[Evaluation of ischemic preconditioning on collateral circulation, ventricular function and clinical outcome in acute myocardial infarction]. / Valor do precondicionamento isquêmico na circulação colateral, função ventricular e evolução clínica no infarto agudo do miocárdio.

PURPOSE: To evaluate the influence of ischemic preconditioning (IP) in collateral circulation (CC), early ventricular function and in hospital outcomes after myocardial infarction (MI). METHODS: We studied 97 patients with a 1st anterior MI within 6h of pain and isolated total proximal occlusion of the left anterior descending artery, divided in 2 groups: with (GA) or without (GB) angina before MI. Coronariography and ventriculography were performed prior to reperfusion. The left ventricular (LV) ejection fraction was measured by the area length method and anterior wall motion by the centerline method. RESULTS: There was no difference between the two groups in sex, age, CKMB level, treatment, reperfusion rate. Global LV ejection fraction and anterior wall motion were similar, respectively, 39 +/- 9% and -2.55 +/- 1.17 SD/chord for GA and 37 +/- 8% and -2.75 +/- 0.79 and -2.75 +/- 0.79 SD/chord for GB (p = ns). The incidence of visible CC to the infarct area was also similar (present in 6 GA vs 8 GB patients). However, GA patients fared significantly better during hospitalization: No GA patient presented Killip class > or = 2 compared to 8 GB patients (p = 0.007). CONCLUSION: Although collateral coronary circulation grades, global and regional LV function were similar between the two groups, the presence of angina pectoris preceding an acute myocardial infarction was associated with a better in hospital evolution, what could be partially explained by preconditioning phoenomena.

Ridogrel does not increase the speed and rate of coronary recanalization in patients with myocardial infarction treated with alteplase and heparin.

Ridogrel, a compound with the dual property of inhibiting the synthesis of thromboxane and blocking the receptors of thromboxane/prostaglandin/endoperoxides, has been shown to accelerate the speed of recanalization and to delay or prevent reocclusion during systemic thrombolysis with tissue plasminogen activator in experimental animals. Ninety patients who had not taken any antiplatelet drugs within the last 10 days were randomized to either intravenous ASA 250 mg immediately before the thrombolytic treatment and 100 mg once a day orally thereafter or ridogrel 300 mg i.v. before thrombolytic treatment and 300 mg b.i.d. orally thereafter. All patients were given intravenous heparin concomitantly with alteplase. The patency of the infarct-related artery was determined by coronary angiography before the administration of the thrombolytic agent and by repeated coronary angiography every 15 min until the end of the administration of alteplase. A final angiogram was obtained 48 to 72 h later. At 90 min, the recanalization and patency rates were the same in the two treatment groups with no intergroup difference in the speed of recanalization.

Long-term function in the remote region after myocardial infarction: importance of significant coronary stenoses in the non-infarct-related artery.

BACKGROUND: Left ventricular (LV) function is the most important determinant of outcome after a myocardial infarction. Global LV function after a myocardial infarction is affected not only by wall motion in the infarct zone but also by regional function in the contralateral territory. It was hypothesised that the presence of significant stenoses in coronary arteries supplying the contralateral territory might influence the ability of this region to compensate for damaged myocardium after a myocardial infarction. METHODS AND RESULTS: 79 patients treated with thrombolysis for acute myocardial infarction had coronary and ventricular angiograms within 24 h and at a mean follow up of 12 months after myocardial infarction. Wall motion in the contralateral territory was analysed and scored by the centre line method and the change over time was correlated with the presence or absence of significant (> 70%) diameter stenoses in the non-infarct-related artery. Mean (SD) contralateral territory motion worsened, from 0.74 (1.78) to -1.55 (2.06) SD chord (p < 0.001) in 40 patients with stenoses, whereas contralateral territory motion improved from -0.02 (2.4) to 0.63 (2.21) SD chord (p < 0.05) in the 39 patients without coronary stenoses. The same pattern was present whether or not the infarct artery was patent. The global left ventricular ejection fraction at 12 months was also related to contralateral territory motion (r = 0.71, p < 0.001) and to the presence of coronary stenoses (54 (15)% in those with coronary stenoses and 62 (16)% in those without, p < 0.05). CONCLUSION: The results demonstrate that significant stenoses in arteries supplying the non-infarct territory adversely affect global and regional left ventricular function after a transmural infarction. Non-infarct artery anatomy should be considered in intervention strategies to improve left ventricular function after acute myocardial infarction.

[Fatal myocardial infarction in a young patient due to coronary arteritis]. / Infarto do miocárdio fatal em jovem causado por arterite coronária.

A 34 year-old male patient suffered an acute anterior wall infarction at age 32. Myocardial ischemia was demonstrated later by stress testing and thallium myocardial scintigraphy. Coronary arteriography revealed a proximal 90% obstruction of the left anterior descending artery. The patient was submitted to percutaneous transluminal coronary angioplasty. The procedure was unsuccessful as the catheter could not progress through the obstruction. On follow-up, there was less than ideal adherence to medical treatment and the patient complained of occasional atypical non-effort related chest pain. Two years later the patient suffered a large fatal myocardial infarction. Necropsy disclosed that the cause of myocardial infarction was severe coronary arteritis of left circumflex artery with giant cell granulomas.

Beta-blocker infusion did not improve left ventricular diastolic function in myocardial infarction: a Doppler echocardiography and cardiac catheterization study.

Left ventricular (LV) diastolic function changes after myocardial infarction. It has been suggested that beta blockers may improve diastolic function in hypertensive and heart failure patients. Doppler echocardiographic filling patterns and invasive hemodynamic indices have been used to analyze LV diastolic function. To determine the effect of beta blockers on LV diastolic function, we studied 32 patients with anterior wall myocardial infarction with a mean age of 53 years. Peak early and late flow velocities, peak early-to-late flow velocities ratio, pressure half time, diastolic filling period, isovolumic relaxation time, cardiac index, mean arterial pressure, wedge pressure, and systemic and pulmonary vascular resistance indices were obtained simultaneously before and after an intravenous infusion of 10 mg of atenolol. Cardiac index decreased from 4.27 +/- 0.97 to 3.19 +/- 0.91 l/min/m2 (p = 0.0001); mean arterial pressure decreased from 85 +/- 10 to 80 +/- 11 mmHg (p = 0.004); wedge pressure increased from 11 +/- 5 to 13 +/- 4 mmHg (p = 0.002); systemic vascular resistance index increased from 1586 +/- 409 to 1980 +/- 634 dyn.m2.s/cm5 (p = 0.0002); pulmonary vascular resistance index increased from 115 +/- 58 to 163 +/- 72 dyn.m2.s/cm5 (p = 0.0004); peak late flow velocity decreased from 64 +/- 15 to 49 +/- 14 cm/s (p = 0.0001); early-to-late ratio increased from 0.95 +/- 0.35 to 1.29 +/- 0.36 (p = 0.0001); diastolic filling period increased from 300 +/- 108 to 400 +/- 110 ms (p = 0.0001) and isovolumic relaxation time increased from 133 +/- 29 to 143 +/- 29 ms (p = 0.009). No significant changes were observed for peak early flow velocity and pressure half-time.(ABSTRACT TRUNCATED AT 250 WORDS)

Neurological complications after thrombolytic treatment for acute myocardial infarction: emphasis on unprecedented manifestations.

We examined 348 patients who underwent thrombolytic treatment for acute myocardial infarction. Nine patients (2.58%) developed neurological complications related directly or indirectly to this procedure. Cerebral hemorrhage occurred in 3 patients; 2 patients had transient ischemic attacks, 1 had syncope, another had psychomotor agitation and 2 patients presented seizures during the infusion of the thrombolytic agent, without hemodynamic abnormalities. This latter feature had never been described before.

Coronary recanalization rate after intravenous bolus of alteplase in acute myocardial infarction.

The demonstration in animals that recombinant tissue-type plasminogen activator produces prolonged thrombolysis after its clearance from the circulation has prompted a few pilot studies of bolus administration in patients. Alteplase (bolus dose of 70 mg) resulted in the highest recanalization rate in our previous pilot study comparing bolus doses of 50, 60 and 70 mg of alteplase in patients with acute myocardial infarction. The aim of the present trial was to assess the efficacy and safety of the same bolus dose in a larger number of patients. A further objective was to study the angiographic reocclusion rate at 12 to 24 hours in patients who had a recanalized infarct-related coronary artery at 90 minutes and were randomized at that time to a bolus dose or an infusion for 3 hours of 30 mg of alteplase. Sixty patients with acute myocardial infarction and angiographically documented total occlusion of the infarct-related coronary artery before thrombolysis were treated within 5 hours of onset of symptoms with an intravenous 70-mg bolus dose of alteplase (or 80 mg if body weight was greater than or equal to 90 kg). Each patient received 5,000 IU of heparin intraarterially and 100 mg of aspirin by mouth before administration of alteplase. Coronary angiography was repeated 60 and 90 minutes after alteplase administration. The recanalization rate of the infarct-related coronary artery was 55% (95% confidence interval, 43 to 66%) at 60 minutes and 48% (95% confidence interval, 37 to 60%) at 90 minutes. Pretreatment levels of lipoprotein (a) were not significantly related to recanalization.(ABSTRACT TRUNCATED AT 250 WORDS)

Usefulness of high-frequency analysis of signal-averaged surface electrocardiograms in acute myocardial infarction before and after coronary thrombolysis for assessing coronary reperfusion.

The incidence of late potentials on the signal-averaged electrocardiogram before and after coronary thrombolysis was studied in 54 patients with an acute myocardial infarction of less than or equal to 5 hours' duration and with an angiographically documented total occlusion of the infarct-related coronary artery on admission. A significant (p = 0.038) 50% relative reduction in the incidence of late potentials was observed in the group of 35 patients who underwent reperfusion: from 16 of 35 (46%) before to 8 of 35 (23%) at 120 minutes after the start of thrombolytic treatment. No significant reduction was seen in the 19 patients in whom thrombolysis was unsuccessful: from 8 of 19 (42%) before to 7 of 19 (37%) afterward. Despite successful recanalization, late potentials persisted or newly developed after thrombolytic therapy in 8 of 54 patients (15%). It is concluded that successful thrombolysis reduces the incidence of late potentials on the signal-averaged electrocardiogram but that the sensitivity and specificity of this finding are not high enough to allow reliable monitoring of coronary reperfusion at the bedside.

[Late potentials in patients with myocardial infarction subjected to coronary thrombolysis]. / Comportamento dos potenciais tardios em portadores de infarto do miocárdio submetidos à trombólise coronária.

PURPOSE: Analyse the behavior of the late potentials (LP) in patients submitted to thrombolysis with success. MATERIAL AND METHODS: Thirty-five patients with acute myocardial infarction, 32 (91.4%) male with ages varying from 33 to 68 (mean 52.6). Thrombolysis was obtained during cinecoronarography with intravenous infusion "in bolus" of doses of 50 mg, 60 mg and 70 mg of rt-PA, with a new bolus of 30 mg at 60 minutes after the procedure. A new angiographic study was performed 12-48 hours late. The high resolution ECG was taken with the ART system model 1200 EPX, before, after and 72 hours later. The presence of electrical activity in the last 40 ms of the QRS complex with less than 20 mu volts in amplitude and more than 35 ms in duration characterized the LP. RESULTS: LP was observed in 16 (46%) patients during the phase of arterial occlusion. LP was recorded only in 23% after recanalization and in 26% when the infarcted related artery (IRA) remain opened. The reduction in the LP was 43.5%. Only one patient with LP had threatening arrhythmia. CONCLUSION: In patients with demonstrated thrombotic occlusion of the IRA, the recanalization diminished the incidence of LP in 43.5% of the patients. Further studies are necessary to achieve the exact clinical importance of these findings.

Reperfusion arrhythmias in acute myocardial infarction--fact or coincidence?

Reperfusion arrhythmias were studied in a group of 20 patients submitted to coronary thrombolysis in the early hours of acute myocardial infarction. Arrhythmias were observed in 15 (75%) patients and consisted of ventricular arrhythmias and/or sinus bradycardia; 11/13 patients with reperfusion ventricular arrhythmias had the same type of arrhythmias before the procedure. This study group was compared to another group of 22 patients with acute myocardial infarction treated conventionally. There was no difference between both groups in regard to the incidence and type of ventricular arrhythmias. Sinus bradycardia only occurred during reperfusion in the study group and was significantly predominant in this group when compared with control group.