Primary Angioplasty in Acute Myocardial Infarction | James Tcheng | Springer
Table II shows the bivariate associations of the different factors with this worse in-hospital evolution. The variables independently associated with in-hospital mortality were analyzed with a model of multiple logistic regression tab. The mean duration of hospitalization was 8. Cardiac complications occurred in 21 In regard to the need for new revascularization procedures, new myocardial revascularization was required in 7 6.
Of the patients who survived, In 98 patients, echocardiography with acoustic quantification was performed to assess the ventricular function on the day of hospital discharge, and the mean ejection fraction of the patients was Ten Progression of the disease in a site other than that dilated was observed in 3 Before the date scheduled for reassessment, major clinical events occurred, and they are listed in table IV. Of the patients who were discharged asymptomatic, 26 had 1 event, and 4 were lost or were withdrawn from the study; therefore, the clinical reassessment proposed was carried out in 70 patients, who represented Figure 1 shows the Kaplan-Meier curve depicting total survival until the date of the new medical visit, and survival free from an event until the end of the study.
The mean follow-up was At the time of clinical follow-up, 57 Echocardiography with acoustic quantification was performed in all 70 patients who returned for follow-up with no clinical events. The mean ejection fraction was It is noteworthy that, in these cases, no statistically significant difference was observed between the echocardiographic measurement at the time of hospital discharge The factors associated with worse clinical evolution major events through the bivariate analysis are shown in table V. A reduction in the rate of events was only observed in the patients with stent implantation and coronary disease restricted to 1 vessel.
These variables, which associated with a higher incidence of events in an independent manner, were analyzed with a multiple logistic regression model tab. Figure 2 shows, with the aid of a Kaplan-Meier curve, the best evolution during the period of observation of those patients who had received stents during primary angioplasty in regard to major events. Discussion Primary angioplasty is not the most common treatment for myocardial reperfusion at our institution.
Primary angioplasty was the choice in the most severely ill patients, in those at higher risk, in those with contraindications to other procedures, and in those cases in which the soliciting physician was certain about that being the best method. In regard to the predominance of the male sex, mean age, time delay for initiation of treatment, vessel treated, location of the infarct, and initial flow assessed according to the TIMI classification 34 , data are similar to those found in other series reported in the literature On the other hand, in regard to the previous pathological history, hypertension, tobacco use, diabetes mellitus, dyslipidemia, previous infarction, and obesity, these data are largely variable when compared with those of other series 28,35, This may be due to the fact that this was a heterogeneous nonrandomized population, and, therefore, not reliably representing all those patients with acute myocardial infarction.
The high number of patients with Killip III and IV functional classes and with mean blood pressure below 60mmHg in our study is noteworthy. The reason for performing primary angioplasty for the treatment of acute myocardial infarction is difficult to compare, because most studies are randomized, and, consequently, only those 2 alternatives exist. Smyth et al 38 , in their cohort study in New Zealand, report data very similar to that here presented.
Therefore, it seems that, in nonrandomized studies, the reasons are similarly distributed, considering local rules and routines. The in-hospital mortality of The clinical trials are far less strict in defining success, considering only the patients undergoing the procedure and not the total sum of the randomized patients. In addition, in these clinical trials, the patients, in whom TIMI 2 flow is obtained, are included in the success group, and, frequently, those patients in poorer clinical condition are not considered. To avoid the effect of colinearity, blood pressure was excluded from the model of multiple logistic regression, and, due to conceptual reasons, because survival was a criterion of success of the procedure, angiographic success was also excluded to avoid a confounding bias.
These findings are supported by those of the PAMI study 23 , MITI study 29 , and the studies by Garcia et al 39 and Azmus 41 , which proved that advanced age was a variable independently associated with higher mortality. Functional class, as defined by the criteria of Killip-Kimbal at hospital admission, was the major determinant of worse in-hospital evolution.
Mortality in this subgroup was The occurrence of Better results are known to be directly related to the duration and quality of the procedure. Well-known data from clinical trials with thrombolytic agents 1 show a linear reduction in mortality as soon as the treatment is started. The same may be properly applied to primary angioplasty The mean time duration in this series was 3. Quality of reperfusion is a synonym for flow restoration, expressed by TIMI 34 ; it is currently a consensus that obtainment of TIMI 3 flow is associated with a better prognosis and greater preservation of the cardiac muscle than that of TIMI 2 flow These results are more evident in subgroups of diabetic patients with infarction of the anterior wall.
Therefore, we emphasize the objective of this series to value as successful only the obtainment of plain anterograde coronary flow TIMI 3 flow. Even though mortality does not change, the occurrence of complications in the in-hospital phase, specifically angina or reinfarction, is known to be lower in patients undergoing primary angioplasty as compared with those undergoing thrombolysis In our study, these complications added to Therefore, excluding the deaths, which characterized a more severely ill population, our population is in accordance with the selected patients of other studies.
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The relation between coronary patency and preservation of ventricular function is well defined. Because we believe that a long-term beneficial effect with recovery of the hibernating and stunned myocardium and a reduction in the ventricular remodeling exist, we chose a later comparative analysis. The mean value of ventricular function of On the other hand, the late results of the PAMI study have shown a mortality rate of 1.
Garcia et al 39 reported a mortality rate of 1. When the results of these latter series are compared with ours, one may see that the mortality rate in our series by the end of 12 months is low. Therefore, those patients who were discharged asymptomatic comprised a group very distinct from those with poor in-hospital evolution, because they had a high rate of survival, which may be explained by the fact that most of this group had normal ventricular function and good clinical management. In the study by Garcia et al 39 , this rate was 3. In the PAMI study, the recurrence rate of nonfatal acute myocardial infarction in 6 months was 2.
Zijlstra et al 52 reported lower figures with 2. Therefore, our population seems to behave in accordance with that in other studies in this regard. The need for a new percutaneous or surgical revascularization procedure is another interesting point. Once again, the good outcome of this cohort study as compared with others is noteworthy. In our study, we classified stroke, anginal pain, and heart failure requiring hospital admission as major cardiovascular events, unlike the large studies, which do not characterize these events like we did.
Preliminary studies have already pointed out this trend 53 , especially in optimizing the results of less satisfactory conventional angioplasties. Short clinical trials have shown the potential superiority of stent implantation upon conventional angioplasty with a combined reduction in mortality, restenosis, and need for new revascularization in the group treated with stent as compared with that treated with balloon. Larger studies have confirmed this trend. It has already been shown that these advantages do not translate into a reduction in mortality but in nonfatal events.
The most important finding in this study is that it defines a group of patients who should receive more aggressive treatment. Primary balloon angioplasty was safe and more effective than thrombolysis. Balloon Angioplasty or Coronary Stenting? The limitations of primary balloon angioplasty led some researchers to include stents in the therapeutic arsenal for treating AMI.
At first infarction was considered a contraindication for stenting due to the theoretical risk of occlusion when implanting it in lesions with high thrombotic content. Numerous published studies and registries have demonstrated the safety and efficacy of stenting during primary PTCA.. The patients had a low incidence of hospital death 0. In a later publication, the results of 7-month follow-up 25 were presented with data from patients. Mortality was 1. Angiographic restenosis was The number of stents and the vessel reference diameter were determinants of TVR.
Grines et al 26 published a study which compared PTCA with and without stenting. A total of patients were included. The combined primary end point of death, reinfarction, disabling stoke, and TVR was also significantly smaller. However, in the group treated with stenting a trend was observed toward greater mortality at 12 months, although it did not reach significance. This coincided with a smaller degree of TIMI grade 3 flow in the stent group, probably due to distal embolization of the thrombus previously fragmented by predilatation with the balloon.
The PASTA study 28 demonstrated that primary PTCA with stenting in selected patients had a low incidence of major cardiac events during the first 12 months and lower rates of restenosis compared to balloon angioplasty.. The primary end point was the combination of death, reinfarction, disabling stroke or ischemia-driven TVR at 6 months. There were no significant differences in the primary end points between the 2 primary angioplasty groups, neither were there differences between the 2 stenting groups. On the other hand, significant differences were observed in the combined primary end point at 6 months between primary PTCA and the stent group due to a lower rate of target vessel revascularization with stenting, with no differences in mortality or stroke.
The apparent absence of relative benefit of abciximab with stenting at 6 months is due to the great relative weight of stenting in reducing restenosis, the most powerful component of the combined end point. The benefit of abciximab 33 was demonstrated in the analysis of the results at 30 days..
It is currently accepted that stenting is used as a reference in percutaneous revascularization of the AMI culprit vessel. It has been thought that one way to decrease distal embolization could be direct stenting Figures 1 and 2 without predilatation with balloon. Loubeyre et al 35 presented a work which compared direct stenting with predilatation in AMI patients.. Other authors have also confirmed good outcomes with direct stenting. It is currently believed that primary PTCA with direct stenting is advisable in lesions with a great amount of thrombotic material visualized via angiography, in young patients with suspicion of soft lesions, and in cases where thrombus aspiration devices were not used.
When there are calcified lesions or when inadequate stent expansion is suspected, predilatation is recommended.. Figure 1. A The right coronary artery with subocclusive stenosis in the middle third. B Final result after direct stenting.. The outcome is worse in AMI patients with diabetes than in non-diabetic patients. However, there were significant differences in the group treated with stenting compared to patients treated with balloon angioplasty. Harjai et al 39 showed that diabetic patients had a greater proportion of multiple-vessel disease, but had better TIMI grade 3 flow at admission.
Hospital mortality was 4. High mortality in diabetic patients is due to the fact they have larger infarctions, with greater LVEF dysfunction and greater incidence of kidney failure.. There is much debate regarding the scope of percutaneous revascularization in patients with multiple vessel lesions in the AMI context.
Pellizzon et al 40 compared 2 groups of patients: those with revascularization in the AMI culprit artery only or together with other vessels. There were no differences in reinfarction and revascularization rates after 1 year. However, with current improvements in materials, in patients in whom adequate collateral flow should be ensured or who have lesions in other vessels but where an increase in procedural difficulty is not expected, some authors revascularize other vessels during the same procedure and this decreases morbidity, hospital stay, and costs..
In comparison with native artery revascularization, the grafts had TIMI grade 3 flow with more thrombus. The patients with previous surgery had greater hospital mortality than nonoperated patients, especially if the treated vessel was a graft. Are Drug-Eluting Stents Indicated?
With the advent of drug-eluting stents DES the incidence of restenosis has been reduced. Lemos et al 49 presented a study on the short- and long-term benefits of DES in patients, comparing them with conventional stents.. There were no differences between groups in vessel patency, infarct size enzyme markers , and short-term events, nor were there were differences in stent thrombosis. These results should still be confirmed by randomized studies.. Epicardial Flow and Myocardial Reperfusion. Traditionally, the good outcome of primary angioplasty has been associated with obtaining normal epicardial flow early and sustained TIMI grade 3 in the AMI culprit artery.
Studies were published evaluating myocardial perfusion 52 via contrast echocardiography, 53 positron emission tomography, 54 and magnetic resonance imaging 55 where it was demonstrated that, despite obtaining TIMI grade 3 flow, adequate tissue reperfusion was not always achieved.
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Van't Hof et al 57 introduced the term myocardial blush MB grade, an angiographic method to describe the effectiveness of myocardial perfusion that was validated in relation to the extent of ST-segment elevation resolution in the electrocardiogram ECG. Myocardial blush grade was associated with increased mortality as the degree of perfusion decreased.. Stone et al 58 evaluated the importance of myocardial perfusion.
However, of these, MB was normal in Another component of great value when evaluating reperfusion is ST-segment elevation resolution in the ECG after catheterization. The persistence of ST-segment elevation after recanalization reflects the presence of sustained transmural lesion and is correlated with alterations in reperfusion and microcirculation dysfunction involving great myocardial damage. Claeys et al 59 studied the prognostic value of postcatheterization ST-segment resolution in 91 AMI patients.
The development of reperfusion injury is related to an increase in microvascular injury and arrhythmias and even sudden death and perpetuation of the thrombotic state. The microvasculature would be highly exposed to procoagulant factors, inhibition of the fibrinolytic system, and platelet aggregation, partly due to the reduction in nitric oxide, all of which would induce microvascular occlusion. Matetzky et al 64 evaluated the persistence of ST-segment elevation in patients.
The patients with no-reflow have a greater risk of infarction and death. The causative mechanisms are: arterial vasoconstriction, loss of capillary self-regulation, distal embolization, microvascular disorder, tissue edema, increased inflammatory mediators, endothelial alteration or increases in vasoconstrictor receptors such as angiotensin-II. Thrombectomy and Distal Protection Devices. A common angiographic finding is thrombus associated with a lesion leading to difficulties in obtaining adequate myocardial perfusion.
Most myocardial infarctions begin with the formation of thrombus on broken plaque and later occlusion of the artery. Despite significant progress in the development of antiplatelet aggregation and antithrombotic agents, the persistence of thrombus debris in lesions is strongly associated with a high risk of distal embolization and no-reflow events leading to poor angiographic and clinical outcomes. The mechanical approaches developed include thrombus aspiration catheters, rheolytic systems, ultrasound lysis, distal protection devices, and mechanical thrombectomy.
Moreno et al 67 report their initial experience of 4 patients with AMI who underwent removal of intracoronary thrombus. In the most extensive experiment involving several Spanish and Italian centers, the same level of safety and efficacy were obtained in a broad group of patients with AMI.. Brueck et al 68 reported a patient with aortocoronary bypass graft stenosis who underwent successful rescue thrombectomy without complications after the implantation of 2 stents for occlusion of the native artery; this fact suggests that the X-Sizer system is able to recover the thrombotic debris after macroembolization of the saphenous vein graft, including the native coronary artery.
Kwok et al 69 evaluated the first angiographic results in humans, involving 14 patients who underwent intracoronary thrombectomy with the X-Sizer system.. The mean stenosis diameter was reduced by No differences were found regarding the primary end point periprocedural infarction , but the patients in whom the X-Sizer system was used had a lower incidence of large periprocedural infarctions, especially when the target lesion was in native arteries..
Figure 2. A Complete occlusion of the anterior descending coronary artery in the middle third. The passage of the X-Sizer through the occlusion can be seen in the box. B Result after thrombectomy. The final outcome can be seen in the box after implanting the stent.
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C and D X-Sizer system catheter and device.. Beran et al 71 prospectively compared conventional PCI with pretreatment with the X-Sizer system in 65 patients with similar clinical characteristics, of whom 49 had AMI. Napodano et al 72 evaluated the effects of mechanical thrombectomy with the X-Sizer system on myocardial reperfusion during primary angioplasty in 92 patients with angiographic evidence of intraluminal thrombus, who were randomized for intracoronary thrombectomy followed by stenting or a conventional stenting strategy.
Myocardial reperfusion was evaluated by myocardial blush and ST resolution. Thrombolysis In Myocardial Infarction grade 3 flow was similar in both groups.
Primary Angioplasty in Acute Myocardial Infarction
Myocardial blush grade 3 was found in The primary end point was the magnitude of postprocedural ST-segment resolution which was significantly better in the group treated with the X-Sizer system. Figure 3. Console and catheters for rheolytic thrombectomy AngioJet.. Nakagawa et al 75 studied the efficacy and safety of the AngioJet catheter in 31 patients with AMI with angiographic follow-up at 3 and 6 months. There were no major in-hospital events and none during follow-up.. The results of a randomized multicenter study done in the USA were recently published which compared rheolytic thrombectomy using the AngioJet system with conventional coronary intervention in patients with ST-segment elevation AMI.
The AngioJet system was unable to decrease the infarct size compared to conventional intervention or improve ST-segment resolution. The use of rheolytic thrombectomy using the AngioJet system increased the incidence of complications, including mortality compared to conventional interventional therapy.
In summary, the AngioJet system was less safe and effective than conventional intervention. In several multicenter trials, the use of the PercuSurge GuideWire device has been effective in reducing the incidence of distal embolization in the treatment of degenerated saphenous vein grafts 77,78 Figure Wu et al 80 evaluated angiographic results at 6 months and perfusion at the site of the distal protection balloon in patients with AMI. Seventy-four patients were treated with the PercuSurge device.
In this randomized multicenter study, the PercuSurge device was no more effective than conventional intervention for ST-segment resolution and microvascular flow; neither was it safer nor able to reduce mortality and total events.. Some small observational studies have shown its efficacy in saphenous vein graft angioplasty. Procedural success was similar regarding epicardial flow, angiographic complications, and immediate major events or those at 30 days.. Limbruno et al 85 evaluated the safety and efficacy of FW as an adjunct to primary angioplasty in 53 patients with AMI compared to a control group treated with conventional primary angioplasty..
A large randomized study is needed to compare the results of primary angioplasty with and without distal protection with FW to determine the real part played by this device.. Figure 6. FilterWire Ex Distal protection filter.. Hypothetical reductions in infarct size achieved via circulatory hypothermia have been verified by Dixon et al 86 in the COOL-MI study which compared patients undergoing conventional primary angioplasty with others who underwent systemic hypothermia in addition to primary angioplasty.
Adverse events were similar in the 2 groups. No differences were found regarding the study's primary end point infarct size , although in the anterior infarction subgroup, the infarct size was smaller in those patients where it was possible to achieve a deep level of hypothermia. One problem is that patients find this difficult to tolerate.. The future role of this technique is still to be determined, but it will be necessary to find a way to make it more comfortable and to find patient subgroups in which hypothermia can lead to significant clinical differences: large infarctions, late presentation, previous ventricular dysfunction, etc..
Different theories have been proposed to explain this and, in turn, it has been thought that different therapeutic strategies could be used in its prevention. Among the therapies proposed are the administration of fluosol, magnesium, trimetazidine, cylexin, adenosine, anti-CD18, eniporide, etc.. Pexelizumab is one of the latest drugs proposed as being efficacious in preventing damage due to reperfusion which, via inhibiting complement C5, should reduce myocardial damage. Granger et al 88 tested the safety and efficacy of pexelizumab in the COMMA study, where its effect was tested in randomized patients.
Although there were no significant differences in the primary end point, the infarct size, there was a difference in 6-month mortality in the patients treated with pexelizumab. In many countries, due to decentralization and streamlining the health systems, there is a lack of centers with experience in primary PTCA and even hospitals without a catheterization laboratory or on-site cardiac surgery which could solve complications arising from percutaneous revascularization. For this reason, some authors and guidelines advocate the use of thrombolytic therapy in the patients who arrive at these centers, with referral to percutaneous revascularization or surgery as required.
Based on this, some authors have suggested the creation of centers with experience in catheterization lacking on-site cardiac surgery or transfer to centers with greater expertise.. In the first case, the results were significantly better. The NRMI 90 study compared revascularization in centers with and without on-site cardiac surgery.
The door-balloon time was min. There were no deaths during transferal. More beta-blockers, abciximab, and stents were used in the nontransferred group. There were no significant differences in length of hospital stay. Nor were there significant differences in the primary end point at 30 days. There was no differences per year in the rates of reinfarction, disabling stroke or combined end points.
Primary PTCA can be carried out safely in centers without on-site cardiac surgery with similar results.
Early Stent Thrombosis after Percutaneous Coronary Intervention for Acute Myocardial Infarction
Vessel patency and long-term evolution are not necessarily related to the time of PTCA. The study finished prematurely with patients. There were no deaths or need for resuscitation during transfer. The length of hospital stay was significantly shorter in the patients treated with PTCA. At 30 days there were no significant differences in the primary end point. Three hundred patients were included in the study.
There were no complications in the third group during transfer. The results were similar in the first 2 groups. In the PRAGUE 2 study, Widimsky et al 97 evaluated patients with AMI and compared their transfer to a center with a catheterization laboratory to on-site thrombolysis in the admission hospital. Thirty-day mortality was 6. It was stopped prematurely due to the demonstrated benefits of PTCA. Mean time from symptom onset to randomization was min. The difference was significant regardless of the location of the infarction, whether inferior or anterior. These studies demonstrate that the transfer of patients with AMI to centers that have catheterization laboratories yields better results, fewer adverse events, and better long-term prognosis than on-site thrombolysis..
Zijsltra et al 11 carried out a metaanalysis of the randomized studies that compared transfer to another center for PTCA versus on-site thrombolysis. Mortality was 6. Keeley et al 12 carried out a similar metaanalysis. Despite the delay in transfer, primary PTCA significantly reduced non-fatal reinfarction, stroke, and other adverse events..
The term facilitated angioplasty refers to the use of pharmacological agents to achieve reperfusion before arrival at the catheterization laboratory. The aim is to achieve a greater number of patients with the AMI culprit artery open upon arrival at the admitting hospital and to preserve ventricular function while avoiding an increase in complications.
Stone et al 99 analyzed the importance of TIMI grade 3 flow upon arrival at the catheterization laboratory based on patients included in the PAMI studies. These patients were compared to those with smaller TIMI flow. These results point to the advisability of facilitated PTCA.. The HEAP study did not find the use of high-dose heparin of benefit as pretreatment for angioplasty. However, there were no differences in obtaining TIMI grade 3 flow at the end of the trial. During follow-up there was a trend toward better LVEF in the second group.
There were no significant differences between groups in the combined end point 8. The GRACIA 1 study compared 2 postinfarction strategies following thrombolysis: a invasive: systematic coronary angiography and revascularization if indicated ; and b coronary angiography following an ischemia-guided conservative approach.. Technical, professional, and administrative aspects are reviewed in clear detail. Among the topics covered are the technique and technology of direct angioplasty, patient selection, regulatory issues, performance metrics, clinical trials and outcomes, adjunctive pharmacology, economics, and implications for the health care system.
The practicing cardiologist will appreciate the many useful how-to tips and pointers; the cardiology fellow will value the a-to-z approach that addresses all critical issues; and the administrator will learn the details of creating, maintaining, evaluating, and justifying a successful program. Comprehensive and highly practical Primary Angioplasty in Acute Myocardial Infarction, Second Edition summarizes for today's cardiologists, internists, family practitioners, and emergency room physicians all the accumulated knowledge and experience needed to ensure that primary angioplasty becomes the standard of care for acute myocardial infarctions.