Percutaneous Coronary Intervention 

Since the first human percutaneous transluminal coronary angioplasty (PTCA) procedure was performed in 1977, the use of percutaneous coronary intervention (PCI) has increased dramatically; it is now one of the most commonly medical performed interventions. Originally developed in Switzerland by Andreas Gruentzig, PCI has transformed the practice of revascularization for coronary artery disease (CAD).

Coronary angioplasty, initially used in the treatment of patients with stable angina and discrete lesions in a single coronary artery, currently has multiple indications, including unstable angina, acute myocardial infarction (AMI), and multivessel CAD. With the combination of sophisticated equipment, experienced operators, and modern drug therapy, PCI has evolved into an effective nonsurgical modality for treating patients with CAD. Ongoing technical advances are allowing more patients with chronic total occlusions (CTOs) to be successfully treated percutaneously.

Improvements in catheter technique and the development of new devices and medications have paralleled our growing understanding of cardiovascular physiology, the pathogenesis of atherosclerosis, and the response to vascular injury. Intracoronary stents and atherectomy devices have been developed to increase the success and decrease the complications of conventional balloon dilation, as well as to expand the indications for revascularization. Interventionalists now can safely treat more complex coronary lesions and restenosis.

The development of drug-eluting stents has substantially reduced the problems of restenosis seen with bare-metal stents. At the same time, advances in intravascular ultrasonography (IVUS) and fractional flow reserve (FFR) evaluation have improved the understanding of coronary plaque morphology, plaque vulnerability, and coronary physiology.

Furthermore, many of these technologies are able to help identify patients who will benefit most from PCI, coronary artery bypass grafting (CABG), or medical therapy. Adjunctive pharmacologic therapies aimed at preventing acute reocclusion have also improved the safety and efficacy of coronary angioplasty.

The growth of PCI has been remarkable. Stents are now used in more than 80% of PCI cases in the United States. This growth will probably be sustained for some time yet because these new technologies have been found to result in improved outcomes. Over the past 2 decades, innovations in PCI have been paralleled by dramatic reductions in 30-day death, myocardial infarction, and target-vessel revascularization rates. (See Unstable Angina.)

Clinical indications for PCI include the following:

• Acute ST-elevation myocardial infarction (STEMI)
• Non–ST-elevation acute coronary syndrome (NSTE-ACS)
• Stable angina
• Anginal equivalent (eg, dyspnea, arrhythmia, or dizziness or syncope)
• Asymptomatic or mildly symptomatic patient with objective evidence of a moderate-sized to large area of viable myocardium or moderate to severe ischemia on noninvasive testing

Angiographic indications include hemodynamically significant lesions in vessels serving viable myocardium (vessel diameter >1.5 mm).

Clinical contraindications for PCI include any significant comorbid conditions present (this is a relative contraindication). Angiographic contraindications include the following:

• Left main stenosis in a patient who is a surgical candidate (although CABG is still the preferred treatment for left main stenosis, this area is rapidly evolving toward safe and feasible PCI options^[1] )
• Diffusely diseased small-caliber artery or vein graft
• Other coronary anatomy not amenable to PCI

In a major 2009 task force report, the use of coronary revascularization for patients with acute coronary syndromes and combinations of significant symptoms or ischemia was generally viewed favorably.^[2] However, the use revascularization for asymptomatic patients or patients with low-risk findings on noninvasive testing and minimal medical therapy was viewed less favorably.

Rao et al examined the safety of same-day discharge in 107,018 low-risk patients 65 years or older who underwent elective PCI at 903 sites.^[3] Only 1.25% of patients were discharged on the same day, and there was significant variation across facilities. Patients who were discharged on the same day had shorter procedures with less multivessel intervention. Notably, there were no significant differences between same-day discharge and overnight stay patients with regard to mortality or rehospitalization rate either at 2 days or at 30 days.

PCI vs medical therapy: stable angina

Early trials demonstrated the advantages of PCI over medical therapy for symptomatic angina in single-vessel and multivessel CAD, with amelioration of symptoms, reduction of the need to take antianginal medications, improvement in exercise duration, and maintenance of survival rates comparable to those of medical therapy.^{[4, 5, 6]}

The Randomized Intervention in the Treatment of Angina (RITA-II) study, in which 1018 patients with stable angina were randomized to balloon angioplasty or medical therapy, demonstrated that balloon angioplasty results in better control of ischemic symptoms and greater improvement in exercise capacity than medical therapy does, though balloon angioplasty is associated with an increased incidence of the combined endpoint of death and myocardial infarction.^[7]

In this study, death or definite myocardial infarction occurred in 6.3% of the balloon angioplasty patients and in 3.3% of the medical patients; only 44% of the deaths were actually due to heart disease.^[7] Angina improved in both groups, but a 16.5% absolute excess of grade 2 or worse angina was noted in the medical group 3 months after randomization.

In the medical group, 23% of patients required revascularization during follow-up.^[7] In the angioplasty group, 7.9% of patients required bypass surgery during follow-up, compared with 5.8% in the medically treated group. It is important to emphasize that although the patients in RITA-II were asymptomatic or mildly symptomatic, most had severe anatomic CAD: 62% had multivessel CAD, and 34% had important disease of the proximal left anterior descending (LAD) artery.

The Atorvastatin Versus Revascularization Treatment (AVERT) trial found that 13% of the medically treated group and 21% of the angioplasty group had ischemic events at 18 months, suggesting that in low-risk patients with stable CAD, aggressive lipid-lowering therapy may reduce ischemic events as effectively as balloon angioplasty does.^[8] A total of 341 patients with stable CAD symptoms, normal left ventricle (LV) function, and class I or II angina were assigned randomly to balloon angioplasty or atorvastatin therapy.

On the basis of the limited data available from randomized trials comparing medical therapy with balloon angioplasty, it seems appropriate to consider medical therapy for initial management of most patients with Canadian Cardiovascular Society Classification class I and II symptoms, and to reserve percutaneous or surgical revascularization for patients with more severe symptoms and ischemia.

The Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation (COURAGE) trial demonstrated that in patients with stable angina symptoms and coronary artery stenosis, medical therapy alone may be an appropriate strategy if such therapy can control the angina symptoms. The trial randomized the addition of PCI to intensive pharmacologic therapy, with the endpoints of death from any cause and nonfatal myocardial infarction during a median follow-up period of 4.6 years.

Inclusion criteria for the COURAGE study included the presence of a 70% or greater lesion in 1 or more proximal epicardial arteries, American College of Cardiology (ACC)/American Heart Association (AHA) class I or II indications for PCI, and objective evidence of myocardial ischemia on stress testing. For both primary endpoints, there was no statistically significant difference between patients who received PCI with medical therapy and those who received only medical therapy.

Teo et al found that in older patients with stable CAD, optimal medical treatment without PCI remains an appropriate initial management strategy.^[9] Analysis of 904 patients aged 65 years or older showed that, during a median 4.6-year follow-up, clinical outcome was no better or worse in patients randomized to optimal medical treatment plus PCI than in patients who received optimal medical treatment alone.

Compared with 1381 patients younger than 65 years with CAD, older patients had similar success in achieving treatment targets and similar rates of myocardial infarction, stroke, and major cardiac events, although the death rate was 2- to 3-fold higher in the older patients.^[9] It should be kept that the analysis was done from patients enrolled in the COURAGE trial, and thus the following limitations of that study must be taken into account:

• All patients underwent angiography before enrollment
• Only 1 in 12 patients who were screened were actually enrolled
• At the time of enrollment, most patients were either asymptomatic or had minimal symptoms

Overall, medical therapy is recommended as first-line therapy in patients with stable angina unless 1 or more of the following indications for cardiac catheterization and PCI or CABG are present:

• A change in symptom severity
• Failed medical therapy
• High-risk coronary anatomy
• Worsening LV dysfunction

PCI vs surgical revascularization: stable angina

Two prospective clinical trials have evaluated balloon angioplasty against surgery for revascularization of isolated LAD artery disease.^{[10, 11]}

Using a combined endpoint (cardiac death, myocardial infarction, or refractory angina necessitating revascularization by surgery), the Medicine, Angioplasty, or Surgery Study (MASS) showed that after 3 years of follow-up, endpoint events occurred in 24% of angioplasty patients, 17% of medical patients, and 3% of surgical patients.^[10] However, overall survival rates were similar in the 3 groups.

The other trial evaluated balloon angioplasty against bypass surgery with an internal thoracic (mammary) artery graft to the LAD and also reported no difference in survival during follow-up.^[11] Although 94% of angioplasty patients and 95% of bypass patients were free of limiting symptoms, the former required more antianginal drugs. At 2.5 years’ follow-up, 86% of surgery patients were free from late events, compared with 43% of angioplasty patients. This difference was primarily due to restenosis requiring a second revascularization procedure.

It is important to emphasizing that balloon angioplasty, rather than stent placement, was used in both of these trials; with the growing use of stenting, current restenosis rates should be lower.

Five large (>300 patients) randomized trials comparing balloon angioplasty with bypass surgery in patients with multivessel CAD all showed that in appropriately selected patients, the rates of death or of myocardial infarction were similar regardless of which treatment was employed.^{[12, 13, 14, 15, 16]} However, more of the angioplasty-treated patients required a second revascularization procedure. The Table below summarizes 3 of these trials.

Table. Comparison of Surgical Therapy and Coronary Angioplasty (Open Table in a new window)

In the Bypass Angioplasty Revascularization Investigation (BARI), 5-year survival was 86.3% for those assigned to angioplasty versus 89.3% for those assigned to surgery, and 5-year freedom from Q-wave myocardial infarction was 78.7% for the former and 80.4% for the latter.^[15] However, after 5 years of follow-up, 54% of those assigned to angioplasty required an additional revascularization procedure, compared with only 8% of those assigned to surgery.

Similarly, the Argentine Randomized Trial of Percutaneous Transluminal Coronary Angioplasty Versus Coronary Artery Bypass Surgery in Multivessel Disease (ERACI) showed that freedom from combined cardiac events at 3 years was significantly better for bypass surgery than for angioplasty (77% vs 47%), though the groups did not differ in terms of overall and cardiac mortality or frequency of myocardial infarction.^[17] Bypass patients were more often free of angina (79% vs 57%) and had fewer additional revascularization procedures (6% vs 37%).

Patients with diabetes mellitus constitute an exception to the general findings that balloon angioplasty and bypass surgery yield essentially equivalent results in patients with multivessel disease.

Among diabetic patients in the BARI trial, 5-year survival was 65.5% in those treated by balloon angioplasty and 80.6% for those treated with bypass surgery.^[15] The improved survival with surgery was due to a reduced cardiac mortality (5.8% vs 20.6%) and was confined to those receiving at least 1 internal thoracic artery graft. Better survival among diabetic patients with multivessel disease treated with bypass surgery rather than angioplasty was also observed in a large retrospective study.

The Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D) trial randomized 2364 men and women with type 2 diabetes mellitus, documented CAD, stable symptoms, and myocardial ischemia treated with optimal medical therapy to an initial strategy of either coronary revascularization or watchful waiting with the option of subsequent revascularization. At 5 years, rates of survival or the composite endpoint of cardiovascular death, myocardial infarction, and stroke did not differ significantly between the groups.^[18]

A substudy of the BARI 2D trial reports that the coronary revascularization strategy improved outcomes at the 3-year follow-up, with patients experiencing a lower rate of worsening angina, new angina, and subsequent coronary revascularizations, as well as a higher rate of angina-free status.^[19]

In most patient subgroups with multivessel CAD, long-term mortality after CABG is comparable to that after PCI; therefore, the choice of treatment should depend on patient preferences for other outcomes. In a collaborative analysis of individual patient data from 10 randomized trials, Hlatky et al found CABG to be a superior option for patients with diabetes and patients aged 65 years or older because mortality was lower in these subgroups.^{[20, 21]}

Bare-metal stents vs CABG

The major limitations of balloon angioplasty have been acute vessel closure and restenosis. Early studies with intracoronary stents showed that these devices were highly effective for treating or preventing acute or threatened vessel closure and thereby avoiding emergency bypass surgery.

Two randomized trials, BENESTENT^[22] and STRESS,^[23] demonstrated that coronary stenting of de novo lesions in native vessels reduced angiographic restenosis by approximately 30% as compared with conventional balloon angioplasty. Stenting produces a larger lumen diameter than conventional balloon angioplasty both immediately after the procedure (acute gain) and at follow-up (net gain), resulting in less restenosis.

The use of stenting instead of balloon angioplasty was compared with bypass surgery for the treatment of multivessel CAD in the Arterial Revascularization Therapies Study (ARTS), and after 1 year of follow-up, no difference was noted between the groups in the rate of death, stroke, or myocardial infarction.^[24] Event-free survival was better in the surgery group than in the stent group (87.8% vs 73.8%), and only 3.5% in the surgery group required a second revascularization procedure, compared with 16.8% in the stent group.

In the ERACI^[17] and BARI^[15] trials, 37% and 54%, respectively, needed a second revascularization when treated by balloon angioplasty. Overall, patients with diabetes and those who received incomplete surgical revascularization did worse. The cost of the initial revascularization procedure was $4212 less for those treated with stent placement, but because of the need for more repeat revascularization procedures in the stent group, the cost advantage for stenting was reduced to $2973 after 1 year.

The Stent or Surgery (SoS) trial compared bare-metal stents with CABG in similar patients and reported a 2-year target vessel revascularization rate of 21% in stent patients, compared with 6% in CABG patients.^[25] Death and myocardial infarction rates were similar in the 2 groups. However, the SoS trial had a higher noncardiac death rate in the PCI arm, thought to be attributed to a type II error that may have affected the study results.

Few stent patients in the SoS trial received glycoprotein (GP) IIb/IIIa receptor inhibitors. Still, this and the ARTS study do point to the safety of PCI treatment in multivessel disease. Mortality risk is low (if noncardiac deaths are discounted), and the rates of repeat target vessel revascularization have been halved.^[26]

According to the New York Cardiac Registry, as with the prior trials, patients who received PCI as the initial therapy had a higher incidence of target vessel revascularization (35.1%) than those who received CABG (4.9%).^[27] The registry identified 59,314 patients with multivessel disease who either underwent CABG (37,212) or had PCI with bare-metal stents (22,102), with reported endpoints of repeat revascularization and survival rates within 3 years.

Using unadjusted survival curves, the registry demonstrated that for patients who had 2-vessel disease without LAD involvement, PCI offered a small survival benefit.^[27] For patients who had 2-vessel disease with proximal LAD involvement, the 2 procedures had similar mortalities (91.4% for CABG and 91.2% for PCI). The registry reported a statistically significant survival benefit of CABG over PCI in patients who had 3-vessel disease with proximal LAD involvement.

Drug-eluting stents vs CABG

In the ARTS II trial, a registry comparing the use of sirolimus-eluting stents with the PTCA and CABG arms of the ARTS I trial, the stents were associated with an 8% major cardiovascular events (MACE) rate (vs 13% for CABG in ARTS I) and an 8.5% target vessel revascularization rate (vs 4% for CABG and 21% for PTCA in ARTS I). The 1-year MACE rate was 10.5% for sirolimus-eluting stent patients.^[28]

The New York Cardiac Registry also found that patients who underwent PCI with a drug-eluting stent had a higher rate of target vessel revascularization than those who underwent CABG (30.6% vs 5.2%).^[27] They analyzed 17,400 patients who either received a drug-eluting stent (n = 9963) or underwent CABG (n = 7437) and observed them for 18 months. Unadjusted survival curves did not demonstrate a statistical significance in survival for 2- or 3-vessel disease.

Nevertheless, when adjustments were made for several factors (ie, age; sex; ejection fraction; hemodynamic state; history or no history of myocardial infarction before the procedure; the presence or absence of cerebrovascular disease, peripheral arterial disease, congestive heart failure, chronic obstructive pulmonary disease, diabetes, and renal failure; and involvement of the proximal LAD), CABG had a statistically significant 18-month survival benefit over PCI with drug-eluting stents.^[27]

The SYNTAX study, in which 1800 patients with 3-vessel or left main coronary artery disease were randomized to undergo CABG or PCI with paclitaxel-eluting stents, found that quality of life and angina scores were improved in both groups at 6 and 12 months.^[29] The angina score improved more in the CABG group, but the intergroup differences were small.

The ongoing FREEDOM trial will compare drug-eluting stents and CABG in patients with diabetes and multivessel coronary artery disease.

PCI in unstable angina and non–Q-wave myocardial infarction

The management of patients with non–Q-wave myocardial infarction and unstable angina has changed considerably over the past 5 years. Before the widespread use of stents and GPIIb/IIIa receptor inhibitors, conventional balloon angioplasty in this subgroup of patients was associated with substantial risks, including myocardial infarction (as much as 9%), restenosis (as much as 50%), need for emergency coronary bypass surgery (as much as 12%), and death (as much as 5%).

The optimal strategy in patients presenting with acute coronary syndromes remains a controversial issue in contemporary cardiology. Several studies have assessed the use of a conservative strategy against the use of an early invasive strategy of revascularization for patients with unstable coronary syndromes.

In the PROSPECT study, 697 patients with an acute coronary syndrome treated with PCI were evaluated at the time of the procedure with multivessel intravascular ultrasonography (grayscale and radiofrequency); adverse events during a median follow-up of 3.4 years were found to be divided evenly between recurrence at the site of culprit lesions and nonculprit lesions.^[30] IVUS predictors of nonculprit lesions that will progress include a large plaque burden, small luminal area, and thin-cap fibroatheroma.

The Veterans Affairs Non–Q-Wave Infarction Strategies in Hospital (VANQWISH) trial compared an invasive strategy with conservative medical treatment in patients with non–Q-wave myocardial infarction and found that the rates of death or nonfatal myocardial infarction were higher in the invasive strategy group than in the conservative strategy group before hospital discharge, at 1 month, and at 1 year.^[31]

Criticisms of this study include the exclusion of patients at very high risk; the lack of current aggressive medical therapies; a high rate of crossover to angiography in the conservative arm; a higher surgical mortality than expected in view of with contemporary standards; and the observation that most of the complications at 30 days occurred in patients who underwent CABG, with very few occurring in those who underwent balloon angioplasty.^[31]

In contrast to the VANQWISH trial, 3 randomized studies^{[32, 33, 34]} found that an early invasive approach in patients with acute coronary syndromes was associated with improved outcomes.

The Thrombolysis in Myocardial Infarction (TIMI) IIIb study showed less ischemia, shorter hospital stays, fewer readmissions, and fewer symptoms in patients treated by an early invasive approach.^[32]

The Fragmin and Fast Revascularization during Instability in Coronary Artery Disease (FRISC) II trial prospectively randomized 2457 patients to early invasive treatment with intracoronary stenting or noninvasive treatment and found that at 6 months, the composite endpoint of death or myocardial infarction was higher in the latter than in the former.^[33] Additionally, symptoms of angina and hospital readmissions were twice as common in the noninvasive arm as in the invasive arm.

The RITA-III study reported improved outcomes with early invasive therapy in 1810 patients at 5 years’ follow-up.^[34] There was a statistically significant difference between an interventional strategy and conservative medical therapy with respect to all-cause mortality (15.1% vs 12.1%) and the rate of cardiac death or myocardial infarction (15.9% vs 12.2%).

Data from the Treat Angina with Aggrastat and Determine Cost of Therapy with an Invasive or Conservative Strategy–Thrombolysis in Myocardial Infarction (TACTICS-TIMI) 18 trial showed that the primary endpoint of death, myocardial infarction, or rehospitalization at 6 months occurred in 19.4% of the conservative group and 15.9% of the invasive group, with death or myocardial infarction occurring in 9.5% and 7.3%, respectively.^[35]

In this study, patients who had a positive troponin test result, those who had ST-segment changes, those who were older than 65 years, and, especially, those who were women with elevated brain natriuretic peptide (BNP) and C-reactive protein (CRP) levels derived particular benefit from an early invasive strategy.^[35]

The Early Invasive versus Selectively Invasive Management for Acute Coronary Syndromes (ICTUS) trial, which compared an early invasive strategy (angiography and revascularization within 48 hours) with a selective invasive strategy (medical stabilization with angiography and revascularization in refractory cases) in 1200 Dutch patients, demonstrated no statistical difference in mortality or the composite endpoint (death, nonfatal myocardial infarction, or rehospitalization for anginal symptoms within 1 year).^[36]

At 3 years’ follow-up, the ICTUS trial documented a trend toward significance favoring the selective invasive strategy for the combined endpoints (30% early invasive vs 26% selective invasive) but reported no difference in all-cause mortality and cardiac death.

On the basis of these results, the ACC/AHA guidelines recommended that an early (within 48 h) invasive approach should be used to treat patients presenting with the following higher-risk features^[37] :

• PCI or CABG in the past 6 months
• New ST-segment depression
• Elevated cardiac biomarkers
• Recurrent angina at rest or low level of activity
• LV systolic function of less than 40%
• TIMI score greater than 2

In lower-risk patients (TIMI score ≤2), evidence has shown that invasive therapy and medical therapy provide similar outcomes.

PCI in acute myocardial infarction (STEMI)

The recognition that intracoronary thrombosis is the primary mechanism of vessel occlusion in AMI and that prompt restoration of vessel patency provides significant clinical benefit has led to the development of aggressive new treatments for this disorder.

Thrombolytic therapies, such as front-loaded tissue plasminogen activator (t-PA), reteplase (r-PA), and tenecteplase (TNK), open approximately 80% of infarct-related vessels within 90 minutes, but only 50% will have normal (TIMI grade 3) flow. In addition, 10% of vessels opened by thrombolysis either become reoccluded or are the source for recurrent symptoms of angina. Because of these limitations, several randomized trials have evaluated mechanical revascularization (so-called primary angioplasty) in the setting of AMI.

An analysis of 23 trials confirms the superiority of primary angioplasty over fibrinolytic therapy in terms of adverse events and mortality reduction, both in the short term and in the long term. Overall, primary PCI was associated with significant reductions in death, recurrent myocardial infarction, reinfarction, and the combined endpoint of death, myocardial infarction, and stroke.

When patients are transferred from outside hospitals, primary angioplasty is often preferred to onsite fibrinolytic therapy for patients with any of the following:

Expected door-to-balloon time less than 90 minutes and symptom duration less than 3 hours

• Symptom duration more than 3 hours
• Cardiogenic shock
• Contraindications to fibrinolytic therapy
• Age older than 75 years

The use of thrombolytic therapy followed by referral for intentional PCI (facilitated PCI) has not been shown to be superior to primary PCI and may actually worsen outcomes with increased risk of stroke and bleeding (ASSENT 4).

There is now some evidence to suggest that early use of GPIIb/IIIa inhibitors may help achieve earlier infarct vessel patency and better outcomes during PCI. Whether this is so for all of these agents is being assessed in several studies.

Intracoronary abciximab administration, when compared with the intravenous standard route, can improve short-term clinical outcomes in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary PCI. A pooled analysis of individual data of 1,198 patients enrolled in five trials showed that intracoronary abciximab administration, in comparison to intravenous abciximab, significantly reduced the risk of the composite of death and reinfarction and death. After correction for baseline differences, there were no significant differences in target vessel revascularization or the risk of reinfarction.^[38]

A meta-analysis has shown that abciximab is associated with a 46% reduction in death and reinfarction in primary PCI patients, and the AHA/ACC STEMI guidelines^[37] currently recommend early use of abciximab in these patients. When fibrinolytic therapy is given but fails to produce ST resolution, immediate PCI (rescue PCI) is recommended.^{[39, 40]}

Some of the most important considerations in providing effective primary PCI relate to the logistical issues and barriers that are known to exist. The PCI system or network, ambiguity of leadership and organization, protocols/care, pathways/interfacility transfer, and reimbursement issues are the main areas of contention.

Studies of the US primary PCI sites that are considered the best—that is, those sites that consistently deliver door-to-balloon times of 90 minutes or less (currently accounting for about 5% of the US myocardial infarction population)—have identified the following as being the key determinants of shorter door-to-balloon times:

• Electrocardiography (ECG) being performed within 10 minutes
• The emergency department independently making the decision to engage the catheterization laboratory team
• Interdisciplinary teamwork

The key factor for effective primary PCI is timely reperfusion therapy. Using data from the Centers for Medicare and Medicaid Services (CMS), one study examined the door-in/door-out (DIDO) time in the initial hospital for patients who transferred to a second hospital for primary angioplasty; only 1343 (9.7%) had a DIDO time within 30 minutes, and 4267 (31.0%) had a DIDO time longer than 90 minutes.^[41] This suggests that efforts should be made to enhance the care of STEMI patients presenting to hospitals without interventional cardiology facilities.

Studies using the National Registry of Myocardial Infarction (NRMI) data have shown that shortening door-to-balloon time to less than 90 minutes is associated with a reduction in mortality. In certain situations, timely reperfusion may be best achieved with fibrinolytic therapy if access to primary PCI is likely to be delayed.

Rathore et al, in a prospective cohort study of 43,801 patients enrolled in the ACC National Cardiovascular Data Registry in 2005-2006, found that any delay in primary PCI after a patient with STEMI arrives at the hospital is associated with higher mortality.^[42]

In this study, longer door-to-balloon times were associated with a higher adjusted risk of in-hospital mortality, in a continuous nonlinear fashion (30 min = 3%, 60 min = 3.5%, 90 min = 4.3%, 120 min = 5.6%, 150 min = 7%, 180 min = 8.4%).^[42] A reduction in door-to-balloon time from 90 minutes to 60 minutes was associated with a 0.8% reduction in mortality, and a reduction from 60 minutes to 30 minutes was associated with a 0.5% reduction in mortality.

Brodie et al, analyzing the Controlled Abciximab and Device Investigation to Lower Late Angioplasty Complications (CADILLAC) trial and the Harmonizing Outcomes with Revascularization and Stents in Acute Myocardial Infarction (HORIZONS-AMI) trial, found that a door-to-balloon time of less than 90 minutes was associated with a lower mortality in patients with STEMI^[43] ; however, the benefit was primarily noted in patients with who presented with less than 90 minutes of symptoms.

In this study, a door-to-balloon time shorter than 90 minutes was associated with similar relative risk reductions in high-risk and low-risk patients, although the absolute benefit was greatest in high-risk patients.^[43]

From a procedural perspective, because primary PCI involves a thrombotic plaque, there is a potential risk of additional complications exists, especially no-reflow and distal embolization. These patients should achieve final TIMI 3 flow. Stenting plus GPIIb/IIIa inhibition has been shown to improve outcomes, reducing target vessel revascularization and myocardial infarction rates in comparison with balloon angioplasty.

The use of adjunctive antithrombotic approaches, including early GPIIb/IIIa inhibition use and mechanical thrombectomy, has shown benefit. Important issues remain as to which type of stent to use (drug-eluting or bare-metal) and whether adjusting the timing of antiplatelet therapy (both intravenous [IV] and oral) might provide better outcomes for certain patients.

Stone et al studied the safety and efficacy of drug-eluting stents and bare-metal stents in patients with STEMI who underwent primary PCI. Patients (n = 3006) were assigned in a 3:1 ratio to receive paclitaxel-eluting stents or otherwise identical bare-metal stents. The paclitaxel-eluting stents significantly reduced angiographic evidence of restenosis and recurrent ischemia necessitating repeat revascularization at 12-month follow-up. The rates of death and stent thrombosis were similar for the 2 groups.^[12]

General comparison of PCI and CABG

A 2007 research review by the Agency for Healthcare Research and Quality (AHRQ) examined 23 randomized controlled trials of PCI versus CABG (including a total of 9963 patients) and found that short-term survival was high for both procedures and did not differ significantly between them.^[44] However, freedom from procedural stroke was significantly higher after PCI than after CABG.

In the AHRQ study, there was no significant difference in long-term survival (1-5 years of follow-up) between the 2 procedures.^[44] However, survival was significantly better after PCI in patients with single-vessel disease that did not involve the proximal LAD and was significantly better after CABG in patients with extensive triple-vessel or left main artery disease.

Long-term freedom from angina was significantly greater after CABG than after PCI, as was the need for repeat coronary revascularization procedures.^[44] The use of coronary artery stents narrowed, but did not close, the gap between PCI and CABG in repeat revascularization procedures. Although PCI initially was less costly than CABG, the cost difference narrowed substantially over time, to roughly 5%.