[Deterministic record linkage with indirect identifiers: data of the Berlin Myocardial Infarction Registry and the AOK Nordost for patients with myocardial infarction]

AIM OF THE STUDY

How can 2 pseudonymised data sets be linked? Using the example of data from the Berlin Myocardial Infarction Registry and from a German sickness fund (AOK Nordost) we will demonstrate how record linkage can be achieved without personal identifiers.

METHODS

In different steps the method of deterministic record linkage with indirect identifiers: age, sex, hospital admission date and time, will be explained.

RESULTS

We were able to show that 80.6% of the expected maximum number of patients were matched with our approach. As a result we had no duplicate matches in the linkage process, where one AOK patient was linked to 2 or more BMIR patients or vice versa. The matching variables produced enough uniqueness to be used as indirect patient identifiers.

CONCLUSION

Deterministic record linkage with the following indirect indicators: age, sex, hospital admission date and time was possible in our study of patients with myocardial infarction in a circumscribed geographical region, which limited the number of cases and avoided mismatches.

The relationship between hospital or operator volume and outcomes of coronary patients undergoing percutaneous coronary interventions

The relationship between volume and outcome in medicine has been intensively investigated in the last few decades. The large amount of accumulated data demonstrates that for many surgical or non-surgical procedures and medical conditions, patients being treated in high-volume hospitals or by high-volume physicians have lower mortality rates and better quality of life compared to those treated by low-volume hospitals or by low-volume physicians. Although the degree of the relationship between high volume and better outcome varies, it is persistent across a wide range of procedures and conditions. Percutaneous coronary interventions (PCIs) have an important impact on public health, given the frequency of coronary heart disease for which these procedures are performed. Studies carried out before and after the advent of stents on the relationship between volume and outcome for PCIs have almost consistently reported that performance of PCIs in high-volume institutions or by high-volume operators is associated with improved outcomes for patients, regardless of the specific indication for PCI. For those procedures for which a relationship between high volume and better outcome has been clearly demonstrated, patients as well as their referring physicians should be informed that patients can benefit both in terms of reduced mortality and improved quality of life if they are treated by high-volume health care providers. Consequently, for these procedures, a health care policy aiming at their concentration in high-volume institutions should be strongly considered.

A randomized trial comparing phosphorylcholine-coated stenting with balloon angioplasty as well as abciximab with placebo for restenosis reduction in small coronary arteries

OBJECTIVE

The objective of this randomized trial was to assess the antirestenotic effects of phosphorylcholine (PC)-coated stents as well as of abciximab in small coronary arteries when compared with percutaneous transluminal coronary angioplasty (PTCA) and placebo respectively.

BACKGROUND

Stent coating with PC has been shown to reduce protein absorption and platelet activation which may reduce the risk of restenosis. Furthermore, on the basis of nondedicated studies abciximab is believed to reduce the risk of restenosis after coronary interventions.

METHODS

A total of 502 patients with lesions situated in small coronary arteries (vessel diameter </=2.5 mm) were randomly assigned to be treated with either PC-coated stents (n = 253) or PTCA (n = 249) and with either abciximab (n = 251) or placebo (n = 251) with the use of a 2 x 2 factorial design. All patients were pretreated with 600 mg clopidogrel. The primary end-point was the incidence of angiographic restenosis (>/=50% diameter stenosis) at follow-up; death or myocardial infarction, and target vessel revascularization (TVR), were assessed as secondary end-points.

RESULTS

Angiographic restenosis did not differ between patients treated with PC-coated stents or with PTCA (39.0% vs. 34.2%; P = 0.30) and between patients receiving abciximab or placebo (39.3% vs. 34.3%; P = 0.29). Similarly, the need for TVR at 1-year follow-up did not differ between patients receiving PC-coated stents or PTCA (20.2% vs. 20.5%; P = 0.98) as well as between patients treated with abciximab or placebo (18.7% vs. 21.9%; P = 0.44).

CONCLUSIONS

PC-coated stents and abciximab failed to reduce the incidence of angiographic restenosis after percutaneous coronary intervention of small coronary arteries. These data strengthen the belief that future studies on prevention of restenosis in small coronary arteries should focus on drug-eluting stents.

A randomized trial comparing the hand-mounted JoStent with the premounted Multi-Link Duet stent in patients with coronary artery disease

The objective of this multicenter randomized study was to compare the angiographic and clinical results achieved 1 year after coronary placement of two stent models: the hand-mounted JoStent and the premounted Multi-Link Duet stent. We included 505 patients who were randomly assigned to receive either the hand-mounted JoStent (n = 252) or the premounted Multi-Link Duet stent (n = 253). The primary endpoint of the study, late lumen loss, measured 1.12 mm in the JoStent group and 1.17 mm in the Multi-Link Duet group. These values were statistically equivalent (P = 0.02 from the equivalence test). No significant difference was observed in the incidence of restenosis, 24.2% in the JoStent and 25.2% in the Multi-Link Duet stent group, and target vessel revascularization, 13.9% in the JoStent and 15.4% in the Multi-Link Duet patients. In conclusion, the hand-mounted JoStent and the premounted Multi-Link Duet stent enable excellent procedural success rates and equally favorable 1-year angiographic and clinical outcomes.

Incidence of thrombotic occlusion and major adverse cardiac events between two and four weeks after coronary stent placement: analysis of 5,678 patients with a four-week ticlopidine regimen

OBJECTIVES

We attempted to make a comprehensive assessment of the risk of stent failure (death, myocardial infarction or angiographically documented occlusion), differentiating early (first and second weeks) and late (third and fourth weeks) events.

BACKGROUND

The risk of stent failure decreases rapidly within the first week. It has been suggested that the risk rate for late events is close to 0% and that the thienopyridine regimen (ticlopidine or clopidogrel) could be safely reduced from four to two weeks, minimizing the risk of hematological complications.

METHODS

We analyzed 5,678 patients with successful coronary stent placement and a four-week ticlopidine regimen.

RESULTS

The rate of stent failure was 2.5% at four weeks, with 112 early (2.0%) and 30 late events (0.5%). Multivariate analysis identified different risk factors for early versus late events. While variables on stenosis severity and procedural results that can be influenced by the operator were identified as independent risk factors for early events (percent stenosis before and after the procedure, residual dissection, length of stented segment), more clinical variables were associated with late events (age, reduced left ventricular function, systemic hypertension as a protective factor). The late-event rate was <0.1% in the absence of these factors, but it was 2.5% with all three risk factors present.

CONCLUSIONS

The risk of late stent failure is low with a four-week ticlopidine regimen. However, high-risk subgroups have a risk of 2.5%. As this rate is presumably higher if thienopyridines are discontinued after two weeks, these data suggest that a risk stratification to a two- or four-week regimen is preferable to a general reduction.

Intracoronary stenting and angiographic results: strut thickness effect on restenosis outcome (ISAR-STEREO) trial

BACKGROUND

Increased thrombogenicity and smooth muscle cell proliferative response induced by the metal struts compromise the advantages of coronary stenting. The objective of this randomized, multicenter study was to assess whether a reduced strut thickness of coronary stents is associated with improved follow-up angiographic and clinical results.

METHODS AND RESULTS

A total of 651 patients with coronary lesions situated in native vessels >2.8 mm in diameter were randomly assigned to receive 1 of 2 commercially available stents of comparable design but different thickness: 326 patients to the thin-strut stent (strut thickness of 50 microm) and 325 patients to the thick-strut stent (strut thickness of 140 microm). The primary end point was the angiographic restenosis (>/=50% diameter stenosis at follow-up angiography). Secondary end points were the incidence of reinterventions due to restenosis-induced ischemia and the combined rate of death and myocardial infarctions at 1 year. The incidence of angiographic restenosis was 15.0% in the thin-strut group and 25.8% in the thick-strut group (relative risk, 0.58; 95% CI, 0.39 to 0.87; P=0.003). Clinical restenosis was also significantly reduced, with a reintervention rate of 8.6% among thin-strut patients and 13.8% among thick-strut patients (relative risk, 0.62; 95% CI, 0.39 to 0.99; P=0.03). No difference was observed in the combined 1-year rate of death and myocardial infarction.

CONCLUSIONS

The use of a thinner-strut device is associated with a significant reduction of angiographic and clinical restenosis after coronary artery stenting. These findings may have relevant implications for the currently most widely used percutaneous coronary intervention.

Usefulness of intracoronary brachytherapy for in-stent restenosis with a 188Re liquid-filled balloon

The objective of this randomized pilot trial with 21 patients was to evaluate the effectiveness of a rhenium-188 liquid-filled balloon system to prevent recurrent restenosis after percutaneous transluminal coronary angioplasty for in-stent restenosis. A significant benefit from brachytherapy was seen at 6-month repeat angiography, as well as during the clinical follow-up of 12 months.

Sustained benefit over four years from an initial combined antiplatelet regimen after coronary stent placement in the ISAR trial. Intracoronary Stenting and Antithrombotic Regimen

Combined antiplatelet therapy after coronary stent placement is superior to anticoagulation with respect to early outcome. It is unclear if this benefit is maintained during long-term follow-up. This study reports on the 4-year clinical outcome of patients randomized in the Intracoronary Stenting and Antithrombotic Regimen trial. In the Intracoronary Stenting and Antithrombotic Regimen trial, 517 patients were randomized after successful placement of Palmaz-Schatz stents: 257 to aspirin and ticlopidine, and 260 to aspirin and phenprocoumon. Ticlopidine and phenprocoumon were given for 4 weeks. At 30 days, patients with ticlopidine had significantly fewer adverse cardiac events (1.6% vs 6.2%; p = 0.007), nonfatal myocardial infarction (0.8% vs 3.5%; p = 0.034), and target vessel revascularization procedures (1.2% vs 5.4%; p = 0.007). At 4 years, rates for any adverse cardiac events were 22.6% versus 28.5% (p = 0.078), for nonfatal myocardial infarction 0.9% versus 5.8% (p = 0.003), and for target vessel revascularization 18.3% versus 22.7% (p = 0.21). The absolute difference in event rates (4.6% after 30 days) was maintained after 4 years (5.9%). Event rates beyond day 30 were not significantly different (21.1% vs 22.5%; p = 0.78), nor were the rates beyond the first year, which were very low (5.2% vs 3.6%; p = 0.50). This study shows that the benefit of combined antiplatelet therapy evident after 30 days is maintained after 4 years. Independent of the initial regimen, rates of adverse cardiac events are low beyond the first year.

Restenosis after coronary placement of various stent types

Coronary stent implantation is being performed in an increasing number of patients with a wide spectrum of clinical and lesion characteristics. A variety of stent designs are now available and continuous efforts are being made to improve the stent placement procedure. The objective of this study was to perform a comprehensive analysis of the relation between clinical, lesion, and procedural factors, and restenosis after intracoronary stenting in a large and unselected population of patients. A consecutive series of 4,510 patients with coronary stent placement was analyzed. Exclusion criteria were only a failed procedure and an adverse outcome within the first month after the intervention. Follow-up angiography was performed in 80% of patients at 6 months. Clinical, lesion, and procedural data from all 3,370 patients (4,229 stented lesions) with follow-up angiography were analyzed in a logistic regression model for restenosis (> or =50% diameter stenosis). Clinical factors contributed to the predictive power of the model much less than lesion and procedural factors. The strongest risk factor for restenosis was a small vessel size, with a 79% increase in the risk for a vessel of 2.7 mm versus a vessel of 3.4 mm in diameter. Stent design was the second strongest factor; the incidence of restenosis ranged from 20.0% to 50.3% depending on the stent type implanted. In conclusion, this study demonstrates the predominant role of lesion and procedural factors in determining the occurrence of restenosis after coronary stent placement. Among these factors, stent design appears to play a particularly important role in the hyperplastic response of the vessel wall.

Influence of stent design on 1-year outcome after coronary stent placement: a randomized comparison of five stent types in 1,147 unselected patients

The objective of this randomized trial was to assess whether differences in stent design are translated in different clinical outcomes in patients undergoing coronary stent placement. This multicenter randomized trial included 1,147 patients who were randomly assigned to receive one of five types of stainless steel stents: Inflow, MULTI-LINK, NIR, Palmaz-Schatz, and PURA-A stent. Primary endpoint of the study was event-free survival at 1 year. Event-free survival at 1 year was significantly different between the groups (P = 0.014), ranging from 69.4% to 82.4%. Similarly, freedom from myocardial infarction was also significantly different (P = 0.022), with values between 88.2% and 95.2%. Diameter stenosis at 6 months varied from 38.1% +/- 25.0% to 45.6% +/- 27.7% (P = 0. 046), late lumen loss ranged from 1.01 +/- 0.70 mm to 1.20 +/- 0.82 mm (P = 0.085), and the incidence of restenosis varied between 25.3% and 35.9% (P = 0.145). Thus, stent design has a significant impact on the long-term results after coronary stent placement.

Increased risk of restenosis after placement of gold-coated stents: results of a randomized trial comparing gold-coated with uncoated steel stents in patients with coronary artery disease

BACKGROUND

Gold is a highly biocompatible material. Experimental evidence suggests that coating the stent with a gold layer may have a beneficial influence. In this randomized trial, we assessed whether gold-coated stents were associated with a better clinical and angiographic outcome after coronary placement.

METHODS AND RESULTS

Patients with symptomatic coronary artery disease were randomly assigned to receive either a gold-coated Inflow stent (n = 367) or an uncoated Inflow stainless steel stent (n = 364) of identical design. Follow-up angiography was routinely performed at 6 months. The primary end point of the study was the occurrence of any adverse clinical event (death, myocardial infarction, or target-vessel revascularization) during the first year after stenting. At 30 days, there was no significant difference in the combined incidence of adverse events, with 7.9% in the gold-stent group versus 5.8% in the steel-stent group (P = 0.25). The incidence of angiographic restenosis (> or =50% diameter stenosis) was 49.7% in the gold-stent group and 38.1% in the steel-stent group (P = 0.003). One-year survival free of myocardial infarction was 88.6% in the gold-stent group and 91.8% in the steel-stent group (P = 0.14). One-year event-free survival was significantly less favorable in the gold-stent group (62.9% versus 73.9% in the steel-stent group; P = 0.001).

CONCLUSIONS

Coating steel stents with gold had no significant influence on the thrombotic events observed during the first 30 days after the intervention. However, gold-coated stents were associated with a considerable increase in the risk of restenosis over the first year after stenting.

Prognostic value of the modified american college of Cardiology/American heart association stenosis morphology classification for long-term angiographic and clinical outcome after coronary stent placement

Background-The modified American College of Cardiology/American Heart Association (ACC/AHA) lesion morphology criteria are predictive of early outcome after various coronary catheter interventions. Their potential prognostic value after stent implantation and, in particular, for restenosis and long-term clinical outcome has not been studied. We assessed the prognostic value of the modified ACC/AHA criteria for the long-term angiographic and clinical outcome of patients after coronary stenting. Methods and Results-This study includes 2944 consecutive patients with symptomatic coronary artery disease treated with coronary stent placement. Modified ACC/AHA lesion morphology criteria were used to qualitatively assess the angiograms; type A and B1 lesions were categorized as simple, and type B2 and C lesions were designated complex. Primary end points were angiographic restenosis and 1-year event-free survival. Restenosis rate was 33.2% in complex lesions and 24.9% in simple lesions (P<0.001). It was 21. 7% for type A, 26.3% for type B1, 33.7% for type B2, and 32.6% for type C lesions. One-year event-free survival was 75.6% for patients with complex lesions and 81.1% for patients with simple lesions (P<0. 001). It was 85.2% for patients with type A, 79.4% for type B1, 75. 9% for type B2, and 75.2% type C lesions. The higher risk for restenosis and an adverse outcome associated with complex lesions was also maintained after multivariate adjustment for other clinical and angiographic characteristics. Conclusions-The modified ACC/AHA lesion morphology scheme has significant prognostic value for the outcome of patients after coronary stent placement. Lesion morphology is able to influence the restenosis process and thus the entire 1-year clinical course of these patients.

Influence of balloon pressure during stent placement in native coronary arteries on early and late angiographic and clinical outcome: A randomized evaluation of high-pressure inflation

BACKGROUND

High-pressure dilatation is considered a better stent placement strategy, but this has not yet been proved by appropriately designed studies. The objective of this randomized trial was to assess the role of high-pressure dilatation in the early and late outcome of patients undergoing coronary stent placement.

METHODS AND RESULTS

Consecutive patients with coronary stent placement were randomly assigned to high- (15 to 20 atm, 468 patients) or low- (8 to 13 atm, 466 patients) balloon-pressure dilatation. The primary end point of the study was the event-free survival at 1 year. Secondary end points were the incidence of stent thrombosis at 30 days and angiographic restenosis (>/=50% diameter stenosis) at 6 months. The incidence of stent thrombosis was 1.7% in the high-pressure and 1.9% in the low-pressure group (relative risk 0.89; 95% CI 0.30 to 2.56). During the first 30 days, although there was no significant difference in the incidence of Q-wave myocardial infarction, the incidence of non-Q-wave infarction was 6.4% in the high-pressure and 3.4% in the low-pressure group (relative risk 1. 87; 95% CI 1.02 to 3.42). The restenosis rate was 30.4% in the high-pressure and 31.4% in the low-pressure group (relative risk 0. 97; 95% CI 0.75 to 1.26). Event-free survival at 1 year was not significantly different between the groups, with 78.8% in high-pressure patients and 75.5% in patients assigned to low-pressure dilatation (hazard ratio 0.85; 95% CI 0.65 to 1.11).

CONCLUSIONS

The systematic use of high-balloon-pressure inflation (15 to 20 atm) during coronary stent placement is not associated with any significant influence on the 1-year outcome of patients undergoing this intervention.

Clinical and angiographic outcome after stent placement for chronic coronary occlusion

A consecutive series of 132 patients with total chronic coronary occlusions were compared with 1,966 patients with stenotic lesions in terms of angiographic and clinical outcome. We concluded that patients with chronically occluded coronary lesions present a higher rate of target lesion revascularizations and angiographic restenosis than patients with stenotic lesions.

Intracoronary stenting and risk for major adverse cardiac events during the first month

BACKGROUND

Our rationale for this study was to analyze the risk for procedural failure of attempted stenting and the risk for major adverse cardiac events (MACE) after success and to develop a risk stratification protocol for successful procedures.

METHODS AND RESULTS

Stenting was attempted in 2894 procedures during the 5-year study period (success in 98.3% of 3815 lesions). After failure, the MACE rate was 42.6%. The risk for failure was higher for lesions in the left circumflex coronary artery or in venous bypass grafts and after an acute occlusion before stenting; it increased with stenosis length or grade and decreased with vessel size and growing institutional experience in stenting. After success, death occurred in 0.8%, death or myocardial infarction in 2.0%, and any MACE in 3.6%. Independent risk factors for MACE were older age, diabetes, acute myocardial infarction, unstable angina, impaired left ventricular function, residual dissections, stent overlap, longer stented segments, and a postprocedural regimen without ticlopidine. Procedural factors were substantially stronger predictors than operator-independent variables available before procedures. Overall, the risk declined after the first 3 days. Two major factors exhibited time-dependent variations of their influence: while residual dissections were the dominant risk factor within the first 3 days with a reduction after that, no protective effect of ticlopidine could be identified before day 3. From these results, we derived a risk stratification protocol for individual procedures.

CONCLUSIONS

These results underscore the importance of optimal angiographic results and the need for antiplatelet regimens with immediate onset. Our risk stratification protocol may guide individual postprocedural care and allow us to compare risk profiles of different study populations and to devise quality control programs for stenting.

Interlesion dependence of the risk for restenosis in patients with coronary stent placement in in multiple lesions

BACKGROUND

Little is known about the behavior with regard to restenosis of multiple lesions within the same patient treated with intracoronary stenting. Our objective was to test the hypothesis that there is an intrapatient dependence of restenosis between lesions.

METHODS AND RESULTS

Quantitative analysis was carried out on angiograms obtained before, immediately after, and at 6 months after coronary stent placement in 1734 lesions in 1244 patients. We used a specialized logistic regression that not only accounts for intraclass correlation but also quantifies it in the form of odds ratio (OR) as the change in risk of a lesion to develop restenosis if another companion lesion had restenosis. The model was based on 23 patient- and lesion-related variables with binary restenosis (diameter stenosis > or =50%) as end point. The overall restenosis rate was 27.5%: 24.4% for single-lesion, 28.6% for double-lesion, and 33.8% for > or =3-lesion interventions. After adjustment for the influence of significant factors (hypercholesterolemia, systemic arterial hypertension, diabetes mellitus, previous PTCA, ostial lesion, location in left anterior descending coronary artery, number of stents placed, vessel size, stenosis severity, balloon-to-vessel ratio, and final result), the analysis found a significant intrapatient correlation, OR 2.5 (1.8 to 3.6). This means that in patients with multilesion interventions, the risk of a lesion to develop restenosis is 2.5 times higher if a companion lesion has restenosis, independently of the presence or absence of analyzed patient risk factors (eg, diabetes).

CONCLUSIONS

This study demonstrates that there is a dependence of restenosis between coronary lesions in patients who undergo a multilesion intervention. The likelihood of restenosis for a lesion is higher when another companion lesion has also developed restenosis. Other, as yet unidentified patient factors may be the source of this intrapatient correlation of restenosis.

Bimodal distribution of angiographic measures of restenosis six months after coronary stent placement

BACKGROUND

Restenosis has been perceived as the tail end of a normal distribution of the response of the vessel to the intervention. However, recent studies have described a bimodal distribution for de novo lesions after percutaneous transluminal coronary angioplasty. This finding suggests that some lesions may be more susceptible for restenosis. Whether this holds true for a wider spectrum of lesions undergoing stent placement is not yet known. The present study analyzes the frequency distribution of angiographic indexes of restenosis 6 months after coronary stent implantation.

METHODS AND RESULTS

Quantitative angiographic evaluation was performed in 1084 lesions of 1084 patients before, immediately after, and 6 months after successful Palmaz-Schatz stent placement; this represented 80.4% of patients eligible for follow-up angiography. Principal end points of the analysis were angiographic indexes of restenosis at 6 months. Twenty-two lesions that became totally occluded at follow-up were excluded from most parts of the analysis. Diameter stenosis, minimal luminal diameter (MLD), and lumen loss at 6 months did not follow a normal pattern; the bimodal pattern was demonstrated through deconvolution that yielded two separate normal components delineating two lesion populations, which developed distinctively different degrees of lumen renarrowing. The first and larger subgroup of lesions, which was less prone to restenosis, was centered around a mean value of 27% for diameter stenosis and 2.19 mm for MLD, whereas the second subgroup, with a greater tendency for restenosis, was situated around a mean value of 68% for diameter stenosis and 0.76 mm for MLD. The intersection point between the two theoretical normal distribution components was 53.5% for diameter stenosis and 1.09 mm for MLD at follow-up.

CONCLUSIONS

Frequency-distribution curves of angiographic indexes of restenosis after coronary stent placement have a bimodal pattern, suggesting the existence of two distinct populations with different propensity to restenosis. These findings may encourage future efforts for the timely identification of the subset with a higher risk as the target of specific antirestenotic strategies.

Predictive factors of restenosis after coronary stent placement

OBJECTIVES

The objective of this study was to identify clinical, lesional and procedural factors that can predict restenosis after coronary stent placement.

BACKGROUND

Coronary stent placement reduces the restenosis rate compared with that after percutaneous transluminal coronary angioplasty (PTCA). However, restenosis remains an unresolved issue, and identification of its predictive factors may allow further insight into the underlying process.

METHODS

All patients with successful coronary stent placement were eligible for this study unless they had had a major adverse cardiac event during the 1st 30 days after the procedure. Of the 1,349 eligible patients (1,753 lesions), follow-up angiography at 6 months was performed in 80.4% (1,084 patients, 1,399 lesions). Demographic, clinical, lesional and procedural data were prospectively recorded and analyzed for any predictive power for the occurrence of late restenosis after stenting. Restenosis was evaluated by using three outcomes at follow-up: binary restenosis as a diameter stenosis > or =50%, late lumen loss as lumen diameter reduction and target lesion revascularization (TLR) as any repeat PTCA or coronary artery bypass surgery involving the stented lesion.

RESULTS

Multivariate analysis demonstrated that diabetes mellitus, placement of multiple stents and minimal lumen diameter (MLD) immediately after stenting were the strongest predictors of restenosis. Diabetes increased the risk of binary restenosis with an odds ratio (OR) [95% confidence interval] of 1.86 [1.56 to 2.16] and the risk of TLR with an OR of 1.45 [1.11 to 1.80]. Multiple stents increased the risk of binary restenosis with an OR of 1.81 [1.55 to 2.06] and that of TLR with an OR of 1.94 [1.66 to 2.22]. An MLD <3 mm at the end of the procedure augmented the risk of binary restenosis with an OR of 1.81 [1.55 to 2.06] and that of TLR with an OR of 2.05 [1.77 to 2.34]. Classification and regression tree analysis demonstrated that the incidence of restenosis may be as low as 16% for a lesion without any of these risk factors and as high as 59% for a lesion with a combination of these risk factors.

CONCLUSIONS

Diabetes, multiple stents and smaller final MLD are strong predictors of restenosis after coronary stent placement. Achieving an optimal result with a minimal number of stents during the procedure may significantly reduce this risk even in patients with adverse clinical characteristics such as diabetes.

Restenosis after coronary stent placement and randomization to a 4-week combined antiplatelet or anticoagulant therapy: six-month angiographic follow-up of the Intracoronary Stenting and Antithrombotic Regimen (ISAR) Trial

BACKGROUND

Platelets and mural thrombus at the lesion site may play a key role in initiating the restenosis process after coronary interventions. The ISAR Trial provides a comparison of the outcomes of patients randomized to two different antithrombotic regimens administered for 4 weeks after successful coronary stent placement: combined antiplatelet therapy (aspirin plus ticlopidine) or a conventional anticoagulant regimen (phenprocoumon with initial overlapping heparin plus aspirin). Within the first 4 weeks after stent placement, combined antiplatelet therapy has been associated with a significant reduction of ischemic complications. In the present study, we examined whether combined antiplatelet therapy administered for 4 weeks after stent placement is able to reduce the process of restenosis at 6 months.

METHODS AND RESULTS

Of 517 patients initially randomized, 496 were eligible for 6-month angiographic follow-up. Scheduled angiography was performed in 432 of the eligible patients (87.1%), 216 in each group. In a comparison of the two groups, there were no significant differences in clinical and procedural variables or in qualitative and quantitative lesion characteristics before and after stenting. At 6 months, minimal luminal diameter was 1.95+/-0.86 mm in the group with initial combined antiplatelet therapy and 1.90+/-0.87 mm in the group with initial anticoagulant therapy (P=.55). Late lumen loss was 1.10+/-0.81 and 1.15+/-0.75 mm (P=.54), and the restenosis rate was 26.8% and 28.9%, respectively (P=.70). Target lesion revascularization rate was 14.6% in the antiplatelet therapy group and 15.6% in the anticoagulant therapy group (P=.85).

CONCLUSIONS

This study shows that combined antiplatelet therapy (aspirin plus ticlopidine) administered for 4 weeks after coronary Palmaz-Schatz stent placement does not result in a detectable benefit for the prevention of restenosis compared with conventional anticoagulant therapy (phenprocoumon with initial overlapping heparin plus aspirin).

Major benefit from antiplatelet therapy for patients at high risk for adverse cardiac events after coronary Palmaz-Schatz stent placement: analysis of a prospective risk stratification protocol in the Intracoronary Stenting and Antithrombotic Regimen (ISAR) trial

BACKGROUND

The Intracoronary Stenting and Antithrombotic Regimen (ISAR) Trial is a randomized study in which antiplatelet therapy is compared with anticoagulant therapy after coronary stent placement, showing a significantly lower rate of noncardiac and cardiac events with antiplatelet therapy. The present study is a report of the analysis of a prospective risk stratification protocol in the ISAR Trial and the association with the incidence of adverse cardiac events and stent vessel occlusion.

METHODS AND RESULTS

In all 517 patients randomized in the ISAR Trial, risk stratification was done with a list of 18 clinical, procedural, and angiographic variables: 165 patients with two or fewer criteria were classified as low risk, 148 patients with three criteria were classified as intermediate risk, and 204 patients with four or more criteria were classified as high risk. Within a 30-day follow-up, cardiac event rate (death, myocardial infarction, repeat intervention) was 6.4% for high-risk, 3.4% for intermediate-risk, and 0% for low-risk patients (P<.01). Stent vessel occlusion occurred in 5.9%, 2.7%, and 0%, respectively (P<.01). There was no significant difference between anticoagulant and antiplatelet therapy in the low- and intermediate-risk groups. In high-risk patients, however, the cardiac event rate was 12.6% with anticoagulant therapy and 2.0% with antiplatelet therapy (P=.007), and the rate of stent vessel occlusion was 11.5% and 0%, respectively (P<.001).

CONCLUSIONS

This risk stratification protocol can help to identify patients at risk for adverse cardiac events and stent vessel occlusion. Patients in the high-risk group had the most benefit from antiplatelet therapy. These data suggest that antiplatelet therapy is the therapy of choice after coronary stenting specifically for patients with acute ischemic syndromes, difficult procedures, or suboptimal final results.

Coronary stent placement in patients with acute myocardial infarction: comparison of clinical and angiographic outcome after randomization to antiplatelet or anticoagulant therapy

OBJECTIVES

The Intracoronary Stenting and Antithrombotic Regimen (ISAR) trial is a randomized comparison of combined antiplatelet with anticoagulant therapy after coronary Palmaz-Schatz stent placement. The objective of this study was to compare early and late clinical and angiographic outcome in a subgroup of patients with stent placement for acute myocardial infarction.

BACKGROUND

Stenting has become a treatment option for acute myocardial infarction, but it is not known which antithrombotic regimen is more adequate after stent implantation.

METHODS

One hundred twenty-three patients with successful stenting after acute myocardial infarction were randomized to receive aspirin plus ticlopidine (n = 61) or intense anticoagulant therapy (n = 62). Six-month repeat angiography was performed in 101 (86.3%) eligible patients.

RESULTS

During the first 30 days after stenting, patients with antiplatelet therapy had a significantly lower clinical event rate (3.3% vs. 21.0%, p = 0.005) and stent vessel occlusion rate (0% vs. 9.7%, p = 0.03) and a trend to fewer cardiac events (1.6% vs. 9.7%, p = 0.12). After 6 months, the survival rate free of recurrent myocardial infarction was higher in patients with antiplatelet therapy (100% vs. 90.3%, p = 0.03), and the rate of stent vessel occlusion was lower (1.6% vs. 14.5%, p = 0.02). Both groups had comparable restenosis rates (26.5% vs. 26.9%, p = 0.87).

CONCLUSIONS

This study demonstrates that combined antiplatelet therapy after stent placement in patients with acute myocardial infarction is associated with an overall better clinical and angiographic outcome than anticoagulant therapy.

A randomized comparison of antiplatelet and anticoagulant therapy after the placement of coronary-artery stents

BACKGROUND

The clinical benefit of coronary-artery stenting performed in conjunction with coronary angioplasty is limited by the risk of thrombotic occlusion of the stent as well as hemorrhagic and vascular complications of intensive anticoagulation. We compared antiplatelet therapy with conventional anticoagulant therapy with respect to clinical outcomes 30 days after coronary-artery stenting.

METHODS

After successful placement of Palmaz-Schatz coronary-artery stents, 257 patients were randomly assigned to receive antiplatelet therapy (ticlopidine plus aspirin) and 260 to receive anticoagulant therapy (intravenous heparin, phenprocoumon, and aspirin). The primary cardiac end point was a composite measure reflecting death from cardiac causes or the occurrence of myocardial infarction, aortocoronary bypass surgery, or repeat angioplasty. The primary noncardiac end point comprised death from noncardiac causes, cerebrovascular accident, severe hemorrhage, and peripheral vascular events.

RESULTS

Of the patients assigned to antiplatelet therapy, 1.6 percent reached a primary cardiac end point, as did 6.2 percent of those assigned to anticoagulant therapy (relative risk, 0.25; 95 percent confidence interval, 0.06 to 0.77). With antiplatelet therapy, there was an 82 percent lower risk of myocardial infarction than in the anticoagulant-therapy group, and a 78 percent lower need for repeat interventions. Occlusion of the stented vessel occurred in 0.8 percent of the antiplatelet-therapy group and in 5.4 percent of the anticoagulant-therapy group (relative risk, 0.14; 95 percent confidence interval, 0.02 to 0.62). A primary noncardiac end point was reached by 1.2 percent of the antiplatelet-therapy group and 12.3 percent of the anticoagulant-therapy group (relative risk, 0.09; 95 percent confidence interval, 0.02 to 0.31). Hemorrhagic complications occurred only in the anticoagulant-therapy group (in 6.5 percent). An 87 percent reduction in the risk of peripheral vascular events was observed with antiplatelet therapy.

CONCLUSIONS

As compared with conventional anticoagulant therapy, combined antiplatelet therapy after the placement of coronary-artery stents reduces the incidence of both cardiac events and hemorrhagic and vascular complications.

Four-year experience with Palmaz-Schatz stenting in coronary angioplasty complicated by dissection with threatened or present vessel closure

BACKGROUND

Abrupt vessel closure after percutaneous transluminal coronary angioplasty (PTCA) is associated with major adverse events. Different surgical and nonsurgical approaches have been advocated to treat or prevent this complication. This study summarizes our 4-year experience with Palmaz-Schatz stenting for the management of 339 patients with present or threatened occlusion after PTCA.

METHODS AND RESULTS

Stent implantation was attempted in a total of 339 and 4959 patients with PTCA during the study period and was successful in 327 (96.5%). During the follow-up, events like death, myocardial infarction, need for revascularization (bypass surgery and repeat in-stent angioplasty), and major vascular complications were recorded. Angiographic follow-up at 6 months was performed in 89.3% of the eligible patients. As part of an initial policy, stenting was intended as a bridge to nonemergency bypass surgery in 26 patients. In 301 patients for whom stenting was intended as permanent treatment, early clinical course (first 4 weeks) was characterized by a 1.3% cardiac mortality and a 4.0% nonfatal myocardial infarction rate; bypass surgery was necessary in 1%, and 6.3% required early repeat PTCA. Surgical repair for peripheral vascular complications was required in 5.6%, and major bleeding events were encountered in 9%. The incidence of subacute stent closure was 6.9%, with subsequent recanalization successful in 86%; subacute stent closure was predicted by presence of vessel occlusion before stenting and localization of the stent in a vessel other than the right coronary artery. Survival rate at 2 years was 95.4%, survival without myocardial infarction was 91.1%, and event-free survival was 70.7%. Survival at 2 years was lower for patients with stents in bypass vein grafts and with myocardial infarction after stenting. Six-month control angiography revealed a restenosis rate of 29.6%.

CONCLUSIONS

Patients with present or threatened occlusion after PTCA may benefit from Palmaz-Schatz stenting. It is associated with a low mortality and myocardial infarction rate and with a long-term event-free rate comparable to that of uncomplicated PTCA.

Digital angiographic assessment of the physiological changes to the regional microcirculation induced by successful coronary angioplasty

BACKGROUND

Impulse response analysis of digital coronary angiographic images calculates a parameter known as the mean transit time of the microcirculation (Tmicro). This has been shown to accurately assess the regional microcirculatory response to proximal stenosis in relation to flow. Our goal was to apply impulse response analysis to patients undergoing successful angioplasty and to quantify the induced physiological changes with respect to quantitative angiographic measurements of stenosis dimensions.

METHODS AND RESULTS

We studied 24 patients before and after successful single-vessel percutaneous transluminal coronary angioplasty (PTCA). Minimal luminal stenosis area was increased from 0.9 +/- 0.6 before PTCA to 4.1 +/- 1.3 mm2 after PTCA (P < .0001). In all patients this was accompanied by an increase in the inverse of Tmicro (Tmicro-1), from 8.5 +/- 3.0 to 26.5 +/- 9.0 min-1 (P < .0001) with a linear correlation between Tmicro-1 and minimal luminal stenosis area (r = .73; SEE = 7.74). Stenosis flow reserve, estimated by integration of stenosis dimensions, increased in all patients from 1.8 +/- 1.0 to 4.5 +/- 0.4 after PTCA (P < .01). A comparison of Tmicro-1 with stenosis flow reserve revealed a nonlinear relation. In 16 patients undergoing PTCA of the left anterior descending or circumflex artery, contrast injections into the left main stem allowed simultaneous measurements of Tmicro-1 in the adjacent, nonstenotic artery. Adjacent artery Tmicro-1 did not change after PTCA (25.8 +/- 6.2 compared with 25.6 +/- 6.8 min-1 before PTCA; P = NS); moreover, Tmicro-1 of the dilated artery measured after PTCA was equivalent to the nonstenotic adjacent artery, indicating normalization of microcirculatory responses.

CONCLUSIONS

These data suggest that Tmicro-1 determined by digital angiographic impulse response analysis of a single contrast injection under resting flow conditions may be a practical method to assess the regional microcirculatory response to changes in stenosis severity effected by coronary angioplasty.

Digital angiographic impulse response analysis of regional myocardial perfusion. Detection of autoregulatory changes in nonstenotic coronary arteries induced by collateral flow to adjacent stenotic arteries

BACKGROUND

Our study compares the effect of acute proximal stenosis of a coronary artery supplying a myocardial perfusion bed with that of stenosis of an adjacent artery resulting in collateral flow diversion supplied by the same perfusion bed. These alterations in coronary physiology were quantified by digital angiographic impulse response analysis of contrast material mean transit time for the coronary microcirculation, Tmicro, and by flowmeter and microsphere assessment of flow and regional flow distribution.

METHODS AND RESULTS

In 25 open-chest, anesthetized dogs, progressive circumflex artery stenosis led to a concordant decrease of circumflex artery resting and hyperemic flow, coronary flow reserve, and inverse angiographic mean transit time Tmicro-1 (P < .01). Progressive left anterior descending artery stenosis led to no or only minor changes of circumflex artery resting or hyperemic flow or flow reserve; only occlusion induced a significant decrease of coronary flow reserve (from 4.0 +/- 0.7 to 3.2 +/- 0.5, P < .05), whereas resting flow was increased by +8.6 +/- 5.9%. In contrast, circumflex artery Tmicro-1 diminished significantly with critical left anterior descending artery stenosis and occlusion (from 16.7 +/- 4.2 to 12.6 +/- 2.2 [P < .05] and 12.0 +/- 3.0 min-1 [P < .01], respectively). In 8 dogs, collateral flow induced by left anterior descending artery occlusion was quantified by microsphere injections. The decrease of circumflex artery Tmicro-1 correlated with the magnitude of collateral flow (r = .76) and was associated with the angiographic extent of collateral filling.

CONCLUSIONS

Digital angiographic impulse response analysis is a sensitive method to detect the influence of proximal artery stenosis on an artery's myocardial perfusion bed as well as the changes induced by an adjacent artery stenosis inducing collateral flow diversion from the supplying myocardial perfusion zone.

Grading the angiographic extent of collateral filling. Comparison with coronary flow, collateral flow, and regional coronary flow distribution measurements

Angiography frequently demonstrates a collateral circulation in severe coronary artery disease. An easily applicable method to quantify collateral flow might be a useful adjunct for the assessment of the hemodynamic effects of coronary artery disease. The purpose of this study was to validate a visual scaling of the extent of angiographic collateral filling by comparison with flowmeter- and microsphere-derived measurements of collateral flow. In 12 open-chest dogs, collaterals from the circumflex artery were angiographically visualized (n = 80) by creating acute critical left anterior descending artery occlusion. The extent of collateral filling was graded in four levels from 0 = no visible filling to 3 = complete epicardial filling. Collateral filling correlated with the change in flow of the collateral supplying circumflex artery (delta Q; r = 0.84) which was + 5.3 +/- 4.6% with grade 1, + 9.1 +/- 3.5% with grade 2 and + 14.6 +/- 4.7% with grade 3 (p < 0.01). In parallel, coronary flow reserve decreased from 4.1 +/- 0.8 with grade 0 to 2.9 +/- 0.2 with grade 3 (p < 0.01). Colored microspheres were injected subselectively into the circumflex artery of 9 dogs (45 injections). The ratio of microspheres counted in the collateralized myocardium of the left anterior descending artery to the total number injected increased from 0.6 +/- 0.9% for grade 0 to 17.1 +/- 2.8% with grade 3 (p < 0.01). Absolute collateral flow derived from the microsphere counts averaged 5.5 +/- 0.9 ml/min with grade 3 and closely correlated with collateral filling grade (r = 0.88). Semiquantitative grading of angiographic collateral filling in response to acute coronary occlusion in a canine model correlates with an increase in collateral source artery flow, absolute collateral flow and a decrease in source artery flow reserve. These data suggest that this scale might be a simple but useful adjunct tool to assess the hemodynamic significance of a collateral circulation.

Positive ventilation-perfusion lung scan and positive Tl-201 myocardial scintigraphy due to Takayasu's arteritis

A case of Takayasu's arteritis is reported. Ventilation-perfusion lung scans and exercise thallium scintigraphy clearly showed pulmonary and coronary arterial involvement, respectively. Clinical examination and angiography revealed no other abnormal vascular findings. This case points out the difficulty in attempting to diagnose Takayasu's disease if only atypical vascular involvement is present.

Digital angiographic impulse response analysis of regional myocardial perfusion. Estimation of coronary flow, flow reserve, and distribution volume by compartmental transit time measurement in a canine model

A system impulse response function that describes the kinetics of radiographic contrast material transit through the coronary circulation was calculated from 175 selective digital angiograms of normal and stenotic arteries in 10 dogs during rest and hyperemia. The goal of the study was to determine if the flow and distribution volume characteristics of the epicardial coronary arteries and the myocardial microcirculation could be stimulated by specific mathematical compartments of a lagged normal density model impulse response function in which the flow/distribution volume ratio is the inverse of the mean transit time. The arterial compartment mean transit time correlated with flow (r = 0.75); however, the correlation was significantly improved in individual dogs (r = 0.83 +/- 0.13; p less than 0.005) and was highly dependent on the length of the conduit vessel. The microcirculation compartment mean transit time was distributed as two populations with respect to flow. There was a linear correlation during hyperemia (r = 0.87) and a nonlinear relation during rest, which was characteristic of an autoregulating system. Resting values of microcirculation compartment mean transit time correlated with coronary flow reserve (r = 0.84) and differed significantly between vessels that were normal and those with subcritical stenosis, critical stenosis, or total occlusion (p less than 0.01 for all comparisons). The estimated microcirculation compartment distribution volume increased from a minimum of 4.0 +/- 1.5 ml/100 g myocardium in normal vessels with resting flow to 11.2 +/- 3.5 ml/100 g during hyperemia. These data suggest that the model compartments functionally describe the physiological behavior of their anatomic analogues and permit the quantification of microcirculatory autoregulation from a single measurement at rest without provoking hyperemia.