Angiographic features in the infarct-related artery after intracoronary urokinase followed by prolonged anticoagulation. Role of ruptured atheromatous plaque and adherent thrombus in acute myocardial infarction in vivo

Clinical Manifestations and Prognosis of Embolism Caused by Filler Injection in Different Facial Regions

Background

Embolism is a serious complication after facial filling, with a usually poor prognosis of the symptoms after embolism. The authors systematically reviewed reported cases of facial vascular embolism, explored the relationship between the location and material used for facial filling and occurrence of vascular embolism, and assessed the prognosis of complications after vascular embolism.

Methods

This study provides a systematic review of published cases of vascular embolism after facial filling. A summary of the filling materials and filling sites for each case, the adverse reactions and embolized blood vessels, a recording of the time when each patient experienced adverse reactions and started treatment, and a presentation of their prognosis are provided.

Results

The frontal, eyebrow, and nose are common filling sites causing facial embolism. The main clinical manifestations after embolism were visual impairment, skin necrosis, and ptosis. The prognosis of visual impairment after embolization was poor, whereas skin necrosis and ptosis generally improved after treatment.

Conclusions

This article aimed to review the clinical manifestations, therapies, and prognosis of embolism after facial filling. A better understanding of these complications can help clinicians to detect the occurrence of complications as early as possible and give patients timely treatment.

Left ventricular free wall rupture possibly induced by coronary spasm. Surgical repair in the emergency room

A 68-year-old woman complained of chest discomfort after a traffic accident in which she driving hit a child. At about twenty-five minutes later, she went into sudden cardiogenic shock due to acute myocardial infarction caused by non-occlusive intracoronary thrombosis without significant organic coronary stenosis and without any sign of extraluminal contrast pooling on coronary angiography. She was transported to our emergency room by ambulance because of cardiac tamponade caused by a left ventricular free wall rupture following the acute myocardial infarction. On arrival, she was near cardio-pulmonary arrest on intraaortic balloon pumping. We performed emergency open cardiac massage and pericardiotomy. The hairline perforation responsible for the blowout-type left ventricular free wall rupture was successfully closed with Teflon-reinforced sutures. In conclusion, it was strongly suspected that the present case of left ventricular free wall rupture was caused by acute myocardial infarction due to intracoronary thrombosis following coronary spasm without significant organic coronary stenosis or rupture of atheromatous plaque.

Improving the Efficacy and Stability of Coronary Reperfusion Following Thrombolysis: Exploring the Thrombin Hypothesis

A major assumption in the treatment of patients with acute myocardial infarction (MI) implies that the speed of coronary arterial reperfusion correlates directly with the overall extent of myocardial salvage, and that the extent of mycardial salvage, in turn, determines the absolute reduction in patient mortality. While a growing experience has made it clear that myocardial salvage-independent (time-independent) mechanisms of benefit also exist, few would argue with the hypothesis that the greatest benefit derived from coronary thrombolysis occurs with early (time-dependent) treatment. Thus, improvements in the efficacy of reperfusion and the stability of reperfusion are likely to have considerable impact on patient outcome.

Racial heterogeneity in coronary artery vasomotor reactivity: differences between Japanese and Caucasian patients

Japanese investigators have provided a substantial contribution in the understanding of coronary vasomotor reactivity. On occasions, their findings have been at variance with those undertaken on caucasian patients, raising speculation that vasomotor differences between races may exist. In a comparative review of the published literature, we evaluated the vasoreactive differences among Japanese and caucasian patients with variant angina or myocardial infarction. In variant angina, Japanese patients appear to have diffusely hyperreactive coronary arteries compared with caucasian people, manifested by their segmental rather than focal spasm, hyperreactive nonspastic vessels and multivessel spasm. These differences may reflect the increased basal tone among Japanese variant angina patients and may relate to controversial differences in endothelial nitric oxide production or autonomic nervous system activity. Provocative vasomotor studies of Japanese patients with a recent myocardial infarction report a higher incidence of inducible spasm than caucasian studies, an observation recently supported by a controlled study. Furthermore, the hyperreactivity was diffuse, occurring in both non-infarct- and infarct-related vessels. These observations support the existence of racial coronary vasomotor reactivity differences but require confirmation in further prospectively conducted studies.

Complex stenosis morphology predicts late reocclusion during follow-up after myocardial infarction in patients with patent infarct-related coronary arteries

BACKGROUND

Whether angiographic morphology of infarct-related residual stenoses continues to affect prognosis after discharge is not known.

METHODS

We studied 175 patients after their myocardial infarction who required nonurgent coronary angioplasty for residual myocardial ischemia. The findings at diagnostic coronary angiography were compared with those before angioplasty (mean of 7 months later). Infarct-related stenoses were classified as complex or smooth. Stenosis progression was defined as >0.5 mm diameter reduction.

RESULTS

One hundred twenty-one (69%) infarct-related stenoses were complex. At restudy, total occlusion was found in 41 (35%) of the infarct-related complex stenoses compared with 7 (13%) smooth stenoses (P = .001). Reocclusion occurred in 16 (55%) of 29 complex infarct-related stenoses with thrombus, compared with 25 (28%) of 88 without thrombus (P = .01). During follow-up, 46 patients (26%) had cardiac events. Of these, 70% had complex lesions at study entry compared with 30% smooth (P < .05).

CONCLUSIONS

Residual angiographically complex stenoses after an uncomplicated myocardial infarction are associated with a greater risk of reocclusion and may predispose to coronary events at follow-up.

Thrombin: Structure, Biochemistry, Measurement, and Status in Clinical Medicine

Thrombin remains a molecule of great interest to scientists and clinicians alike because of its important role in hemostasis, thrombosis, inflammation and vascular remodeling. Yet one of the great challenges has been the inhibition of thrombin generation to a degree that minimizes intravascular thrombosis while preserving physiologic hemostasis. It has become increasingly clear that high levels of anticoagulation with either direct or indirect thrombin antagonists are not beneficial and, in fact, are quite detrimental. Despite the overwhelming shift of interest toward the platelet in clinical trials of acute coronary syndromes, much can be gained through further investigation of coagulation processes responsible for thrombin generation and activity.

Antithrombotic treatment in stable coronary syndromes: long-term intermittent urokinase therapy in end-stage coronary artery disease and refractory angina pectoris

Interventions that modify lipid metabolism and blood coagulation have been shown to favourably influence the natural course of coronary artery disease in terms of the primary prevention and treatment of acute cardiovascular events. Various findings suggest that such interventions may also preserve and enhance myocardial perfusion in the chronic stage of the disease. Long-term intermittent urokinase therapy was developed for patients with end-stage coronary artery disease and refractory angina pectoris. A dose of 500,000 IU of urokinase given intravenously as a bolus three times a week for of 12 weeks reduced symptoms by 70% and was accompanied by objective improvements in myocardial perfusion and an increase of ergometric exercise capacity. The possible therapeutic mechanisms of long-term intermittent urokinase therapy-improvement of rheological blood properties mediated by fibrinogen reduction, thrombolysis of non-occlusive subclinical thrombi, and regression of atherosclerotic plaques-are discussed in the context of other antithrombotic approaches.

Role of plaque size and degree of stenosis in acute myocardial infarction

Angiographically apparent coronary artery stenoses limit coronary flow, produce symptomatic ischemia, and can be targeted for revascularization. Severe stenoses are more likely to occlude than segments without significant stenoses. Coronary angiography underestimates the extent of coronary atherosclerosis. Arterial segments without severe stenoses are much more common, and their risk of occlusion is not zero. Thus, the majority of myocardial infarctions are due to occlusion of arteries that do not contain obstructive coronary stenoses. Consequently, coronary angiography is not able to accurately predict the site of a coronary artery occlusion that subsequently will produce myocardial infarction.

Acute myocardial infarction--the angiographic picture: new insights into the pathogenesis of myocardial infarction

The angiographic appearance of the coronary arteries were examined in 302 patients with stable angina pectoris and compared to 308 patients with acute myocardial infarction, who received high-dose intravenous thrombolytic therapy, in order to elucidate the underlying angiopathological picture in the two diseases. In each group coronary lesions were present in proximal segments of the arteries and were closely related to bifurcations. Lesions were more extensively distributed in the coronary tree in patients with stable angina and they had an average of 5.4 lesions per patient, compared to the acute myocardial infarction group who had only 2.4 lesions. Also, in the acute myocardial infarction patients, four-fifths of the culprit arteries were patent, 104 (34%) had a ruptured plaque, 22 (7%) had an ulcerated plaque and in 190 (62%) the lesions were eccentric. The study shows that patients with myocardial infarction who are suitable for thrombolysis have a unique coronary angiographic picture and the acute episode is caused by sudden rupture of a localized atheromatous plaque which initiates an obstructive thrombotic cascade.

The severity of residual coronary stenosis immediately after thrombolytic therapy does not influence the size of later left ventricular asynergic area

To determine whether the severity of residual coronary artery stenosis immediately after thrombolytic therapy influences the size of later left ventricular (LV) asynergic area, we reviewed coronary angiograms (CAGs) and left ventriculograms (LVGs) of 31 patients with acute myocardial infarction (AMI). All patients received intracoronary urokinase therapy within 6 h after onset of AMI due to total occlusion of the proximal left anterior descending coronary artery (LAD). A dose of 960,000 IU urokinase was infused into the ostium of the left coronary artery over 40 min. Patients in whom antegrade blood flow without delayed distal filling was restored received rigorous anticoagulation. The patients were divided into three groups according to the severity of the coronary lesion immediately after urokinase therapy: 9 patients with complete occlusion in Group 1, 15 with > 90% stenosis in Group 2, and 7 with < 90% stenosis in Group 3. There were no significant differences in the baseline clinical characteristics among the patients in the three groups. The LADs in Group 1 were also totally occluded 1 month after urokinase therapy, the treated vessels in both Groups 2 and 3 were still patent, and patients in Group 2 showed a further reduction in residual stenosis. When LV asynergic area, regional wall motion, and global ejection fraction (EF) were compared among the three groups, no significant differences were demonstrated. In comparison with the data immediately after urokinase therapy, all parameters 1 month after therapy were significantly improved in both Groups 2 and 3.(ABSTRACT TRUNCATED AT 250 WORDS)

Blockade of platelet membrane glycoprotein Ib receptors delays intracoronary thrombogenesis, enhances thrombolysis, and delays coronary artery reocclusion in dogs

Von Willebrand factor and platelet membrane glycoprotein Ib receptors interact to mediate platelet adhesion and thrombogenesis in stenosed and endothelium-injured arteries. We wished to determine whether blocking glycoprotein Ib receptors with a recombinant von Willibrand factor binding domain (VCL) increases the time required for thrombus formation after injury to the coronary arteries. We also wished to determine whether, after thrombolysis with tissue plasminogen activator (TPA), VCL delays or protects against coronary artery reocclusion. Twenty-seven dogs were treated with either saline, VCL, or aspirin before thrombosis was induced in their coronary arteries by electrical injury. The time from injury to the formation of occlusive thrombi was significantly greater with VCL (70 +/- 10 minutes) and aspirin (69 +/- 20 minutes) than with saline (18 +/- 3 minutes, P < .001 and P < .05). Thrombosis was induced in 30 other dogs that then received thrombolytic treatment in four groups. Our major finding was that coronary artery reocclusion occurred in 72 +/- 11 minutes after treatment with TPA (80 micrograms/kg + 8 micrograms.kg-1.min-1) and heparin (200 U/kg) (n = 7); in 142 +/- 24 minutes after TPA, heparin, and VCL (4 mg/kg + 2 mg.kg-1.h-1) (n = 7) (compared with TPA and heparin, P < .05); in 74 +/- 13 minutes after TPA, heparin, and aspirin (5 mg/kg) (n = 8); and in 173 +/- 8 minutes after TPA, heparin, VCL, and aspirin (n = 8) (compared with TPA and heparin, P < .001). Thus, VCL increases the length of time required for thrombus formation in coronary arteries, and, when given with TPA and heparin, delays coronary artery reocclusion more effectively than aspirin.

A new look at coronary angiograms: plaque morphology as a help to diagnosis and to evaluate outcome

Characterization of plaque morphology can provide useful information beyond those generally yielded by the more traditional methods of interpretation of coronary angiograms based on assessment of severity of stenoses and number of diseased vessels. Focus on the culprit coronary lesion in acute myocardial infarction and in unstable angina allows recognition of the complex plaque and of presence of endoluminal thrombi that are closely associated to the mechanisms of the disease. Response to treatment in these clinical situations, and the healing process can be assessed by repeated opacifications of the lesion. The presence of a residual thrombus is associated with a worse clinical outcome and also a higher risk of complication if coronary angioplasty is performed. The prognostic information derived from the morphologic analysis extends to the chronic phase of the disease. The extent score of disease, defined as the sum of coronary artery segments showing a narrowing of any severity marks more severe disease and predicts future progression. Severity of stenosis is also a predictor. More severe lesions will occlude more frequently but most often without clinical consequences. Occlusion of less severe stenosis, on the other hand, leads to acute myocardial infarction or to the other manifestations of acute coronary syndromes. Other morphologic features are also associated with a higher risk of myocardial infarction. These include a geometry favoring blood flow separation and turbulence such as acute inflow and outflow angles of the stenosis and presence of a division within its vicinity. This new look at coronary angiograms may help orient therapy. Patients with angina and a significant stenosis will profit from a corrective intervention. Others with a high extent score should receive a comprehensive program for control of risk factors. Patients with a lesion of borderline significance at risk of activation should be closely monitored, and when clinical symptoms evolve, receive more intensive antithrombotic therapy. Quantification of the morphologic characteristics of the plaque, coupled to new techniques for endovascular imaging should lead in the future to better diagnostic and better risk stratification.

Coronary angiographic findings in infarct-related arteries following 1 month of medical treatment

PURPOSE

We undertook the present study to determine first whether coronary angiographic (CAG) features, suggestive of ruptured atherosclerotic plaque, develop in infarct-related arteries of patients receiving conventional medical therapy without thrombolytic agents, and if they develop, what the incidence is, and second whether the sites where the CAG features develop are specific to infarct-related lesions.

METHODS

We reviewed the CAG findings of 127 consecutive patients one month after myocardial infarction (MI), including 72 consecutive patients who received medical therapy (Group I) and 55 patients who underwent intracoronary urokinase infusion (Group II).

RESULTS

Angiographic evidence of ruptured plaque was present in 24/44 (54.5%) patent infarct-related arteries in Group I and in 27/43 (62.8%) in Group II. Similar findings were only noted in 2/52 (3.8%) patent non-infarct-related arteries with significant stenosis in Group I, and in 0/45 (0.0%) in Group II.

CONCLUSION

On angiography, ruptured plaque was commonly found in patent infarct-related arteries in both groups, and was highly specific for the site of infarction. Thrombolytic therapy seemed to have no apparent effect on lesion morphology 1 month after MI.

Culprit lesion morphology and stenosis severity in the prediction of reocclusion after coronary thrombolysis: angiographic results of the APRICOT study. Antithrombotics in the Prevention of Reocclusion in Coronary Thrombolysis

OBJECTIVES

In the APRICOT study (Antithrombotics in the Prevention of Reocclusion In Coronary Thrombolysis), we sought to determine whether angiographic characteristics of the culprit lesion could predict reocclusion after successful thrombolysis and to analyze the influence of three antithrombotic treatment regimens.

BACKGROUND

After successful thrombolysis, reocclusion is a major problem. Prediction of reocclusion by angiographic data and choice of antithrombotic treatment would be important for clinical management.

METHODS

After thrombolysis, patients were treated with intravenous heparin until initial angiography was performed within 48 h. Patients with a patent infarct-related artery were eligible. Three hundred patients were randomly selected for treatment with coumadin, aspirin (300 mg once daily) or placebo. Patency on a second angiographic study after 3 months was the primary end point of the study.

RESULTS

Reocclusion rate was 25% with aspirin, 30% with coumadin and 32% with placebo (p = NS). Lesions with > 90% stenosis reoccluded more frequently (42%) than did those with < 90% stenosis (23%) (p < 0.01). Reocclusion rate of smooth lesions was higher (34%) than that of complex lesions (23%) (p < 0.05). In lesions with < 90% stenosis, the reocclusion rate was lower with aspirin (17%) than with coumadin (25%) or placebo (30%) (p < 0.01). In complex lesions, the reocclusion rate was lower with aspirin (14%) than with coumadin (32%) or placebo (25%) (p < 0.02). Multivariate analysis showed only stenosis severity > 90% to be an independent predictor of reocclusion (odds ratio 2.31, 95% confidence interval 1.28 to 4.18, p = 0.006).

CONCLUSIONS

Angiographic features of the culprit lesion after successful coronary thrombolysis significantly predict the risk of reocclusion: high grade (> 90%) stenoses reoccluded more frequently. Aspirin was effective only in complex and less severe lesions (< 90% stenosis). These findings should prompt investigation of the effects of an aggressive approach to patients with severe residual stenosis.

Mechanism of benefit of combination thrombolytic therapy for acute myocardial infarction: a quantitative angiographic and hematologic study

OBJECTIVES

The goal of this study was to lend insight into the mechanisms responsible for the beneficial effects of combination thrombolytic therapy.

BACKGROUND

Combination thrombolytic therapy for acute myocardial infarction has been associated with less reocclusion and fewer in-hospital clinical events than has monotherapy.

METHODS

Infarct-related quantitative coronary dimensions and hemostatic protein levels were evaluated in 287 patients with acute myocardial infarction during the early (90-min) and convalescent (7-day) phases after administration of recombinant tissue-type plasminogen activator (rt-PA), urokinase or combination rt-PA and urokinase.

RESULTS

Minimal lumen diameter was similar in the 90-min and 7-day phases after treatment with rt-PA, urokinase and combination rt-PA and urokinase (0.72 +/- 0.45 mm, 0.62 +/- 0.53 mm and 0.75 +/- 0.58 mm, respectively, at 90 min, p = 0.16; and 1.05 +/- 0.56 mm, 1.12 +/- 0.72 mm and 0.94 +/- 0.54 mm, respectively, at 7 days, p = 0.22). In-hospital clinical event and reocclusion rates were less frequent in patients receiving combination therapy than in those receiving monotherapy (25% vs. 38% and 32% for rt-PA and urokinase, respectively, p = 0.084; and 3% vs. 13% and 9% for rt-PA and urokinase, respectively, p = 0.03), but these events were unrelated to early or late coronary dimensions. Patients receiving combination therapy or urokinase monotherapy had significantly higher peak fibrin degradation products (1,307 +/- 860 and 1,285 +/- 898 micrograms/ml vs. 435 +/- 717 micrograms/ml, respectively, p < 0.0001) and lower nadir fibrinogen levels (0.85 +/- 1.00 and 0.75 +/- 0.53 g/liter vs. 1.90 +/- 0.86 g/liter, respectively, p < 0.0001) than did those receiving rt-PA monotherapy. Peak fibrinogen degradation products indirectly correlated (p = 0.004) and baseline (p = 0.026) and nadir (p = 0.089) fibrinogen levels directly correlated with reocclusion.

CONCLUSIONS

Lower in-hospital clinical event and reocclusion rates observed with combination thrombolytic therapy may relate to systemic hematologic factors rather than to the residual lumen obstruction after thrombolysis.

Angiographic findings in the coronary arteries after thrombolysis in acute myocardial infarction

The angiographic appearance of the coronary arteries was examined in 308 patients with acute myocardial infarction (AMI) who received high-dose intravenous thrombolytic therapy. Coronary angiography was performed on day 7 after admission to the hospital. Patients had an average of 2.4 discrete arterial narrowings or obstructions. The narrowings were proximal and related to bifurcations. Four fifths of the culprit arteries were patient; 104 (34%) had a ruptured plaque, 22 (7%) had an ulcerated plaque, and in 190 (62%) the lesions were eccentric. Patients differed from a comparable, previously studied, control series of 302 patients with chronic stable angina pectoris who had more extensive disease. They had 5.7 narrowings/patient, also located proximally and at bifurcations, but more widely distributed in the coronary tree. Patients with AMI who are suitable for thrombolysis have a unique coronary angiographic picture. The data confirm that AMI is caused by sudden rupture of a localized atheromatous plaque that initiates an obstructive thrombotic cascade.

Triggering and hourly variation of onset of arterial thrombosis

Information obtained during the past decade suggests that the onset of myocardial infarction and sudden cardiac death is frequently triggered by daily activities. The importance of physical or mental stress in triggering coronary thrombosis is supported by finding that (1) the frequencies of the onset of myocardial infarction, sudden cardiac death, and stroke show marked circadian variations, with similar increases in the period from 6 AM to noon; (2) the frequency of transient myocardial ischemia shows a similar increase in the morning, and episodes are often preceded by mental or physical triggers; (3) a ruptured atherosclerotic plaque, often nonobstructive by itself, lies at the base of most coronary thrombi; (4) a number of physiologic processes that could lead to plaque rupture, a hypercoagulable state, or coronary vasoconstriction, are accentuated in the morning; and (5) aspirin and beta-adrenergic blocking agents that affect certain of these processes have been shown to prevent disease onset. The hypothesis presented is that occlusive coronary thrombosis occurs when (1) an atherosclerotic plaque becomes vulnerable to rupture; (2) mental or physical stress causes the plaque to rupture; and (3) increases in coagulability or vasoconstriction, triggered by daily activities, contribute to complete occlusion of the coronary artery lumen. Recognition of the circadian variation--and the possibility of frequent triggering--of the onset of acute disease suggests the need for pharmacologic protection of patients during the vulnerable periods and provides clues to the mechanism of disease onset, the investigation of which may lead to improved methods of prevention.

Advances in thrombolytic therapy

Alteplase and saruplase are more fibrin-specific thrombolytic drugs than anistreplase. These and the thrombolytic drugs of the first generation (streptokinase and urokinase) have shortcomings and limitations. The prolonged intravenous maintenance infusions have been replaced by a bolus injection, accelerated infusions, or the combined intravenous administration of thrombolytic agents. Numerous truncated alteplase or saruplase molecules have been constructed by deletion and domain substitution or hybrids made of the two molecules without gaining in thrombolytic potency. Recombinant staphylokinase and plasminogen activator from bat saliva have some interesting properties and are being investigated. Thrombus-targeted thrombolytic drugs were constructed using monoclonal antibodies against fibrin fragments or against epitopes of activated platelets. Fibrin-specific thrombolytic drugs require the concomitant use of a potent antithrombotic drug to prevent reocclusion. Whether hirudin or synthetic thrombin inhibitors are superior to heparin and whether novel antiplatelet agents, including monoclonal antibodies to platelet receptors and disintegrins, are more effective than aspirin is under clinical investigation. The place of stable analogues of prostacyclin during thrombolytic treatment is still unsettled.

Quantitative and qualitative coronary angiographic analysis: review of methods, utility, and limitations

Coronary angiography continues to be the pivotal study in the diagnosis and treatment of ischemic cardiac disease. Although angiographic equipment and imaging techniques have advanced over the past three decades, the analysis of coronary angiograms, by visual estimated percent diameter stenosis, has remained unchanged in most clinical catheterization laboratories. Rapid, computerized angiographic analysis systems are now available that remedy the inherent imprecision and inaccuracies plaguing visual coronary analysis. Despite its advantages, successful QCA is quite dependent on meticulous attention to radiographic and angiographic technique, even more so than with visual analysis. Although the available QCA systems can reproducibly and accurately define the site and degree of coronary stenosis, they cannot routinely determine whether an obstruction is flow limiting. Several methods, some based on extrapolations of quantitative measures alone, and others based on digital subtraction angiography, have been developed to determine the physiologic impact of a given coronary lesion. Recent observations have demonstrated, however, that even if the physiologic consequences of an obstruction are known, the prognosis of the lesion over time cannot be predicted. The qualitative, morphologic characteristics of a lesion are as, or more, important than the quantitative lesion attributes in determining an atheroma's behavior and stability, and hence, qualitative descriptors should be incorporated into QCA analyses. Although not currently available, future QCA systems will provide, by automated analysis, reproducible and accurate measures of absolute obstruction, physiologic data describing the flow limiting characteristics of a lesion, and qualitative, morphologic lesion descriptors. Implementation of these systems should provide more consistent and accurate prognostic and pathophysiologic information, thereby helping to refine and more effectively direct therapeutic interventions in coronary artery disease.

The underlying coronary lesion in myocardial infarction: implications for coronary angiography

Myocardial infarction is usually caused by sudden thrombotic occlusion of a coronary artery at the site of a fissured atherosclerotic plaque. Recent evidence suggests that coronary angiography may be insensitive in detecting and quantitating atherosclerosis. Serial angiographic studies demonstrate that the majority of myocardial infarctions occur due to occlusion of arteries that previously did not contain angiographically significant (greater than 50%) stenoses. Similarly, quantitative angiography performed after thrombolytic therapy indicates that the coronary lesion underlying the clot is frequently not severely stenotic. Thus, an angiographically apparent stenosis is not necessary for the development of a thrombotic occlusion resulting in an MI. These observations suggest that coronary angiography does not accurately predict the site of a subsequent occlusion that will produce a myocardial infarction.

Angioplasty in ulcerative coronary artery disease: acute results and early follow-up

The safety and efficacy of percutaneous transluminal coronary angioplasty (PTCA) for stenoses involving ulcerative lesions were retrospectively studied. Seventy-seven patients (62 men and 15 women, mean age 62 +/- 10 years) representing 3.4% of 2,250 patients treated with PTCA during the period January 1, 1988 and June 30, 1990, had pre-PTCA stenoses defined as ulcerated. Twenty-eight (36%) of the stenoses were localized in the left anterior descending coronary artery, 9 (12%) in the left circumflex and 40 (52%) in the right coronary artery. During angioplasty, percent diameter stenosis was reduced from 73 +/- 14% to 22 +/- 13% and transstenotic gradient decreased from 48 +/- 18 to 12 +/- 6 mm Hg. Clinical success (freedom from angina at discharge without coronary bypass surgery, infarction or death) was achieved in 70 patients (90.9%). There were seven unsuccessful cases: three underwent elective coronary bypass surgery, one was managed medically, and three developed a major flow interrupting dissection during the procedure requiring emergency coronary bypass surgery. There were no deaths. At mean follow-up of 7.6 months, 45 of 61 patients (73.7%) remained asymptomatic. One patient needed an elective coronary bypass surgery and five patients had a successful repeat PTCA. In conclusion, PTCA for an ulcerated stenosis can be performed safely with a high primary success rate and a favorable early clinical course.

Coronary thrombosis: pathogenesis and clinical manifestations

The majority (greater than 75%) of major coronary thrombi are precipitated by a sudden rupture of the surface of an atherosclerotic plaque (plaque fissuring) causing platelet aggregation where thrombogenic subendothelial tissue has been exposed. Whether the thrombus remains mural and limited, just sealing the rupture, or evolves into an occlusive thrombus seems to depend on: (1) the amount and character of exposed thrombogenic material; (2) the actual thrombotic-thrombolytic equilibrium; and (3) local flow disturbances due to preexisting atherosclerotic stenosis. Thrombus formation may take place within the stenosis, where blood velocity and shear forces are highest, or it may take place or extend poststenotically, where flow separation, recirculation, and turbulence prevail. Platelet aggregation within the stenosis is responsible for the primary flow obstruction, but fibrin subsequently enmeshes the platelets and thus stabilizes the thrombus. Most thrombi have a layered structure, indicating an episodic growth that may alternate with thrombus fragmentation and peripheral embolization: thrombosis and thrombolysis are dynamic processes occurring simultaneously. If the platelet-rich thrombus at the rupture site evolves into an occlusive thrombus, the blood proximal and distal to the occlusion may stagnate and coagulate, giving rise to a secondarily formed red stagnation thrombosis consisting predominantly of erythrocytes held together by fibrin membranes. A ruptured plaque with a dynamic thrombosis superimposed (with or without spasm) seems to underlie the great majority of acute ischemic syndromes: unstable angina, acute infarction, and sudden death. The clinical presentation and the outcome depend on the severity and duration of ischemia: whether the obstruction is occlusive or nonocclusive, transient or persistent--modified by the magnitude of collateral flow.

Reduction of mortality, sudden death and non-fatal reinfarction with beta-adrenergic blockers in survivors of acute myocardial infarction: a new hypothesis regarding the cardioprotective action of beta-adrenergic blockade

Beta-adrenergic blockers have been shown definitely to reduce the incidence of total mortality, cardiovascular mortality, sudden death and nonfatal reinfarction in survivors of an acute myocardial infarction. The mechanisms to explain this protective action of beta blockers have never been elucidated conclusively, and include the antiarrhythmic and myocardial oxygen demand-reducing effects of the drugs. An antithrombotic mechanism has also been suggested. However, beta blockers have relatively weak antiplatelet activity, suggesting that their antithrombotic effects may be related to prevention of coronary artery plaque rupture and the subsequent propagation of an occlusive arterial thrombus rather than direct anticoagulant action. The therapeutic ability of beta blockers to attenuate the hemodynamic consequences of catecholamine surges, may protect a vulnerable atherosclerotic plaque from fracture, thereby reducing risk of coronary thrombosis, myocardial infarction and death.

Frequency of low-grade residual coronary stenosis after thrombolysis during acute myocardial infarction

The clinical, angiographic and demographic characteristics of 42 patients with low-grade (less than 50%) residual stenosis at the infarct lesion after thrombolysis for acute myocardial infarction (MI) were assessed. The study group (group I) represented 21% of 198 consecutive patients receiving thrombolytic therapy over a 59-month period. Data on the 156 remaining patients were pooled for comparison (group II). Group I patients were predominantly men (86%) who were cigarette smokers (81%). Group II patients were predominantly men (75%, p greater than 0.10) but were significantly older (52 +/- 12 vs 56 +/- 10 years, p = 0.02). Prior acute MI or angina was unusual in group I. Sixty percent had no significant (greater than 50%) residual coronary artery disease while 25% had residual single artery disease. Average significant (greater than 50% diameter stenosis) residual vessel disease was 0.6 +/- 1.0 for group I and 1.9 +/- 0.9 for group II (p less than 0.001). In group I, average residual infarct lesion diameter stenosis was 36 +/- 7% in the right anterior oblique and 34 +/- 8% in the left anterior oblique views. Thirty-nine group I patients were discharged with medical therapy and 100% follow-up was obtained over a mean interval of 18 +/- 17 months. Fifteen patients experienced chest pain after acute MI accounting for 17 discrete events. Fifty-nine percent of group I had a benign course on follow-up. Eight events were classified as unstable angina, 4 as acute MI and 5 as atypical angina. Documented coronary vasospasm occurred in 3.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary angiographic ruptured atheromatous plaque as a predictor of future progression of stenosis

To determine whether or not angiographic coronary morphology can predict future development/progression of narrowing, we reviewed coronary angiograms (CAGs) from 29 patients who underwent CAG studies twice but who had no myocardial revascularization during the period of the studies. The mean age of the patients was 52.9 +/- 8.5 years, and the mean interval between the studies was 25.4 +/- 22.6 months. Mean luminal diameter stenosis of 77 lesions that reduced the diameter by 50% or more on either CAG, but were not totally occluded on the initial CAG, increased from 62% to 79% (p less than 0.01). Progression of stenosis developed in 35 lesions (45%); the progression in 13 lesions of the 35 (37%) was on sites associated with no stenosis or mild stenosis on the initial CAG. No relation was found between the development/progression of stenosis and either its initial severity or elapsed time; however, the prevalence of the development/progression of stenosis was more frequent on sites with possible or probable ruptured atheromatous plaque on the initial CAG than on sites without such plaque (p less than 0.05). The evidence suggests that there is no apparent relation between the future development/progression of coronary narrowing and either the severity of stenosis on the initial CAG or elapsed time but that some of the development/progression can be predicted on the basis of certain specific coronary morphology.

Variability of thrombolytic coronary reperfusion: an angiographic study of streptokinase and anistreplase

A total of 1,615 angiographic readings in 240 patients with acute myocardial infarction were analyzed from a randomized trial of intravenous anistreplase (Eminase), also known as anisoylated plasminogen streptokinase activator complex (APSAC), versus intracoronary streptokinase. Coronary arteriography was performed at baseline and at 15, 30, 45, 60, 75, and 90 minutes after drug infusion. Coronary flow in the infarct-related artery was defined using the TIMI criteria. Some serial change in perfusion was noted in 25% of the total patient population and in 49% of all reperfusion patients. Complete loss of perfusion (grade 2 or 3 to grade 0 or 1) occurred in 35% of all reperfused patients. Half of these patients ultimately developed complete loss of perfusion at the study endpoint. All of these changes in flow were statistically more common for the circumflex coronary artery and early treatment (less than 4 h), but did not differ for anistreplase or streptokinase. We conclude that frequent alterations in coronary blood flow occur early during reperfusion therapy and that these findings may explain reports with varying results of thrombolytic therapy. Any angiographic assessment of thrombolytic drug efficacy should take these variations as well as interobserver variability into account.

New approaches to treatment of myocardial infarction

Survival of patients with acute transmural infarction is largely related to the size of the myocardial infarction. The goal of thrombolytic therapy in acute myocardial infarction is maximal salvage of myocardium by reestablishment of flow in the occluded infarct-related artery and the establishment and maintenance of a patent infarct-related artery. Results of randomized trials show a significant reduction in mortality in patients who have undergone thrombolysis. A patent infarct-related artery, even in the absence of a change in left ventricular function, is associated with reduced mortality. The Thrombolysis in Myocardial Infarction Trial and the European Cooperative Trial showed that recombinant tissue-type plasminogen activator is superior to streptokinase in reestablishing flow in a totally occluded artery. Experimental and clinical evidence suggests that thrombolysis and thrombosis occur simultaneously, and that lysis appears to increase both thrombin and platelet activity. Effective reduction of thrombosis accelerates thrombolysis. Rethrombosis after thrombolysis is due to anchored residual thrombus, which alters the hemorrheology of blood flow and produces a highly thrombogenic substrate that is largely due to residual fibrin-bound thrombin. Platelet deposition is directly related to severity of residual stenosis and shear rate. Thrombin appears to be the most potent of the 5 potential stimulators of platelet activation during arterial thrombosis. Proper anticoagulation can play an important role in reducing thrombosis. Experimental evidence strongly supports the use of heparin during and after thrombolysis. A recently reported study shows continued reduction of residual stenosis after 1 month of vigorous anticoagulation with intravenous heparin and subsequent oral anticoagulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Successful and unsuccessful coronary thrombolysis

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Circadian variation and triggers of onset of acute cardiovascular disease

Information obtained during the past decade suggests the need to reexamine the possibility that the onset of myocardial infarction and sudden cardiac death is frequently triggered by daily activities. The importance of physical or mental stress in triggering onset of coronary thrombosis is supported by the findings that 1) the frequencies of onset of myocardial infarction, sudden cardiac death, and stroke show marked circadian variations with parallel increases in the period from 6:00 AM to noon, 2) transient myocardial ischemia shows a similar morning increase, and episodes are often preceded by mental or physical triggers, 3) a ruptured atherosclerotic plaque, often nonobstructive by itself, lies at the base of most coronary thrombi, 4) a number of physiologic processes that could lead to plaque rupture, a hypercoagulable state or coronary vasoconstriction, are accentuated in the morning, and 5) aspirin and beta-adrenergic blocking agents, which block certain of these processes, have been shown to prevent disease onset. The hypothesis is presented that occlusive coronary thrombosis occurs when 1) an atherosclerotic plaque becomes vulnerable to rupture, 2) mental or physical stress causes the plaque to rupture, and 3) increases in coagulability or vasoconstriction, triggered by daily activities, contribute to complete occlusion of the coronary artery lumen. Recognition of the circadian variation--and the possibility of frequent triggering--of onset of acute disease suggests the need for pharmacologic protection of patients during vulnerable periods, and provides clues to mechanism, the investigations of which may lead to improved methods of prevention.