Appropriate uses of angiographic follow-up in the evaluation of new technologies for coronary intervention

Folate therapy and in-stent restenosis after coronary stenting

BACKGROUND

Vitamin therapy to lower homocysteine levels has recently been recommended for the prevention of restenosis after coronary angioplasty. We tested the effect of a combination of folic acid, vitamin B6, and vitamin B12 (referred to as folate therapy) on the risk of angiographic restenosis after coronary-stent placement in a double-blind, multicenter trial.

METHODS

A total of 636 patients who had undergone successful coronary stenting were randomly assigned to receive 1 mg of folic acid, 5 mg of vitamin B6, and 1 mg of vitamin B12 intravenously, followed by daily oral doses of 1.2 mg of folic acid, 48 mg of vitamin B6, and 60 microg of vitamin B12 for six months, or to receive placebo. The angiographic end points (minimal luminal diameter, late loss, and restenosis rate) were assessed at six months by means of quantitative coronary angiography.

RESULTS

At follow-up, the mean (+/-SD) minimal luminal diameter was significantly smaller in the folate group than in the placebo group (1.59+/-0.62 mm vs. 1.74+/-0.64 mm, P=0.008), and the extent of late luminal loss was greater (0.90+/-0.55 mm vs. 0.76+/-0.58 mm, P=0.004). The restenosis rate was higher in the folate group than in the placebo group (34.5 percent vs. 26.5 percent, P=0.05), and a higher percentage of patients in the folate group required repeated target-vessel revascularization (15.8 percent vs. 10.6 percent, P=0.05). Folate therapy had adverse effects on the risk of restenosis in all subgroups except for women, patients with diabetes, and patients with markedly elevated homocysteine levels (15 micromol per liter or more) at baseline.

CONCLUSIONS

Contrary to previous findings, the administration of folate, vitamin B6, and vitamin B12 after coronary stenting may increase the risk of in-stent restenosis and the need for target-vessel revascularization.

Restenosis detected by routine angiographic follow-up and late mortality after coronary stent placement

BACKGROUND

Routine 6-month follow-up angiography (FU angio) is the most sensitive tool to detect restenosis. Thus, FU angio protocols have been a pivotal part of trials on long-term efficacy of stents. However, it is unclear if such protocols supply data relevant for the prognosis of individual patients. The purpose of this study was to assess the impact of angiographic restenosis detected by FU angio on late mortality after coronary stent placement.

METHODS AND RESULTS

We analyzed 2272 consecutive patients with successful stent placement performed from May 1992 through December 1996. All patients were scheduled for 6-month FU angio and contacted again after 4 years. FU angio was performed in 1958 patients. Of those, 557 patients (28.4%) had restenosis. After 4 years, 8.8% of patients with restenosis died, compared to 6.0% without (P =.02). There were several significant differences in clinical and angiographic characteristics between the 2 groups. In a multivariate analysis including those characteristics plus restenosis, only older age and restenosis were independent risk factors for late mortality. In patients with severe restenosis (>75% of lumen diameter; n = 231), late mortality was 7.6% in those with target vascular revascularization, compared to 14.9% without (P = not significant).

CONCLUSIONS

In this analysis, mortality 4 years after stent placement was higher in patients with angiographic restenosis. Restenosis was an independent risk factor for late mortality, with a potential benefit after target vessel revascularization in severe restenoses. These data suggest that routine FU angio after stenting provides data relevant for long-term prognosis of patients.

Predictors of clinical outcome following NIR stent implantation for coronary artery disease: analysis of the results of the First International New Intravascular Rigid-Flex Endovascular Stent Study (FINESS trial)

BACKGROUND

Patient and procedural characteristics associated with major adverse cardiac events following balloon angioplasty have been identified. Factors predictive of angiographic restenosis following coronary stent implantation have been reported, although patient variables associated with adverse clinical outcome are not well defined. HYPOTHESIS AND METHODS: To identify predictors of adverse clinical outcome following NIR stent implantation, clinical and angiographic characteristics of patients enrolled in the FINESS Trial were subjected to stepwise logistic regression analysis. From December 1995 through March 1996, NIR stent implantation was attempted in 255 patients (341 lesions) enrolled prospectively in a multicenter registry with broad entry criteria.

RESULTS

On stepwise logistic regression analysis, the presence of multivessel disease, diabetes, and the total length of the stented segment were predictive of major adverse cardiac events during 6-month follow-up. For every 1 mm increase in stent length, the risk for the combined end point of death or myocardial infarction increased by 3%. Lesion length was not predictive of clinical events on multivariate analysis.

CONCLUSIONS

Our data raise the possibility that an attempt to use shorter stents to cover significant stenoses, but not adjacent areas of visible narrowing, may improve outcome.

First international new intravascular rigid-flex endovascular stent study (FINESS): clinical and angiographic results after elective and urgent stent implantation. The FINESS Trial Investigators

OBJECTIVES

The purpose of this study was to determine the feasibility, safety and efficacy of elective and urgent deployment of the new intravascular rigid-flex (NIR) stent in patients with coronary artery disease.

BACKGROUND

Stent implantation has been shown to be effective in the treatment of focal, new coronary stenoses and in restoring coronary flow after coronary dissection and abrupt vessel closure. However, currently available stents either lack flexibility, hindering navigation through tortuous arteries, or lack axial strength, resulting in suboptimal scaffolding of the vessel. The unique transforming multicellular design of the NIR stent appears to provide both longitudinal flexibility and radial strength.

METHODS

NIR stent implantation was attempted in 255 patients (341 lesions) enrolled prospectively in a multicenter international registry from December 1995 through March 1996. Nine-, 16- and 32-mm long NIR stents were manually crimped onto coronary balloons and deployed in native coronary (94%) and saphenous vein graft (6%) lesions. Seventy-four percent of patients underwent elective stenting for primary or restenotic lesions, 21% for a suboptimal angioplasty result and 5% for threatened or abrupt vessel closure. Fifty-two percent of patients presented with unstable angina, 48% had a previous myocardial infarction, and 45% had multivessel disease. Coronary lesions were frequently complex, occurring in relatively small arteries (mean [+/-SD] reference diameter 2.8 +/- 0.6 mm). Patients were followed up for 6 months for the occurrence of major adverse cardiovascular events.

RESULTS

Stent deployment was accomplished in 98% of lesions. Mean minimal lumen diameter increased by 1.51 +/- 0.51 mm (from 1.09 +/- 0.43 mm before to 2.60 +/- 0.50 mm after the procedure). Mean percent diameter stenosis decreased from 61 +/- 13% before to 17 +/- 7% after intervention. A successful interventional procedure with < 50% diameter stenosis of all treatment site lesions and no major adverse cardiac events within 30 days occurred in 95% of patients. Event-free survival at 6 months was 82%. Ninety-four percent of surviving patients were either asymptomatic or had mild stable angina at 6 month follow-up.

CONCLUSIONS

Despite unfavorable clinical and angiographic characteristics of the majority of patients enrolled, the acute angiographic results and early clinical outcome after NIR stent deployment were very promising. A prospective, randomized trial comparing the NIR stent with other currently available stents appears warranted.

Clinical and angiographic comparison of matched patients with successful directional coronary atherectomy or stent implantation for primary coronary artery lesions

OBJECTIVES

This study was designed to compare the long-term clinical and angiographic effects of successful directional atherectomy and stent implantation and to examine whether restenosis is related to the mechanism of lumen improvement as well as the extent of lumen gain.

BACKGROUND

Directional atherectomy and coronary stent implantation have been shown to achieve a more optimal immediate result that may lead to a more favorable long-term angiographic outcome and fewer target vessel revascularizations than does angioplasty. However, it remains to be determined whether one of the devices used in these interventions provides consistently better results than the other.

METHODS

To allow meaningful comparisons a prospectively collected series of 117 patients successfully treated with atherectomy were individually matched with a prospectively collected series of 117 patients successfully treated with stent implantation. Matching for baseline characteristics identified patients with identical lesion location and lesion severity, and immediate and late angiographic and clinical outcome were compared. To evaluate the possibility of a procedure effect on restenosis, patients were further matched for both immediate angiographic outcome and baseline characteristics, providing 150 matched patients for comparison. As confirmatory analysis, multivariate models were constructed to predict late lumen diameter.

RESULTS

Matching resulted in two comparable groups with equivalent baseline clinical and stenosis characteristics (n = 117 pairs). Atherectomy led to a smaller immediate gain than stenting and, because late loss was similar in both groups, stenting resulted in a larger late lumen (1.96 +/- 0.51 vs. 1.66 +/- 0.55 mm, p < 0.0001). When patients were matched for immediate gain and baseline characteristics (n = 75 pairs), lumen loss was more pronounced after atherectomy, and thus the minimal lumen diameter at follow-up differed significantly between the two groups (1.66 +/- 0.53 vs. 1.90 +/- 0.47 mm, p = 0.004). This beneficial angiographic effect of stenting was accompanied by a reduced need for repeat interventions. Multivariate analysis confirmed the independent effect of the interventional device used, whereby less loss and greater lumen diameter at follow-up were predicted for stent implantation than for atherectomy.

CONCLUSIONS

Successful stent implantation provided a more favorable long-term angiographic outcome and lower rates of restenosis and need for target lesion revascularization than did atherectomy. This favorable effect of stenting not only is related to a larger, immediate gain, but also seems to attenuate late lumen loss.

Comparison of angioscopy, intravascular ultrasound imaging and quantitative coronary angiography in predicting clinical outcome after coronary intervention in high risk patients

OBJECTIVES

The purpose of this study was to identify qualitative or quantitative variables present on angioscopy, intravascular ultrasound imaging or quantitative coronary arteriography that were associated with adverse clinical outcome after coronary intervention in high risk patients.

BACKGROUND

Patients with acute coronary syndromes and complex lesion morphology on angiography are at increased risk for acute complications after coronary angioplasty. Newer devices that primarily remove atheroma have not improved outcome over that of balloon angioplasty. Intravascular imaging can accurately identify intraluminal and intramural histopathologic features not adequately visualized during coronary arteriography and may provide mechanistic insight into the pathogenesis of abrupt closure and restenosis.

METHODS

Sixty high risk patients with unstable coronary syndromes and complex lesions on angiography underwent angioscopy (n = 40) and intravascular ultrasound imaging (n = 46) during interventional procedures. In 26 patients, both angioscopy and intravascular ultrasound were performed in the same lesion. All patients underwent off-line quantitative coronary arteriography. Coronary interventions included balloon (n = 21) and excimer laser (n = 4) angioplasty, directional (n = 19) and rotational (n = 6) atherectomy and stent implantation (n = 11). Patients were followed up for 1 year for objective evidence for recurrent ischemia.

RESULTS

Patients whose clinical presentation included rest angina or acute myocardial infarction or who received thrombolytic therapy within 24 h of procedure were significantly more likely to experience recurrent ischemia after intervention. Plaque rupture or thrombus on preprocedure angioscopy or angioscopic thrombus after intervention were also significantly associated with adverse outcome. Qualitative or quantitative variables on angiography, intravascular ultrasound or off-line quantitative arteriography were not associated with recurrent ischemia on univariate analysis. Multivariate predictors of recurrent ischemia were plaque rupture on preprocedure angioscopy (p < 0.05, odds ratio [OR] 10.15) and angioscopic thrombus after intervention (p < 0.05, OR 7.26).

CONCLUSIONS

Angioscopic plaque rupture and thrombus were independently associated with adverse outcome in patients with complex lesions after interventional procedures. These features were not identified by either angiography or intravascular ultrasound.