Non surgical coronary artery recanalization in acute transmural myocardial infarction

Reduced In-Hospital Mortality Following Intracoronary Streptokinase Treatment of Acute Myocardial Infarction

Reduced short-term mortality following thrombolytic treatment of acute myocardial infarction has been reported by earlier studies. This study was per formed to compare data from our institution with such results.

From January, 1984, through January, 1986, a total of 628 consecutive pa tients were admitted with acute myocardial infarction. Ninety-one patients (Group A) underwent intracoronary streptokinase (IC-SK) infusion to the in farct-related vessel with a total dose of 440,000 units. The average timing for this intervention from the onset of chest pain was 4.1 ±2.7 hours. Successful recanalization was achieved in 71 of 91 patients (78%). Patients seventy-five years of age or older were not offered IC-SK infusion. In this group, most candidates suitable for coronary angioplasty or bypass surgery had the proce dure within the same hospital admission. The remaining 537 patients (Group B) underwent conventional medical therapy during their hospitalization.

In-hospital mortality for Group A was reported in 4 of 91 patients (4.4%) versus 100 of 537 patients (18.6%) from Group B. These results seem to con form with earlier data that indicate a reduced short-term in-hospital mortality from acute myocardial infarction following IC-SK treatment. Besides recanali zation, this beneficial effect in Group A could also be attributed to earlier inter ventions by revascularization procedures in the majority of patients after recognition of the extent of their coronary artery disease.

Analytic Review: Thrombolytic Therapy in Acute Myocardial Infarction

The salvage of myocardium in the setting of acute myocardial infarction has long been a goal of physicians involved in the care of patients with coronary artery disease. Understanding the role of thrombosis in the pathogenesis of acute myocardial infarction has led the way to an entirely new approach to the treatment of this entity. Thrombolytic therapy has now become a widely used form of treatment with encouraging results. Both intravenous and intracoronary administration of thrombolytic agents have been shown to promote recanalization of acutely occluded coronary arteries. Results of studies using the clot-specific agent, tissue plasminogen activator, intravenously have been most encouraging; successful reperfusion has been obtained in approximately 70% of patients treated. In addition, a recent large-scale trial has shown a reduction in morbidity and mortality with the early use of thrombolytic agents.

Ongoing trials should help delineate the precise role and timing of these agents as the initial form of therapy for acute myocardial infarction. Other issues that remain unresolved are the frequency of restenosis and the role of percutaneous transluminal coronary angioplasty in addition to thrombolytic therapy in the treatment of acute myocardial infarction.

Effect of very early intravenous streptokinase infusion in patients with evolving myocardial infarction

The effect of very early infusion of 1.5 X 10(6) U of streptokinase intravenously was studied in 29 patients with nitroglycerin-resistant chest pain and ST-segment elevation. Infarct size was estimated from maximal LD1 isoenzyme levels, and the diagnosis confirmed by CK-MB determination. Thrombolytic therapy was started within 1 hour of pain onset in 11 patients (group A), between 1 and 2 hours in 10 (group B), and later than 2 hours in eight patients (group C). Marked differences appeared between the groups. Thus, three patients in group A and one patient in group B did not develop infarction, all had critical LAD stenoses. Three patients in group C died in shock without bleeding. Further, the average maximal LD1 values in the 22 patients who survived their infarction differed significantly between the groups, and were 12.6, 19.1 and 36.2 mu kat/l in groups A, B and C, respectively. In conclusion, very early intravenous streptokinase infusion probably reduces myocardial necrosis, and possible prevents infarction in some patients.

Intracoronary Verapamil Rapidly Terminates Reperfusion Tachyarrhythmias in Acute Myocardial Infarction

BACKGROUND

The restoration of coronary flow after transient ischemia immediately induces life-threatening ventricular tachyarrhythmias. Although most of these arrhythmias disappear spontaneously, some of them induce serious hemodynamic changes. This retrospective study investigates the efficacy of therapy with intracoronary verapamil to terminate reperfusion-induced ventricular tachyarrhythmias in patients with acute myocardial infarction (AMI).

METHODS AND RESULTS

Between February 1992 and February 2003, 390 patients with a diagnosis of AMI were enrolled into the study. All patients received mechanical revascularization therapy within 6 h of onset of symptoms, and 109 patients experienced reperfusion-induced tachyarrhythmias. A subset of these patients was treated with intracoronary verapamil (0.25 to 1.0 mg) to terminate the reperfusion-induced tachyarrhythmia. They were evaluated for immediate termination of the tachyarrhythmias, hemodynamic changes, resumption rates, and major complications. Thirty-one patients (28%) were treated with intracoronary verapamil for the immediate termination of reperfusion-induced ventricular tachyarrhythmias. These tachyarrhythmias included 6 premature ventricular contractions, 19 accelerated idioventricular rhythms, 3 ventricular tachycardias, 2 ventricular fibrillations (VFs), and 1 torsades de pointes. Intracoronary verapamil was effective in rapidly terminating all reperfusion-induced arrhythmias except for VFs. The side effects of treatment included temporary hypotension (two patients) and bradycardia (one patient), although all patients recovered spontaneously. No major complications were induced by the intracoronary use of verapamil, and no resumptions of arrhythmias were documented.

CONCLUSION

Intracoronary administration of verapamil can safely terminate reperfusion-induced ventricular tachyarrhythmias in a rapid manner. However, this effect was not seen for reperfusion-induced VF.

Predicting angiographic distal embolization following percutaneous coronary intervention in patients with acute myocardial infarction

The aim of this study was to investigate the relation between lesion morphology identified by intravascular ultrasound (IVUS) before intervention and angiographic distal embolization after percutaneous coronary intervention (PCI) in patients with acute myocardial infarction (AMI). PCI for AMI has already been established as beneficial therapy, although some complications remain unresolved. Distal embolization is 1 of the important complications of PCI. Recently, some new devices have been developed for the prevention of distal embolization. However, few studies exist that look into the relation between lesion morphology and distal embolization. IVUS was performed safely in 140 consecutive patients with AMI before coronary intervention. No patient received thrombolytic therapy. From the incidence of angiographic distal embolization, patients were divided into 2 groups--an embolization group and a nonembolization group--and clinical background, IVUS, and angiographic information were evaluated. Distal embolization was observed in 12 patients (9%). Peak creatine kinase levels (3,877 +/- 2,285 vs 2,293 +/- 1,792 IU/L, p <0.05) and the incidence of angiographic thrombus (25% vs 5%, p <0.05) and intracoronary mobile mass detected by IVUS (75% vs 16%, p <0.001) were higher for patients in the embolization group. From the multivariate logistic regression analysis, only an intracoronary mobile mass detected by IVUS emerged as a predictor of distal embolization (odds ratio 53, 95% confidence interval 2.7 to 1,040, p <0.01). Patients with an intracoronary mobile mass detected by IVUS are prone to distal embolization after PCI and larger infarction. IVUS imaging before PCI may be useful for determining which patients need a distal protection device.

The use of the electrocardiogram to identify epicardial coronary and tissue reperfusion in acute myocardial infarction

The standard 12-lead electrocardiogram (ECG) gives us crucial information concerning myocardial perfusion and the success of reperfusion therapy for ST elevation acute myocardial infarction. Continuous monitoring has advantages over repeated snapshot recordings. There are four electrocardiographic markers for prediction of the perfusion status of the ischemic myocardium: (1) ST-segment measurements, (2) T-wave configuration, (3) QRS changes, and (4) reperfusion arrhythmias. Complete and stable (> or = 70%) resolution of ST-segment elevation is associated with better outcome and preservation of left ventricular function than partial (30 to 70%) or no (<30%) ST-segment resolution. Early inversion of the T waves after initiation of reperfusion therapy is another marker of myocardial reperfusion and a good prognostic sign. Using standard 12-lead ECG, dynamic changes in Q-wave number, amplitude, and width; R-wave amplitude; and S-wave appearance are detected during reperfusion therapy. However, the significance of these changes has not been clarified. Reperfusion arrhythmias, especially bradycardia and accelerated idioventricular rhythm, are detected occasionally during reperfusion therapy, but the value of reperfusion arrhythmias as a marker of coronary artery patency is still debatable. Dynamic changes in the QRS complexes, ST segments and T waves occur during reperfusion therapy and the days after. Whereas changes in ST-segment amplitude have been extensively studied, the significance of QRS-complex and T-wave changes is less clear, and especially whether changes in the QRS complex and T wave may be complementary and additive to ST-segment monitoring. It has remained unclear whether electrocardiographic signs of reperfusion and reischemia should be used for therapeutic decision making in the clinical setting.

The use of the electrocardiogram to identify epicardial coronary and tissue reperfusion in acute myocardial infarction

The standard 12-lead ECG gives us crucial information concerning myocardial perfusion and the success of reperfusion therapy for ST-elevation acute myocardial infarction. Continuous monitoring has advantages over repeated snapshot recordings. There are four electrocardiographic markers for prediction of the perfusion status of the ischemic myocardium: 1) ST-segment measurements; 2) T-wave configuration; 3) QRS changes; and 4) reperfusion arrhythmias. Complete and stable (> or = 70%) resolution of ST-segment elevation is associated with better outcome and preservation of left ventricular function than partial (30% to 70%) or no (< 30%) ST-segment resolution. Early inversion of the T-waves after initiation of reperfusion therapy is another marker of myocardial reperfusion and a good prognostic sign. Using standard 12-lead ECG, dynamic changes in Q-wave number, amplitude and width, R-wave amplitude and S-wave appearance are detected during reperfusion therapy. However, the significance of these changes have not been clarified. Reperfusion arrhythmias, especially bradycardia and accelerated idioventricular rhythm are detected occasionally during reperfusion therapy, but the value of reperfusion arrhythmias as a marker of coronary artery patency is still debatable. Dynamic changes in the QRS complexes, ST-segments and T-waves occur during reperfusion therapy and the days after. While changes in ST-segment amplitude have been extensively studied, the significance of QRS-complex and T-wave changes are less clear, and especially whether changes in the QRS-complex and T-wave may be complementary and additive to ST-segment monitoring. It has remained unclear whether electrocardiographic signs of reperfusion and re-ischemia should be used for therapeutic decision-making in the clinical setting.

Thrombolysis in Acute Myocardial Infarction Complicated by Cardiogenic Shock

The adverse impact of the development of cardiogenic shock in the setting of acute myocardial infarction was first described by Killip and Kimball in 1967. While the in-hospital mortality rate in patients with myocardial infarction and no evidence of heart failure was only 6%, the mortality rate in those patients who developed cardiogenic shock was 81%. Despite advances in cardiovascular care and therapy since that initial report, including universal institution of cardiac care units, advances in hemodynamic monitoring, new inotropic and vasodilating agents, and even increasing utilization of thrombolytic therapy, the mortality from acute myocardial infarction, when complicated by cardiogenic shock, remains disturbingly high, and cardiogenic shock remains the leading cause of death of hospitalized patients following acute myocardial infarction.The grave prognosis associated with this condition has resulted in increased interest in potential therapeutic interventions, particularly in the area of reperfusion therapy. Several studies suggest that, in contrast to the beneficial effects of thrombolytic therapy in most patient populations suffering acute myocardial infarction, mortality rates are not decreased in those patients with cardiogenic shock at the time of lytic administration. Thrombolytic administration does, however, appear to lead to a modest reduction in the percent of patients with myocardial infarction who will subsequently develop cardiogenic shock during hospitalization.Reperfusion rates with lytic therapy in patients with cardiogenic shock are disappointingly low, in the range of 42-48%, significantly lower than those achieved in patients without cardiogenic shock. These low perfusion rates may, in part, be explained by decreased coronary blood flow and perfusion pressure in patients with left ventricular pump failure.Although promising as adjunctive therapy, it is unclear whether institution of balloon counterpulsation has any long-term benefit in patients with cardiogenic shock treated with thrombolytic therapy. Whether other or additional interventions, such as coronary angioplasty and coronary artery bypass graft (CABG), decrease mortality rates in patients with cardiogenic shock remains to be determined.

Association Between Serial Measures of Systemic Blood Pressure and Early Coronary Arterial Perfusion Status Following Intravenous Thrombolytic Therapy

Background: Systemic hypotension, at times transient while in other instances more prolonged, is common among patients with myocardial infarction (MI). It also is a characteristic feature for patients experiencing either advanced congestive heart failure or cardiogenic shock. In this group of patients, thrombolytic therapy has failed to exert. favorable impact on their high in-hospital mortality. Although it has been postulated that the success of thrombolytic therapy is directly linked to systemic blood pressure' there is little information available in human subjects. Methods and Results: In a University of Massachusetts Thrombolysis Data Bank Study, 127 patients with MI who were given intravenous thrombolytic therapy (tPA or streptokinase) within 6 hours from symptom onset (4.2 +/- 1.5 hours) had serial systemic blood pressure measurements (at the time of hospital arrival, treatment initiation, and every 30 minutes during the thrombolytic infusion) and underwent coronary angiography within 120 minutes of treatment initiation. All patients received intravenous heparin and oral aspirin. By univariate analysis, disastolic blood pressure below 80 mmHg at the time of treatment initiation was associated with a reduced angiographic coronary perfusion grade [Thrombolysis in Myocardial Infarction (TIMI) flow grade; p + 0.02]. A correlation analysis of tPA-treated patients indicated that a greater maximum change in diastolic blood pressure during treatment correlated inversely with coronary perfusion (r +.24, p < 0.05). By multivariate regression analysis, however, only shorter time to treatment (p + 0.001) and thrombolysis with tPA (p + 0.02) were independent predictors of coronary arterial perfusion grade. Conclusion: Systemic blood pressure (and presumably proximal coronary arterial perfusion pressure) in the ranges investigated in this study is not an independent predictor of coronary reperfusion following intravenous thrombolytic therapy with either tPA or streptokinase. It seems likely, therefore, that properties intrinsic to the ruptured plaque and occlusive thrombus, and potentially the local metabolic environment, either alone or acting synergistically with perfusion pressure, are determinants of thrombolytic success. Further investigation of factors influencing the efficacy of thrombolysis should be undertaken.

Lesão pulmonar de reperfusão

A lesão de isquemia-reperfusão constitui-se em um evento fisiopatológico comum a diversas doenças da prática clínica diária. O pulmão pode ser alvo da lesão de isquemia-reperfusão diretamente, como no edema pulmonar após transplante ou na resolução de tromboembolismo; ou ainda ser atingido à distância, como nos casos de choque ou por lesão de reperfusão em intestino ou em membros inferiores, como ocorre no pinçamento da aorta, utilizado nas cirurgias de aneurisma. Dentre os mediadores envolvidos na lesão de isquemia-reperfusão, foram identificados espécies reativas tóxicas de oxigênio (ERTO), mediadores lipídicos, como a tromboxana, moléculas de adesão em neutrófilos e endotélio, fator de necrose tumoral, dentre outros. As medidas terapêuticas para a lesão de reperfusão ainda são utilizadas no plano experimental e em poucos estudos clínicos. São utilizados: antioxidantes, bloqueadores de mediadores lipídicos, inibidores da interação entre leucócito e endotélio ou substâncias que favoreçam o fluxo sanguíneo pós-isquêmico.

Emergency primary coronary angioplasty in patients with acute myocardial infarction who are unsuitable for intravenous thrombolysis

Intravenous thrombolytic therapy is now accepted as the standard method of achieving coronary reperfusion in patients with acute myocardial infarction. There are several important limitations. Primary percutaneous transluminal coronary angioplasty is an attractive method for reopening occluded coronary arteries. Between 1986 and 1993, 14 patients in whom there was an absolute contraindication to thrombolysis underwent emergency coronary angioplasty as the primary treatment for acute myocardial infarction. Coronary artery patency was restored in 13/14 (93%). One patient died in hospital. The median follow-up was one year. One patient suffered a further myocardial infarction and one patient required coronary artery bypass surgery at follow-up. Emergency coronary angioplasty services should be developed to treat those patients in whom there is a contraindication to thromboloysis.

Early and 1-year survival rates in acute myocardial infarction complicated by cardiogenic shock: a retrospective study comparing coronary angioplasty with medical treatment

Cardiogenic shock remains a frequently lethal complication of acute myocardial infarction. Early revascularization of the infarct-related artery by coronary angioplasty has been suggested to significantly improve patient survival. In-hospital and 1-year survival was assessed in 50 patients hospitalized for acute myocardial infarction complicated by cardiogenic shock. All patients received medical treatment and intraaortic balloon pump support. Thirty-three patients underwent coronary angioplasty (PTCA group), while 17 patients remained on conventional therapy (no PTCA group). The two groups were comparable for all baseline characteristics. Survival was significantly better in the PTCA group than in the no PTCA group: 64% versus 24% in-hospital survival (p = 0.007) and 52% versus 12% at 1 year (p = 0.006). When angioplasty was successful in achieving reperfusion, survival was further enhanced: in-hospital survival rate was 76% versus 25% in patients with unsuccessful angioplasty and 60% versus 25% at 1 year.

The history of interventional cardiology: cardiac catheterization, angioplasty, and related interventions

The histories of cardiac catheterization, angioplasty, and other catheter interventions are spectacular journeys marked by undeterred genius, serendipity, and the vindication of the scientific method. Cardiac catheterization began with Hales's 1711 equine biventricular catheterization, other early experimental catheterizations in the nineteenth century, and Forssmann's dramatic 1929 right-heart self-catheterization. Cournand, Richards, and others finished unlocking the right heart in the 1940s; Zimmerman, Cope, Ross, and others unlocked the left heart in the 1950s; and the coronary arteries were inadvertently unlocked by Sones in 1958, leading to the advent of percutaneous femoral coronary angiography by Judkins and by Amplatz in 1967. Dotter's accidental catheter recanalization of a peripheral artery in 1963 ushered in the era of intervention, crowned by Gruentzig's balloon angioplasty in the mid-1970s and leading to today's panoply of devices used percutaneously to revascularize the coronary arteries in a variety of clinical settings.

A novel modified tissue-type plasminogen activator (t-PA), E6010, gradually increases coronary blood flow after thrombolysis compared with native t-PA, urokinase and balloon catheter occlusion-reperfusion

In a canine copper coil-induced coronary thrombosis model, the differences in frequency of reperfusion arrhythmias (premature ventricular complexes: PVC) and mortality rate after thrombolysis by intravenous bolus injection of a novel modified tissue-type plasminogen activator (t-PA), E6010, and by continuous intravenous infusion of native t-PA or urokinase were evaluated. Rapid coronary occlusion and reperfusion were produced with a balloon catheter in another group of dogs, and the findings were compared with those in the thrombolysis groups. Reperfusion occurred gradually after the administration of E6010, but was significantly more rapid after administration of native t-PA and urokinase (P < 0.05). PVC were observed more frequently in native t-PA, urokinase and balloon occlusion-reperfusion groups than in the E6010 group. The mortality rate due to ventricular fibrillation was 0.0% in the E6010 group, 50.0% in the native t-PA and balloon occlusion-reperfusion groups, and 33.3% in the urokinase group. These results suggest that the more gradual reperfusion of the coronary artery at an earlier period after drug administration led to the lower frequency of reperfusion arrhythmias and low mortality rate in the E6010 group than in the native t-PA, urokinase and balloon occlusion-reperfusion groups.

Early T wave inversion after thrombolytic therapy predicts better coronary perfusion: clinical and angiographic study

OBJECTIVES

This study was undertaken to test the hypothesis that early inversion of T waves after thrombolytic therapy for acute myocardial infarction predicts patency of the infarct-related artery with high Thrombolysis in Myocardial Infarction (TIMI) perfusion flow and better in-hospital outcome.

BACKGROUND

Although numerous studies have demonstrated a strong association between early resolution of ST segment elevation after acute myocardial infarction and successful thrombolysis, little is known about early changes in T waves after thrombolytic therapy.

METHODS

Ninety-four consecutive patients with acute myocardial infarction treated with recombinant tissue-type plasminogen activator (rt-PA) were studied with admission and predischarge radionuclide ventriculography and with coronary angiography within 72 h of admission. Patient stratification was based on the presence or absence of early (within 24 h) T wave inversion.

RESULTS

Early T wave inversion was associated with a higher patency rate of the infarct-related artery (90% vs. 65%, p < 0.02) and less severe residual stenosis ([mean +/- SD] 73 +/- 27 vs. 83 +/- 22, p = 0.06), and when only TIMI perfusion grade 3 was considered, the difference was even greater (77% vs. 41%, p < 0.001). Patients with early inversion of T waves had a lower peak creatine kinase value ([mean +/- SD] 678 +/- 480 vs. 1,076 +/- 620, p < 0.01), and although a similar percent of patients with and without early T wave inversion had a normal ejection fraction (> or = 55%) on admission, a higher percent of patients with early inversion had a normal ejection fraction at hospital discharge (71% vs. 44%, p < 0.03). Early T wave inversion anticipated a more benign in-hospital clinical course with a lower incidence of adverse cardiac events (10% vs. 33%, p < 0.02).

CONCLUSIONS

Early inversion of T waves in patients with acute myocardial infarction treated with thrombolytic therapy suggests patency of the infarct-related artery, better perfusion grade and left ventricular function and a more benign in-hospital course.

Protection from reperfusion-induced arrhythmias by polyethylene glycol 600

The effects of polyethylene glycol (PEG) 600 on cardiovascular parameters and reperfusion-induced arrhythmias were investigated using a 5-min period of ligation of the left anterior descending coronary artery followed by reperfusion in an anaesthetized open-chest rat model. PEG 600 was effective in reducing reperfusion arrhythmias, such as ventricular fibrillation and ventricular tachycardia. Mortality was decreased from 29.4% (5/17) in the saline-control to 0% (0/14) in the PEG-treated group (P < 0.05). Biochemical investigations during the ischaemia/reperfusion period revealed that PEG infusion resulted in a reduction of cardiac lactate as well as a striking maintenance of the glutathione content of the heart.

Incidence and significance of ventricular tachycardia and fibrillation in the absence of hypotension or heart failure in acute myocardial infarction treated with recombinant tissue-type plasminogen activator: results from the Thrombolysis in Myocardial Infarction (TIMI) Phase II trial

OBJECTIVES

The purpose of this study was to determine the incidence of ventricular tachycardia and fibrillation without hypotension or heart failure after treatment with recombinant tissue-type plasminogen activator (rt-PA), anatomic correlates of their development, the effect of immediate intravenous metoprolol on their occurrence and the outcome of patients with these arrhythmias.

BACKGROUND

Malignant arrhythmias after thrombolytic therapy have been reported to occur as a result of coronary reperfusion, which is associated with reduced mortality in patients receiving thrombolytic therapy.

METHODS

We analyzed data from 2,546 patients in the Thrombolysis in Myocardial Infarction (TIMI) Phase II trial without congestive heart failure or hypotension during the 1st 24 h after study entry. Forty-nine patients (1.9%) developed sustained ventricular tachycardia or ventricular fibrillation within 24 h of study entry (group 1), and 2,497 patients (98.1%) did not (group 2).

RESULTS

Baseline characteristics and admission laboratory values were similar in the two groups. In patients undergoing protocol angiography 18 to 48 h after rt-PA, the infarct-related artery was patient in a greater percent of group 2 patients (87% [1,015 of 1,169]) than group 1 patients (68% [15 of 22], p = 0.01), although angiography was performed less frequently in group 1 than in group 2. More group 1 than group 2 patients died within 21 days (20.4%) (1.6%, p < 0.001). For patients surviving to 21 days, there was no difference in mortality between patients in the two groups in the following year.

CONCLUSIONS

Ventricular tachycardia and fibrillation are not markers for reperfusion after thrombolytic therapy. These arrhythmias are associated with occlusion, not patency, of the infarct-related artery. Early mortality is increased in patients who develop ventricular tachycardia and fibrillation, even in the absence of congestive heart failure and hypotension.

Emergency coronary angioplasty for acute myocardial infarction: predictors of early occlusion of the infarct-related artery after balloon inflation

THE FACTORS RESPONSIBLE FOR EARLY OCCLUSION OF THE INFARCT VESSEL AFTER emergency percutaneous transluminal coronary angioplasty (PTCA) were retrospectively examined in 191 patients with acute myocardial infarction. During the 24-hour period after the initial balloon inflation, 47 patients (25%) had occlusion of the vessel (occlusion group), whereas 144 did not (nonocclusion group). The former patients immediately underwent repeat PTCA, which was successful in 37. Univariate correlates of early occlusion were a shorter time interval between the onset of symptoms and PTCA (3.5 +/- 2.2 vs 4.5 +/- 2.9 hours, p = 0.025), right coronary artery involvement (53% vs 30%, p = 0.015), prior thrombolytic therapy (49% vs 32%, p = 0.035), and undersized inflation (43% vs 17%, p < 0.001). With multivariate analysis the three independent predictors were undersized inflation (p < 0.001), right coronary artery involvement (p = 0.004), and a shorter time interval until PTCA (p = 0.011). Thus patients undergoing early PTCA and having right coronary artery involvement appear to be at greater risk of having early occlusion. Thrombolytic agents and undersized inflation may also play an important role in its development.

Hemodynamic, mechanical, and metabolic determinants of thrombolytic efficacy: a theoretic framework for assessing the limitations of thrombolysis in patients with cardiogenic shock

Although thrombolytic therapy has been shown to limit infarct size, preserve left ventricular function, and improve survival in most subgroups of patients with acute MI, a benefit has not been demonstrated in patients with clinical left ventricular dysfunction or overt cardiogenic shock before treatment is initiated. The reason(s) for the lack of benefit derived from thrombolytic therapy in these settings is unclear. Left ventricular dysfunction and overt cardiogenic shock are the result of extensive myocardial necrosis, typically in excess of 30% of the left ventricle, which progresses over time. The available data suggest that thrombolytic efficacy is decreased because of either hemodynamic, mechanical, or metabolic factors. As a result coronary patency is rarely achieved in a timely fashion, and if patency is achieved it typically is not maintained. The ability of mechanical revascularization by means of balloon angioplasty to reduce mortality suggests that reperfusion is a key determinant of outcome even among patients with large infarctions and early signs of left ventricular dysfunction. Thrombolytic therapy, which is widely available and extensively tested, represents the standard of care for patients with acute MI. Its apparent lack of efficacy in patients with congestive heart failure and cardiogenic shock is poorly understood. Further investigation must therefore be undertaken.

Effects of tissue plasminogen activator therapy on the frequency of acute right ventricular myocardial infarction associated with acute left ventricular infarction

To assess the effects of reperfusion therapy on acute right ventricular myocardial infarction, we studied at necropsy the hearts from 51 patients who died after receiving intravenous recombinant tissue plasminogen activator for acute left ventricular myocardial infarction as part of the Thrombolysis in Myocardial Infarction (TIMI) study. Right ventricular infarction occurred in none of 29 patients with infarction of the anterior wall of the left ventricle and in 8 of 22 patients (36%) with infarction of the posterior (inferior) wall of the left ventricle. Of the 22 patients with posterior wall infarction, the 8 patients with right ventricular infarction were compared to the 14 patients without right ventricular infarction. The patients with right ventricular infarction had a longer mean interval from tissue plasminogen activator infusion to peak creatine phosphokinase level (19 vs. 11 h, P < 0.03), a lower frequency of hemorrhagic necrosis (2 of 8 vs. 10 of 14, P < 0.04) and higher frequency of luminal thrombus in the infarct-related coronary artery (6 of 8 vs. 3 of 14, P = 0.054). Each of these findings is associated with the absence of coronary reperfusion. Thus, successful reperfusion following acute left ventricular myocardial infarction appears to be associated with a decreased frequency of concomitant right ventricular myocardial infarction.

Use of twenty-four hour infusions of intracoronary tissue plasminogen activator to increase the application of coronary angioplasty

Coronary arteries occluded by long lengths of thrombus are usually considered unattractive for angioplasty. Nine patients (8 male, mean age 50.1 years) undergoing angiography for unstable angina were found to have single vessel disease considered unsuitable for angioplasty as the vessel was occluded by a long length of thrombus. These patients were treated with 24 hr intracoronary infusions of 100 mg tPA in an attempt to make angioplasty feasible. Marked thrombolysis occurred in 7 patients who received uncomplicated infusions. One case was unsuccessful due to catheter displacement, while another had the infusion ceased due to an intracerebral bleed from a previously silent A-V malformation. This was the only major complication. Angioplasty was attempted in 6 of 7 cases where lysis had been achieved, with success in all lesions attempted. This reports shows that intracoronary tPA infused over prolonged periods produces excellent thrombolysis, making angioplasty feasible in some patients who were previously unsuitable.

Effects of aspirin on coronary reocclusion and recurrent ischemia after thrombolysis: a meta-analysis

Reocclusion of infarct-related coronary arteries within 2 weeks of thrombolytic therapy varies from 5% to 45% and neither clinical nor angiographic variables have been proved to be predictive of reocclusion. The goal of the present study was to evaluate whether aspirin could prevent coronary reocclusion and recurrent ischemia after thrombolysis. For this purpose, a meta-analysis including 32 studies was performed. Although the studies showed very similar demographic data, the reocclusion rate assessed by angiography in 419 patients treated with aspirin was 11% compared with 25% in 513 patients without aspirin therapy (p less than 0.001). Recurrent ischemic events were present in 25% of 2,977 patients treated with aspirin and 41% of 721 patients treated without aspirin (p less than 0.001). The effect of aspirin was similar in trials with either streptokinase or recombinant tissue-type plasminogen activator (rt-PA). Thus, aspirin in the presence of heparin might prevent coronary reocclusion after thrombolysis.

Limitations of thrombolytic therapy for acute myocardial infarction complicated by congestive heart failure and cardiogenic shock

As many as one quarter of patients treated with thrombolytic therapy present with congestive heart failure or cardiogenic shock. Although thrombolytic therapy has been shown to limit infarct size, preserve left ventricular ejection fraction and decrease mortality in most subgroups of patients, no apparent benefit has been demonstrated in patients with clinical left ventricular dysfunction. The lack of correlation between ejection fraction and other measurements of left ventricular dysfunction such as exercise time, cardiac output, filling pressures, activation of the neurohumoral system and regional perfusion bed abnormalities may partly explain this paradox. Alternatively, lower perfusion rates, higher reocclusion rates, associated mechanical complications or completed infarction may explain these findings. Preliminary data indicate that emergency coronary angioplasty or bypass graft surgery improves survival in selected patients with cardiogenic shock. Because these findings suggest that restoration of infarct artery patency is especially important in patients with clinical left ventricular dysfunction, additional studies are needed in these patients to investigate the potential benefit that new thrombolytic strategies, inotropic or vasodilator agents or intraaortic balloon counterpulsation might offer by augmenting coronary blood flow and improving reperfusion rates. Currently, acute mechanical revascularization should be considered for patients who present with congestive heart failure associated with hypotension or tachycardia and for patients with cardiogenic shock.

Dipyridamole echocardiography test. A new tool for detecting jeopardized myocardium after thrombolytic therapy

BACKGROUND

We wished to assess whether dipyridamole echocardiography test (DET) can detect jeopardized myocardium after thrombolytic therapy.

METHODS AND RESULTS

Seventy-six consecutive patients with a first acute myocardial infarction (AMI) were treated with 2 million IU urokinase i.v. within 4 hours of the onset of AMI and underwent high-dose (as much as 0.84 mg/kg over 10 minutes) DET 8-10 days after AMI. The results were correlated to the anatomy of the infarct-related vessel (IRV). In patients with positive DET, we evaluated the wall motion score index (WMSI; a semiquantitative integrated estimation of extent and severity of the stress-induced dyssynergy). WMSI was derived by summation of individual segment scores divided by the number of interpreted segments. In a 13-segment model, each segment was assigned a score ranging from 1 (normal) to 4 (dyskinetic). Fifty-three patients had positive results on DET. Of these, 42 had dipyridamole-induced new wall motion abnormalities (WMAs) confined to the infarct zone or adjacent segments. In these patients, mean WMSI increased from 1.46 +/- 0.26 (at resting conditions) to 1.73 +/- 0.35 (at peak dipyridamole) (p less than 0.01), whereas no significant change was detected in negative patients (1.6 +/- 0.34 versus 1.57 +/- 0.34, p = NS). Coronary angiography showed a patent IRV (TIMI grade 2 or 3) in 53 patients and no or minimal reperfusion (TIMI grade 0 or 1) in 23 patients. A patent IRV with critical residual stenosis was found in 35 of 42 patients with dipyridamole-induced WMAs in the infarct zone and in 18 of 34 patients without WMAs (p less than 0.05). Among the 23 patients with occluded IRVs, nine had collateral flow to the distal vessel; six of these had a positive DET. Thus, the sensitivity and specificity for identifying a critically stenotic but patent IRV or the presence of a collateral-dependent zone were 66% and 93%, respectively. In a subset of nine patients with a positive DET in the infarct zone or adjacent segments, DET and a control coronary angiography were repeated 1-3 months after an angiographically successful (residual stenosis, 50% or less) coronary angioplasty in the IRV. The repeat DET was negative in eight patients (all with patent IRV at control angiography) and again positive in one patient, who showed restenosis at angiography. The WMSI, at resting conditions was similar before and after angioplasty, whereas it differed significantly at peak dipyridamole (1.7 +/- 0.2 versus 1.4 +/- 0.2, p less than 0.01).

CONCLUSIONS

DET can identify the anatomy of the IRV, and dipyridamole-induced WMAs within the infarct zone detect regions with jeopardized myocardium that may benefit from intervention.

Comparison of intravenous urokinase plus heparin versus heparin alone in acute myocardial infarction. Urochinasi per via Sistemica nell'Infarto Miocardico (USIM) Collaborative Group

In a randomized trial of the effects on in-hospital mortality of intravenous urokinase plus heparin versus heparin alone, 2,531 patients with acute myocardial infarction in 89 coronary care units were enrolled for greater than 30 months. Patients admitted within 4 hours of the onset of pain were randomized to receive either intravenous urokinase (a bolus dose of 1 million U repeated after 60 minutes) plus heparin (a bolus dose of 10,000 U followed by 1,000 IU/hour for 48 hours) or heparin alone (infused at the same rate). Complete data were obtained in 2,201 patients (1,128 taking urokinase and 1,073 taking heparin). At 16 days, overall hospital mortality was 8% in the urokinase and 8.3% in the heparin group (p = not significant). Among patients with anterior infarction, mortality was 10.3% in the urokinase and 13.9% in the heparin group (p = 0.09; relative risk = 0.73). The incidence of major bleeding (urokinase 0.44%, heparin 0.37%) as well as the overall incidence of stroke (urokinase 0.35%, heparin 0.20%) was similar in the 2 groups. The rates of major in-hospital cardiac complications (reinfarction, postinfarction angina) were also similar.

Acute effects of delayed reperfusion on myocardial infarct shape and left ventricular volume: a potential mechanism of additional benefits from thrombolytic therapy

The purpose of this study was to characterize the effects of late reperfusion on myocardial infarct shape and to quantitate associated changes in left ventricular volume. Reperfusion was delayed until there was no salvage of ischemic myocardium. Dogs underwent 6.5 h of left anterior descending coronary artery occlusion (n = 5) or 5.5 h of occlusion and 1 h of reperfusion (n = 5). Infarct shape was measured with pairs of ultrasonic crystals implanted circumferentially in the mid myocardium. Infarct stiffness was determined from end-diastolic pressure-segment length curves produced by aortic clamping. Left ventricular volume was measured with three pairs of endocardial ultrasonic crystals and the effect of infarct shape change on left ventricular volume was determined. Infarct size, expressed as a percent of the area at risk, was similar in reperfused (97 +/- 1%) and nonreperfused (98 +/- 1%) hearts. After coronary artery occlusion, infarct segments became akinetic and functional dilation, measured as end-diastolic ultrasonic crystal separation, increased to a similar extent in reperfused (24 +/- 7%) and nonreperfused (19 +/- 3%) hearts. In 13 additional dogs that underwent reperfusion and instrumentation with endocardial ultrasonic crystals for volume measurement, left ventricular volume increased 42 +/- 6% over the preocclusion level (p less than 0.001). Within minutes of reperfusion, the infarct stiffened, infarct dilation decreased to 1 +/- 4% over the baseline preocclusion level (p less than 0.05 vs. prereperfusion) and left ventricular volume decreased to 16 +/- 11% over the baseline level (p less than 0.01 vs. postocclusion). Thus, coronary artery reperfusion reverses initial infarct dilation. Changes in infarct dilation occur immediately after reperfusion and are accompanied by infarct stiffening and a decrease in left ventricular volume. Reperfusion can affect infarct shape and stiffness at a point in time when myocardial salvage is no longer possible.

Noninvasive detection of reperfusion in acute myocardial infarction based on plasma activity of creatine kinase MB subforms

Successful thrombolytic therapy is associated with an accelerated release of creatine kinase (CK) MB from necrotic myocardium. With use of a previously validated assay, the plasma kinetics of the myocardial subform (MB2) and the plasma-modified subform (MB1) were determined in blood samples obtained from 56 patients with acute Q wave myocardial infarction: 33 patients who received thrombolytic therapy (group A) and 23 patients managed conservatively (group B). Plasma MB2 activity increased more rapidly in the group A patients, but there was substantial overlap with group B. Plasma MB1 activity did not differ significantly between the two groups. The MB2/MB1 ratio was significantly higher in group A patients than in group B patients between 2 and 10 h after the onset of infarction. Among group A patients, the ratio increased from 2.4 +/- 1.6 to 4.6 +/- 2.0 in the 1st h after therapy (p less than 0.001). The peak ratio was 6.3 +/- 2.5 in group A patients and 3.1 +/- 1.2 in group B patients. Twenty-seven of the 33 group A patients had a peak ratio greater than 3.8 versus 5 of the 23 group B patients (p less than 0.001). In seven group A patients, the ratio was greater than 3.8 before plasma CK MB activity was out of the normal range. Angiography was performed at 5.0 +/- 3.5 days in 39 patients. Eighteen (90%) of 20 patients with a patent infarct-related artery had a peak ratio greater than 3.8; 17 (89.5%) of 19 patients with an occluded infarct-related artery had a ratio less than 3.8 (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Reperfusion arrhythmias are rare during acute myocardial infarction and thrombolysis in man

Coronary arterial reperfusion is commonly associated, in anaesthetized animals, with severe arrhythmias, but the clinical relevance of this model remains uncertain. Continuous electrocardiographic ST-segment recording was performed immediately from admission in 38 patients who presented within six (mean 2.5) hours of the onset of acute myocardial infarction and had emergency coronary arteriography and thrombolysis with intracoronary streptokinase. All patients received high doses of isosorbide dinitrate but no prophylactic anti-arrhythmic drugs. In 19 patients, 36 occurrences of intermittent reperfusion were observed. Stable reperfusion was achieved in 32 patients. Only 14 episodes of arrhythmia (11 ventricular) were observed in 6 patients within five minutes of transient or stable reperfusion. No episodes of arrhythmia were documented within five minutes of the other 57 occurrences of reperfusion. In contrast, 215 episodes of arrhythmia (198 ventricular) not associated with reperfusion were recorded in 32 patients. Arrhythmias are commonly observed in patients during evolving acute myocardial infarction and thrombolysis but are an insensitive and rarely specific marker of reperfusion at the time when this occurs.

Rapid resolution of ST elevation and prediction of clinical outcome in patients undergoing thrombolysis with alteplase (recombinant tissue-type plasminogen activator): results of the Israeli Study of Early Intervention in Myocardial Infarction

Alteplase (recombinant tissue-type plasminogen activator (rt-PA)) was infused within four hours of onset of symptoms in 286 patients with acute myocardial infarction. Delayed coronary angiography was performed 72 hours after admission with coronary angioplasty if indicated. Electrocardiographic monitoring was continuous during the first hour of treatment. The sum of the ST segment elevations (sigma ST) was calculated on electrocardiograms recorded at entry and an hour later. ST elevations resolved rapidly within one hour of treatment in 189 patients and persisted in 97 patients. Rapid resolution of ST elevation correlated with angiographic coronary patency as determined by coronary angiography 72 hours after admission. The patients with rapid resolution of sigma ST had significantly smaller infarcts and a better clinical outcome than the patients with persistent ST elevation. sigma ST values at entry and one hour after treatment had no additional independent predictive value. Rapid resolution of ST elevations in patients undergoing thrombolysis with alteplase was associated with a significantly smaller release of creatine kinase, better preservation of left ventricular function, lower morbidity, and less short and long term mortality. Rapid resolution of sigma ST elevation is an efficient indicator of clinical outcome in groups of patients with acute myocardial infarction undergoing thrombolysis with alteplase.

Incidence and prognosis of secondary ventricular fibrillation in acute myocardial infarction. Evidence for a protective effect of thrombolytic therapy. GISSI Investigators

The multicenter randomized study of the Gruppo Italiano per lo Studio della Streptochinasi nell'Infarto Miocardico has provided the opportunity to analyze the impact of thrombolytic treatment on secondary ventricular fibrillation incidence in a large population of patients (11,712) with acute myocardial infarction. A reduction of about 20% in the frequency of secondary ventricular fibrillation was observed among patients allocated to thrombolytic treatment (streptokinase, 2.4% versus control, 2.9%; relative risk, 0.80; 95% confidence interval, 0.64-1.00). Streptokinase appeared to exert its protective effect specifically in patients treated within 3 hours of onset of symptoms (streptokinase, 2.6% versus control, 3.7%; relative risk, 0.71; 95% confidence interval, 0.53-0.95). This protection was essentially due to a reduced incidence of late ventricular fibrillation occurring after the first day of hospitalization. The 311 patients with secondary ventricular fibrillation represented an overall incidence of 2.7%. Such incidence was not related to infarct location or sex but was significantly more common in patients older than 65 years (3.3% versus 2.3% in younger patients). A significant excess of in-hospital deaths was found in patients with secondary ventricular fibrillation compared with those in the reference group (38% versus 24%; relative risk, 1.98; 95% confidence interval, 1.56-2.52). Conversely, secondary ventricular fibrillation was not a predictor of 1-year mortality for hospital survivors. Thrombolytic treatment with intravenous streptokinase affords protection against secondary ventricular fibrillation most probably by a limitation of infarct size. When the arrhythmia complicates the course of infarction, it is associated with an adverse short-term outcome, whereas the long-term prognosis is not influenced.

Value of immediate angioplasty after intravenous streptokinase in acute myocardial infarction

To improve reperfusion, immediate percutaneous transluminal coronary angioplasty (PTCA) was considered after intravenous streptokinase (0.75 to 1.5 million U) was administered to 98 patients with acute myocardial infarction less than 4 hours after the onset of chest pain. Thirty-four culprit arteries were occluded (group A); 42 arteries were patent with residual stenosis of more than 70% (group B). Twenty-two patients had residual stenosis of less than 70% (group C); eight of these had severe disease of the remaining vessels. Group C patients were either treated conservatively or underwent bypass surgery. Immediate PTCA was attempted in 74 patients (32 in group A, 42 in group B) and was successful in 68 (92%). Emergency bypass surgery for acute occlusion after PTCA was required in two patients. Follow-up averaged 23 months (range, 16 to 47 months). Asymptomatic occlusion recurred in three patients. Restenosis occurred in five patients: four had early restenosis (one in group A, three in group B) and one had late restenosis (group B). These arteries were successfully redilated. Late reinfarction occurred in two patients. They were treated with intravenous urokinase and repeat PTCA. Elective bypass surgery was performed in three patients because of recurrent angina. They had severe three-vessel disease as revealed by control angiography. The mortality rate was 2.7% (two patients; one in group B had early reinfarction, and one patient in group A died suddenly after 17 months). Eighty-five percent of patients treated with PTCA alone remain free of symptoms. This approach has a high success rate and low morbidity and mortality rates. Long-term results are superior to thrombolysis alone.

Reperfusion therapy in acute myocardial infarction: present status and controversy

Coronary thrombolysis revolutionized the treatment of acute myocardial infarction. Most of the experience was obtained with intravenous use of streptokinase and tissue-type plasminogen activator, the latter being superior to streptokinase in regard to coronary recanalization. Numerous other promising thrombolytic agents are being investigated. Both streptokinase and tissue-type plasminogen activator decreased mortality in large trials; comparison studies in terms of efficacy are presently being performed (GISSI 2). Aspirin is an important adjunct to thrombolytic therapy; it decreased mortality by itself (ISIS 2). Heparin is conventionally used together with thrombolysis. Its efficacy is under study (GISSI 2). Intracranial hemorrhage is the most devastating complication of thrombolysis. With the present dosage regimens, the incidence is approximately 0.5%. Percutaneous transluminal coronary angioplasty in conjunction with thrombolysis accomplished frequent and persistent recanalization of the infarct artery with low mortality, including high risk patients. The TIMI IIB study demonstrated that the results of a "conservative strategy" with aggressive management of recurrent ischemic events were comparable to those of an "invasive strategy." Subgroup analysis should, however, be awaited. High risk patients with low ejection fraction or with shock benefit by early mechanical coronary recanalization. The role of thrombolysis in the "late" stage of transmural myocardial infarction or in the acute ischemic syndrome (unstable angina/non-Q-wave myocardial infarction) is unclear and presently under investigation.

The electrocardiographic diagnosis of acute myocardial infarction in the thrombolytic era

The 12-lead ECG remains a simple and inexpensive technique to diagnose AMI in its early phases. The diagnostic accuracy of the ECG depends upon the extent of myocardial necrosis and its localization. The ECG is most sensitive in patients with occlusion of the LAD artery, followed by the RCA and the left CFA. In 10% to 20% of patients with AMI the initial ECG either shows nonspecific changes or is normal. The correlation between the ECG and infarct-related artery varies according to the involved vessel. Classic ECG changes are seen in 90% of the LAD artery, in 70% to 80% of RCA, and in only 50% of CFA occlusions. A second important issue is the mechanism and clinical significance of reciprocal ST segment changes, which usually indicate larger MI, more impaired ventricular function, worse prognosis, and in some patients, significant disease of a noninfarct-related artery. Furthermore, the value of the ECG in estimating myocardial injury and infarct size remains controversial. The ECG plays an important role in coronary reperfusion. ST segment elevation is one of the principal criteria for instituting thrombolytic therapy, and helps predict those who will most likely benefit from coronary reperfusion. The role of the ECG in evaluating the reperfusion status after coronary thrombolysis is not clear. Rapid return to baseline or normalization of the ST segment suggests opening of the occluded vessel, though a small or negligible change does not exclude successful reperfusion.

Occurrence of oxidative stress during reperfusion of the human heart

We have investigated the relation between occurrence of myocardial oxidative stress and functional recovery during postischemic reperfusion in 20 selected patients subjected to aortocoronary bypass grafting. Patients were selected for having normal percent ejection fraction and left ventricular end-diastolic pressure before the operation. Occurrence of oxidative stress was assessed by measuring the formation and release of oxidized glutathione (GSSG) in the coronary sinus immediately before aortic cross-clamp, 1, 5, 10, and 20 minutes after removal of aortic cross-clamp, and 10 and 20 minutes after the end of cardiopulmonary bypass. Reduced glutathione (GSH), lactate, and creatine phosphokinase release were also monitored with the same timing. Standard hemodynamic measurements were recorded by means of a triple-lumen thermodilution pulmonary artery catheter before sternotomy, 15 minutes after the end of cardiopulmonary bypass, and during the 24 hours after termination of cardiopulmonary bypass. Reperfusion in patients after a short period of ischemia (less than 30 minutes; group 1) resulted in a small and transient release in the coronary sinus of GSSG and GSH and in a progressive improvement of hemodynamic parameters reaching a stable state 4 hours after the operation. In patients with a period of ischemia longer than 30 minutes (group 2), reperfusion induced a marked and sustained release of lactate, GSH, and GSSG; the arteriocoronary sinus difference for GSSG was still negative after the end of cardiopulmonary bypass. The arteriocoronary sinus difference for creatine phosphokinase also remained negative for as long as 20 minutes after cardiopulmonary bypass, and the rate of functional recovery was significantly delayed, reaching the values of group 1 only 12 hours after the operation. In these patients there was a positive correlation (r = 0.88, p less than 0.01) between the duration of ischemia and the myocardial arteriovenous difference for GSSG. In addition, there was a negative correlation between the arteriocoronary sinus difference for GSSG and cardiac index measured 2, 4, and 6 hours after the operation. These data suggest for the first time that, depending on the severity of the ischemic period, oxidative stress occurs during reperfusion of patients with coronary artery disease who are subjected to heart surgery and that it may be linked with a delay in postoperative recovery of cardiac function.

Increased platelet thromboxane A2/prostaglandin H2 receptors in patients with acute myocardial infarction

Platelets have been implicated in the formation of occlusive intracoronary thrombi leading to unstable angina pectoris and acute myocardial infarction. Evidence of platelet involvement in these syndromes includes increased thromboxane A2 synthesis during ischemic events and enhanced in vitro sensitivity to agonists. To determine the density and affinity of platelet thromboxane A2/prostaglandin H2 (TXA2/PGH2) receptors in patients with acute myocardial infarction and unstable angina pectoris, the maximum number of binding sites (Bmax) per platelet and the dissociation constant (Kd) of the TXA2/PGH2 receptor antagonist, [125I]-PTA-OH, was determined at equilibrium in washed platelets. Patients with acute myocardial infarction had a significantly (p = 0.006) higher Bmax (4,468 +/- 672 sites/platelet, n = 9) compared with controls (2,206 +/- 203 sites/platelet, n = 8). Restudied at a time when the patients' coronary artery disease was clinically stable, Bmax values for the myocardial infarction group had returned to within normal limits. The dissociation constant for [125I]-PTA-OH was not significantly different in the acute myocardial infarction patients compared with controls. In patients with acute myocardial infarction, the duration of chest pain was positively correlated (r = 0.71, p less than 0.02) with the number of [125I]-PTA-OH binding sites (Bmax). In vitro platelet sensitivity to the TXA2/PGH2 mimetic, U46619, was assessed in aggregation studies. The maximal velocity of aggregation (slope) correlated with platelet TXA2/PGH2 receptor number (r = 0.67, p less than 0.001) and was significantly higher (p less than 0.02) in the acute myocardial infarction patients compared with the other study groups. There was no significant difference in the aggregation EC50 values for the thromboxane mimetic U46619 between unstable angina, acute myocardial infarction, and control groups.(ABSTRACT TRUNCATED AT 250 WORDS)

[Arrhythmia as an indicator for reperfusion following acute myocardial infarct?]

For the purposes of the European double blind and randomized study 27 patients with acute myocardial infarction underwent thrombolysis with rt-PA (60 mg over 90 minutes i.v.) or placebo. To evaluate whether arrhythmias, especially ventricular arrhythmias indicate coronary reperfusion after thrombolysis a 24 hour Holter monitoring was performed from the beginning of the rt-PA or placebo infusion. Typical reperfusion arrhythmias were thought to be idioventricular rhythms (rate less than 110/min), ventricular tachycardia (rate greater than 110/min) or bradycardic rhythm disturbances (rate less than 50/min). The effect of thrombolysis on reperfusion of the infarct related artery was evaluated 90 minutes after the infusion by coronary angiography. After 90 minutes of rt-PA or placebo infusion in 16/16 patients treated with rt-PA and 2/11 patients, who received placebo, was the infarct artery patent. 16/18 patients with a patent artery presented a total of 105 arrhythmic events. 47% of the arrhythmias obviously due to reperfusion were classified as idioventricular rhythms. In contrast only 3/9 patients with an occluded infarct artery presented 25 arrhythmic events. The time of occurrence was not different during the running rt-PA infusion compared to placebo. The following interval up to 24 hours showed no difference in incidence and type of the arrhythmias. No relationship was found between reperfusion arrhythmias and salvage of myocardium during 90 minutes of rt-PA or placebo infusion.

Clinical and laboratory signs of reperfusion: are they reliable?

We studied 101 patients (88 men and 13 women, mean age 54.5 +/- 10 years) who arrived at the hospital during the first 6 hours of acute myocardial infarction evolution. Our objective was to assess the reliability of clinical and laboratory signs of recanalization using intravenous streptokinase as a thrombolytic agent. The mean time between the beginning of infusion and coronary arteriography was 53.83 +/- 43 hours. The positive predictive values for pain, arrhythmia, ST segment and enzymes were 97.9%, 94.2%, 91.8% and 90.8%, respectively; the negative predictive values were 46.8%, 40.8%, 37.2%, and 50% in the same order. Sensitivity was 65.7%, 62.8%, 58.4% and 77.6% and specificity 95.6%, 86.9%, 82.6% and 73.9%, respectively. The positive predictive value, calculated on the basis of the presence of each variable alone or in association showed a probability of recanalization of 76.9% for one sign, 84% for two, 96.3% for three and 100% for all four. When we compared the positive predictive values of each variable according to the interval between the beginning of pain and admission to the hospital (during the first 3 hours or between 3 and 6 hours) our results were 100%/94% for pain (P = NS), 97%/88% for arrhythmia (P = NS), 100%/75% for ST segment (P = 0.004), and 97%/80% for enzymes (P = 0.019). The same analysis applied to negative predictive values showing 22%/62% (P = 0.007), 17%/55% (P = 0.008), 21%/47% (P = NS), 27%/61% (P = NS) for pain, arrhythmia, ST segment and enzymes, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiographic morphology of coronary artery stenoses in prolonged rest angina: evidence of intracoronary thrombosis

Previous clinical and angiographic/histopathologic correlative studies have demonstrated that angiographic findings of occlusive thrombus, intraluminal filling defects and complex lesion morphology indicate the presence of intracoronary thrombosis. The purpose of this study was to determine whether the presence of these descriptors of intracoronary thrombosis is associated with the syndrome of prolonged rest angina. The coronary angiograms of 50 patients with prolonged rest angina without myocardial infarction (group I) and 42 concurrent patients with stable angina (group II) were reviewed without knowledge of the clinical syndrome. Patients with prior myocardial infarction, coronary angioplasty or coronary artery bypass graft surgery were excluded, as were patients with important aortic stenosis. Each coronary artery stenosis in a major epicardial vessel was evaluated for the presence or absence of intracoronary thrombus (defined using standard criteria), complex lesion morphology (defined as the presence of haziness, a smudged appearance or irregular lesion margins) and eccentricity, and the frequency of each of these findings in groups I and II was compared. Intracoronary thrombus was present significantly more often in group I patients (42%) than in group II patients (17%) (chi 2 5.77; p less than 0.02). Complex lesion morphology was also present significantly more often in group I (44%) than in group II (14%) patients (chi 2 8.17; p less than 0.01). Either standard criterion for intracoronary thrombus or complex morphology was present in 70% of group I but only 21% of group II patients (chi 2 19.7; p less than 0.001). These results support a strong association of the angiographic descriptors of intraluminal thrombosis with the clinical syndrome of prolonged rest angina.(ABSTRACT TRUNCATED AT 250 WORDS)

Emergency percutaneous cardiopulmonary bypass support in cardiogenic shock from acute myocardial infarction

Emergency percutaneous cardiopulmonary bypass support was instituted in 8 consecutive patients, ages 42 to 80 years, in cardiogenic shock for 30 to 180 minutes (mean 106) due to acute myocardial infarction. The location of the infarction was inferior in 4, anterior in 3 and lateral in 1. Four patients had a history of prior myocardial infarction. Two patients were in cardiac arrest; the remaining 6 had a mean blood pressure of 43 to 55 mm Hg before the bypass. Five had pulmonary capillary Wedge pressure greater than or equal to 20 mm Hg. One patient, with a right ventricular infarction, had a pulmonary wedge pressure of 10 mm Hg. Percutaneous insertion of 20Fr cannulas was carried out. Flow rates of 3.2 to 5.2 liters/min were achieved. Two patients in cardiac arrest regained consciousness while still in ventricular fibrillation or asystole. Left ventricular ejection fraction ranged from 17 to 40% (mean 32). One patient had left main, 4 had multivessel, and 4 had 1-vessel coronary disease. Seven patients had successful angioplasty of 15 of 16 lesions attempted, with all infarct-related vessels successfully dilated. One patient had lesions unsuitable for either bypass or angioplasty and died. Need for blood transfusion was the most frequent complication. One patient required surgical repair of the femoral artery. All 7 patients are alive at a mean follow-up of 8.2 months. It is concluded that cardiopulmonary bypass can be safely instituted percutaneously, hemodynamically stabilize patients in cardiogenic shock and facilitate emergency complex coronary angioplasty, which may be life-saving.