similarly, the in-hospital and 1 year postdischarge mortality rates were 19 and 4%, respectively, for patients with an initial ejection fraction less than 40, and 25 and 3%, respectively, for patients greater than 65 years. An aggressive treatment strategy including early thrombolytic therapy, emergency cardiac catheterization, coronary angioplasty and, when necessary, bypass surgery resulted in a high rate of infarct vessel patency.(ABSTRACT TRUNCATED AT 250 WORDS)