Restenosis after directional coronary atherectomy. Effects of luminal diameter and deep wall excision

Plaque Tissue Components Obtained from De Novo Lesions may Predict Restenosis after Directional Coronary Atherectomy

BACKGROUND

A part of coronary stenotic lesions treated with directional coronary atherectomy (DCA) occur restenosis several months later. Specimens obtained by first DCA, present the histology of culplit lesions and may predict restenosis after PCI.

METHODS

The study group comprised 76 patients (male/female 65/11, age 61 ± 11 years). Restenosis, defined as > 50% stenosis diameter by quantitative cineangiography, was present in 26 patients. The other 50 patients (< 50% stenosis) constitute the "no restenosis" group. Inflammatory cells and other atheroma components were planimetrically quantified as a percentage of total tissue area.

RESULTS

As regards lymphocytes, neutrophils and smooth muscle cells, the grade of amount of cells did not differ between restenosis group and no restenosis group. The amount of obtained arterial media was similar, too. However, the area occupied by macrophages or calcified fragments was significantly larger in restenosis group than no restenosis group. And there was a tendency toward larger area occupied by cholesterol gruel, thrombus and myxomatous extracellular matrix (ECM) in restenosis group.

CONCLUSION

Rich macrophages infiltration, calcified fragments, cholesterol rich gruel and myxomatous ECM from primary lesions can be predictors of restenosis after DCA, suggesting a possible role in restenotic process after PCI.

Predictors of vessel remodeling following directional coronary atherectomy

The purpose of this study was to clarify predictors of vessel remodeling following directional coronary atherectomy (DCA). Negative remodeling after DCA leads to restenosis. However, little is known about the predictors of the vessel remodeling. Serial IVUS was performed in 43 lesions. The vessel remodeling was defined as adaptive if vessel area at follow-up minus postprocedure vessel area was > 0 mm2, or as constrictive if < 0 mm2. Adaptive remodeling occurred in 21 (49%) lesions. Postprocedure percent plaque area was smaller in the adaptive group (32.9% +/- 5.7% vs. 45.5% +/- 8.8%; P < 0.005). At follow-up, vessel area was larger in the adaptive group. However, plaque area was similar between the two groups. As a result, lumen area was larger in the adaptive group. Multivariate analyses showed that postprocedure percent plaque area < 40% was the only predictor of adaptive remodeling (odds ratio, 6.68; P < 0.05).

A novel measurement technique to assess the effects of coronary brachytherapy in clinical trials

This paper presents a novel measurement technique to assess the effects of coronary brachytherapy. This new technique is based upon the conventional quantitative coronary analysis (QCA) technique, which is accepted worldwide as an accurate and reliable analysis tool for clinical trials. This paper provides the definitions and main issues important for correct brachytherapy analysis. Based on these definitions, this novel technique is implemented as an extension of conventional QCA software, as a multisegmental analysis tool. It allows to follow the influence of radiation on restenosis, and the mutual relation between intervention devices. A pilot interobserver study was performed to assess the reliability and reproducibility of the brachytherapy analysis tool, using 15 patient cases. The validation results show that the segment lengths, minimum lumen diameter, and reference diameters of the user-defined and derived (sub)segments can be assessed reproducible. However, these good results can only be obtained, when strict and extensive image acquisition and image analysis protocols are followed. From this pilot validation study presented in this paper and only based on a small number of patients, we may conclude that the software can be applied to clinical trials.

Directional coronary atherectomy: the Vienna experience

BACKGROUND

Several multicenter trials have shown excellent results for directional coronary atherectomy (DCA) in a selected patient cohort. To prove the applicability of this method in daily clinical routine and a nonselected patient cohort, we analyzed 46 consecutive cases performed at our catheterization lab.

METHODS

DCA was performed as a routine procedure in 45 suitable patients. Balloon dilatation or stent implantation postprocedure was accomplished only in case of unsatisfactory results. Quantitative coronary angiography was achieved pre- and postprocedure as well as at 6-month follow-up.

RESULTS

Optimal atherectomy < 20% residual stenosis was reached in 24 (52%) of 46 target lesions and a residual stenosis < 50% in 46 (100%) lesions. Procedure-related complications occurred in three (6%) patients (one major complication, death, < 24 hours, 2%; two minor complications, pseudoaneurysm, 4%). The 6-month angiographic follow-up revealed a binary restenosis rate of 29% (n = 11). Ten out of 11 restenotic lesions required revascularization. When patients were stratified in two groups according to their preprocedural minimal lumen diameter (MLD), this parameter proved to be a very strong predictor of outcome. The percentage of restenosis was significantly higher in patients with an MLD > 1.60 mm compared to patients with a smaller MLD (54% vs 19.3%; P < 0.0001). Reference vessel diameter preprocedure did not differ significantly.

CONCLUSIONS

Our study demonstrated that DCA is a suitable technique for the daily clinical routine, as the rates of complications and restenosis were similar to that in a highly selective patient cohort. Additionally, our study showed that patient selection should include preprocedural analysis of MLD in order to achieve optimal results. Therefore, atherectomy yielded comparable results to other conventional techniques and may be used instead of or in combination with them.

Coronary artery restenosis after atherectomy is primarily due to negative remodeling

The primary cause of restenosis following directional coronary atherectomy (DCA) remains obscure. "Negative remodeling," a decrease in vessel area, is believed to be more causative than is increase in plaque area. The DCA technique used in these patients, designed to facilitate the removal of plaque, should allow a more precise evaluation of the relative roles of these two mechanisms. Twenty-five patients underwent DCA. In 17, complete angiographic and intravascular ultrasound (IVUS) images were obtained before and after DCA and at follow-up (6 to 9 months). Internal elastic lamina (IEL), lumen, and plaque areas were calculated at preatherectomy, postatherectomy, and follow-up. Postatherectomy, the mean IEL area increased by 32% and the mean plaque area decreased by 51%, resulting in a significant mean increase in lumen area, 500%. At follow-up when compared to postatherectomy, the change in IEL area was variable; however, the mean did not change significantly (p = 0.58). Plaque area change, when standardized for initial vessel size, was small (mean increase 2.8 +/- 3.5%). The mean lumen area did not decrease significantly at follow-up (p = 0.43). A highly significant correlation (r = 0.96) was noted between IEL area change and lumen area at follow-up. In contrast, the correlation between plaque area change and lumen area change over the same period was much less significant (r = 0.64). These data indicate that decrease in IEL area primarily is responsible for restenosis.

Comparison of quantitative coronary angiographic results after directional coronary atherectomy and balloon angioplasty of protected left main coronary stenosis

We compared the angiographic and clinical outcomes after directional coronary atherectomy (DCA, 13 patients) with those after conventional balloon angioplasty (BA, 21 patients) in patients with protected left main coronary artery stenosis. The initial success rate was 100% in the DCA group and 81% (17 of 21) in the BA group. Restenosis was present in 2 of 11 patients in the DCA group and 9 of 16 patients in the BA group (18% vs. 56%, P < 0.05). DCA and BA improved a minimal lumen diameter. The initial gain after DCA was greater than that after BA. At follow-up, the minimal lumen diameter was larger and the percentage diameter stenosis was smaller in the DCA group than in the BA group. The late loss and loss index were equivalent in both groups. Compared with conventional BA, DCA in protected left main coronary artery stenosis is associated with a higher angiographic success rate and provides a wider luminal diameter with reduced incidence of restenosis.

Arterial remodeling after balloon angioplasty of the coronary artery: an intravascular ultrasound study. PICTURE Investigators. PostTreatment IntraCoronary Transluminal Ultrasound Result Evaluation

OBJECTIVE

Before balloon dilation, failure of compensatory enlargement and even arterial shrinkage are frequently observed at the lesion site in response to plaque accumulation. Balloon angioplasty may be regarded as artificial remodeling to enlarge the artery. The prevalence of the different types of arterial wall remodeling after applied stretch by balloon angioplasty is unknown.

METHODS AND RESULTS

In 181 patients an intravascular ultrasound study was performed after coronary balloon angioplasty (n = 200 lesions). The vessel area was measured at a proximal and distal reference site and at the lesion site. Subsequently, the relative vessel area [(Vessel area lesion site)/Vessel area reference site) x 100] was calculated. Lesions were classified in three groups on the basis of their relative vessel areas: > or =105%, <105% but >95%, and < or =95%. A relative vessel area > or =105%, indicating enlargement compared with the reference site, was observed in 84 (44%) lesions. A relative vessel area <105% but >95% was observed in 43 (22%) lesions. A relative vessel area < or =95%, indicating "shrinkage" compared with the reference site, was observed in 66 (34%) lesions.

CONCLUSIONS

After balloon angioplasty, the vessel area was found to be smaller compared with the reference site in 34% of the lesions. This small vessel area at the lesion site compared with a reference site may be a reflection of insufficient stretch by balloon angioplasty.

Effectiveness of tranilast on restenosis after directional coronary atherectomy

Tranilast is an antiallergic drug used widely in Japan that also inhibits the migration and proliferation of vascular smooth muscle cells. This pilot study was undertaken to determine the effectiveness of tranilast on restenosis after successful directional coronary atherectomy. After the procedure, 40 patients (56 lesions, tranilast group) were treated with oral tranilast for 3 months, and 152 patients (188 lesions, control group) did not receive tranilast. Angiographic and clinical variables were compared between the two groups. The minimal lumen diameter was significantly larger in the tranilast group than in the control group at both 3-month (2.08 vs 1.75 mm, p = 0.004) and 6-month follow-up (2.04 vs 1.70 mm, p = 0.003). The diameter stenosis in the tranilast group was smaller than that in the control group both 3 months (28% vs 40%, p = 0.0007) and 6 months (30% vs 43%, p = 0.0001) after the procedure, with a lower restenosis rate (percent diameter stenosis > or =50) in the tranilast group at 3 months (11 % vs 26%, p = 0.03). The number of clinical events over the 12-month period after the procedure was significantly reduced by tranilast administration (p = 0.013). These findings suggest that the oral administration of tranilast strongly prevents restenosis after directional coronary atherectomy.

Directional coronary atherectomy for the treatment of acute myocardial infarction

Directional coronary atherectomy (DCA) was performed after intracoronary thrombolysis in 32 patients with a first acute myocardial infarction. DCA was successful in 31 (97%) of 32 patients. Abrupt closure of the treated segment occurred in one patient but was managed successfully by conventional balloon angioplasty. Repeat angiography was performed in 32 patients before discharge (2.7 +/- 0.7 weeks later) and in 29 patients during the follow-up (4.5 +/- 1.5 months later). No restenosis (stenosis > 50%) occurred before discharge; however restenosis occurred in 12 (41%) of 29 patients during follow-up. The restenosis rate in patients with subintimal resection was significantly higher than in those with intimal resection (78% vs 25%, p < 0.01). These data suggest that DCA in patients with acute myocardial infarction is feasible for persistent early patency of the infarct-related coronary artery, but late restenosis continues to limit success and subintimal resection may increase the restenosis rate during the follow-up.

Impact of diabetes mellitus on percutaneous revascularization (CAVEAT-I). CAVEAT-I Investigators. Coronary Angioplasty Versus Excisional Atherectomy Trial

We examined the relation between diabetes mellitus and outcomes in patients undergoing percutaneous coronary revascularization in the Coronary Angioplasty Versus Excisional Atherectomy Trial (CAVEAT-I), a randomized trial comparing treatment with either percutaneous transluminal coronary angioplasty or directional atherectomy for de novo lesions in native coronary arteries. Acute success and complication rates, 6-month angiographic restenosis rates, and 1-year clinical outcomes were compared between diabetic and nondiabetic patients undergoing each procedure. Acute success rates between diabetic (n = 191) and nondiabetic (n = 821) patients were similar for both revascularization techniques. Except for the need for dialysis, complication rates were also similar. Six months after atherectomy, diabetic patients had significantly more angiographic restenosis than nondiabetics (59.7% vs 47.4%) and significantly smaller minimum luminal diameters (1.20 vs 1.40 mm). Diabetics undergoing atherectomy required more frequent bypass surgery (12.8% vs 8.5%) and more repeat percutaneous revascularizations (36.5% vs 28.1%) than nondiabetics undergoing atherectomy. Restenosis rates, minimum luminal diameters and repeat revascularizations between diabetics and nondiabetics undergoing angioplasty were similar. The higher restenosis and repeat revascularization rates and the smaller minimum luminal diameter at follow-up in diabetic patients suggest that atherectomy may provide only modest benefit for these patients. The increased restenosis rate in diabetics undergoing atherectomy (but not angioplasty) requires further evaluation.

Long-term clinical follow-up after directional coronary atherectomy

Although several studies have been done to assess the safety, efficacy, and angiographic restenosis rates of directional coronary atherectomy (DCA), there have been no studies to document the need for repeat revascularization of the target vessel based purely on recurrence of symptoms. To answer this question, clinical and angiographic data were obtained for 187 consecutive patients undergoing this procedure on a native coronary artery utilizing a lesion specific approach in a referral hospital. Most of the patients had anginal symptoms that were not well controlled with medical therapy. The decision to perform DCA was based on the lesion characteristics (i.e., eccentric, ulcerated, or irregular discrete lesions in a large epicardial vessel). The procedure was successful in 96% of patients. In-hospital major complications were seen in 6 patients (3%) including acute myocardial infarction in 3 (1.5%) and emergency coronary artery bypass surgery in the other 3 (1.5%). There were no deaths. Among 141 consecutive successful patients on whom the procedure was performed between January 1992 and June 1994, 128 (91%) were contacted. At 6 months, revascularization was required in 20 patients for recurrent anginal symptoms, and there were no deaths or myocardial infarctions. The clinical restenosis rate, therefore, was 15.6%. At long-term follow-up (25 +/- 9 months), revascularization was performed in 3 more patients. One patient had a myocardial infarction and 3 patients died of noncardiac causes. Among those without clinical restenosis, 83% patients were asymptomatic and the rest had infrequent chest pains effectively managed with medications. The patients in the study group were using an average of 1.2 cardiac medications. Quality of life improved in 74% of the patients. Thus, in this study utilizing a lesion specific approach, the success rate for DCA was comparable to the published trials and in-hospital complications were few. The long-term clinical outcome was favorable with a low rate of clinical restenosis requiring repeat revascularization.

Coronary artery and saphenous vein graft remodeling: a review of histologic findings after various interventional procedures--Part VI

Catheter balloon angioplasty is a well accepted form of nonsurgical treatment of acutely and chronically obstructed coronary artery vessels. It is also the centerpiece for various new intervention techniques. Their morphologic effects on the site of obstruction has been termed "remodeling." Part VI of this six-part series focuses on atherectomy and restenosis tissue obtained by atherectomy procedures.

Comparison of balloon angioplasty and Simpson atherectomy for lesions in the femoropopliteal artery: angiographic and clinical results of a prospective randomized trial

PURPOSE

This study involves a prospective randomized trial comparing clinical and angiographic results of balloon angioplasty (BA) and Simpson directional atherectomy (DA) in patients with short lesions in the femoropopliteal artery causing symptoms of intermittent claudication.

MATERIALS AND METHODS

Thirty-five patients were treated with BA and 38 with DA. Procedural complications were seen in eight patients. Residual stenoses immediately after the procedure with between 30% and 50% diameter reduction (DR) were observed in three patients after BA and in five patients after DA. In all other patients, residual stenosis was less than 30% DR. Two study end-points during a 2-year follow-up were used: the angiographic occurrence of restenosis with a DR of 50% or greater or the recurrence of symptoms.

RESULTS

Clinical success after 2 years, according to the criteria of the Society for Vascular Surgery/International Society for Cardiovascular Surgery, was seen in 79% of the BA patients and 56% of the DA patients (P = .07). The 2-year primary angiographic patency rates were 67% in patients treated with BA and 44% in patients treated with DA (P = .06). The secondary angiographically determined patency rates were 80% and 65%, respectively (P = .15).

CONCLUSION

Simpson atherectomy is an interventional technique to treat arterial lesions in the femoropopliteal artery with an acceptably low complication rate. The clinical and angiographic results of DA and BA are comparable. DA should not be used to replace BA for routine treatment of short femoropopliteal lesions.

Effect of coronary artery size on the prevalence of atherosclerosis

To investigate the effect of coronary artery size on the prevalence of atherosclerosis, we measured the diameters of the major coronary arteries prospectively in 884 consecutive patients referred for coronary arteriography. For each artery, we assigned patients to 3 groups: group S (small) and group L (large) with diameters >1SD smaller and larger, respectively, than the mean; and group A (average), with diameters within 1SD of the mean. As specified during study design, we compared the frequency of lesions > or = 50% diameter stenosis in groups S and L for each artery. We adjusted for relevant covariates by performing logistic regression on data from all 884 patients with coronary diameter entered as a continuous variable. In group S versus L, respectively, the frequency of > or = 50% lesion was 6.5% versus 2.4% (p = 0.13) in the left main artery; 61.3% versus 35.8% (p = 0.0001) in the right coronary artery; 58.1% versus 40.7% (p = 0.008) in the left anterior descending artery, and 47.4% versus 22.2% (p = 0.0001) in the circumflex artery. Multivariate analysis showed that coronary diameter was a significant independent predictor of lesions in the right coronary artery (p = 0.000001), left anterior descending artery (p = 0.001), and circumflex artery (p = 0.0002) and nearly significant in the left main artery (p = 0.077). Thus, small coronary artery size may be a risk factor for atherosclerosis.

Effect of subintimal resection on initial outcome and restenosis for native coronary lesions and saphenous vein graft disease treated by directional coronary atherectomy. A report from the CAVEAT I and II investigators. Coronary Angioplasty Versus Excisional Atherectomy Trial

OBJECTIVES

This study was designed to determine whether the depth of tissue resection affected either immediate outcome or subsequent restenosis in patients treated by directional coronary atherectomy (DCA) in the Coronary Angioplasty Versus Excisional Atherectomy Trial (CAVEAT) I and II studies.

BACKGROUND

The relation between the depth of tissue resection, immediate outcome and subsequent restenosis in lesions treated with DCA has been controversial.

METHODS

In CAVEAT I, 412 patients undergoing DCA had tissue samples available for analysis by the core laboratory, whereas in CAVEAT II, 113 patients had vein graft tissue specimens available.

RESULTS

Subintimal deep arterial wall resection was demonstrated in 169 patients (41%) in CAVEAT I and 40 (35%) in CAVEAT II. The depth of tissue resection did not affect initial procedural outcome in either CAVEAT I or CAVEAT II, nor did it affect subsequent restenosis rates at 6 months in native coronary lesions (CAVEAT I, 50.8% for intimal resection vs. 51.2% for subintimal resection). In patients treated with vein graft disease (CAVEAT II), restenosis rates varied; when resection was limited to the intima, a restenosis rate of 40.4% was documented, whereas in patients with subintimal resection, the restenosis rate was 57.1%. This difference was not statistically significant (p = 0.144).

CONCLUSIONS

This combined randomized series of DCA for treatment of primary native coronary artery and vein graft stenoses with quantitative coronary angiography and core laboratory pathologic assessment resolves the controversy created by previous experimental and clinical data regarding deep vessel wall resection and immediate and longer outcome. Directional atherectomy with deep arterial wall resection as practiced in these studies is safe and does not jeopardize initial success rates. More important, deep wall resection is not associated with significantly increased restenosis rates.

Coronary restenosis

Return of angina within 6 months of a catheter-based treatment of coronary artery disease usually reflects restenosis due to an overly aggressive local healing response to the procedure-related arterial injury. The restenotic lesion should be treated aggressively. Patients with preexisting diabetes mellitus, renal failure requiring hemodialysis, and left anterior descending artery lesions should be considered to be at exceedingly high risk for clinically significant restenosis. Exercise testing is indicated for all patients who experience a return of their angina within 6 months of an interventional procedure. Nurse practitioners in the primary care setting may be the first clinicians to hear of the return of angina. Patients should always be reassured that repeat intervention is almost always possible and is generally effective in providing long-term relief. New devices (in particular the Palmaz-Schatz stent) may help reduce the likelihood of restenosis, to the extent that they provide a large acute post-treatment lumen diameter that is more tolerant of intimal hyperplasia without producing significant narrowing. Until adjunctive drug therapy is found that effectively reduces the local tissue response to interventional therapy, all clinicians involved in caring for patients following such procedures will need to be vigilant and knowledgeable about recognizing and treating restenosis.

Mid-term and long-term results with directional atherectomy of vein graft stenoses

PURPOSE

The purpose of this study was to evaluate the outcomes of our 6-year experience with directional atherectomy used for treatment of stenoses in infrainguinal vein grafts.

METHODS

From March 1988 to April 1994, 52 directional atherectomy procedures were undertaken in 42 patients to treat 67 stenoses in 44 vein grafts. Follow-up consisted of periodic physical examinations and graft surveillance; ankle/brachial indexes, pulse volume recordings, and color-flow duplex ultrasonography. Follow-up angiography (n = 18) was performed for recurrent symptoms, reproducible drop in ankle/brachial index of greater than 0.15, a twofold to threefold focal increase in peak systolic velocity, or incidentally during evaluation of the opposite leg.

RESULTS

Forty-nine of 52 (94%) procedures were technically successful. In two the residual diameter stenosis was greater than 30%, and in one atherectomy could not be performed. Complications were minor in six (11%) and major in three (6%): two acute graft occlusions and one delayed pseudoaneurysm at the atherectomy site. There were no deaths at 30 days. With a mean follow-up of 21 +/- 18 months, 36 of 44 grafts (82%) remained patent without restenosis; 6 others were patent but considered "failed"--5 (11%) with restenosis, 1 with a pseudoaneurysm; and 2 grafts (5%) occluded. Clinically 33 of 44 extremities (75%) were asymptomatic during follow-up. Claudication improved in five, recurred in three, and was unchanged in one. There was one below-knee amputation. Life-table analysis including all 52 procedures reveals cumulative primary atherectomy patency rates for the 44 grafts of 82%, 78%, and 78%, respectively, at 1, 2, and 3 years after atherectomy, and 86%, 83%, and 83% for the 67 individual stenoses treated.

CONCLUSIONS

Directional atherectomy of vein graft stenoses has high technical and clinical success rates, acceptably low morbidity rates, and offers better sustained patency rates than balloon angioplasty. Its long-term patency rate seems to approach that of surgical vein patch angioplasty.

Unplanned use of intracoronary stents for the treatment of a suboptimal angiographic result after conventional balloon angioplasty

This observational single-center trial examines the safety and efficacy of unplanned endoluminal stenting for the treatment of a suboptimal angiographic result (defined as a residual stenosis after angioplasty of 40% to 50% without delayed runoff as estimated by visual assessment) after conventional coronary angioplasty in native, new-onset, coronary artery stenoses. Between October 1991 and April 1994, 101 patients with suboptimal results after coronary angioplasty in new-onset lesions were treated by endoluminal Wiktor (41 patients) and Palmaz-Schatz (60 patients) stent implantation. Stenting was a technical and angiographic success in all cases. In-hospital complications were subacute closure (2%) and vascular complications at puncture site necessitating surgery (12%) or blood transfusion (3%). No myocardial infarction occurred, nor was any urgent bypass surgery performed. At follow-up restenosis was detected in 16 (20%, 80% angiographic follow-up rate) patients requiring repeat angioplasty (8%) and elective bypass grafting (4%). Myocardial infarction was not documented. However, one patient died suddenly at 5 months of follow-up. The unplanned use of intracoronary stents is a safe and effective therapeutic option for the treatment of a suboptimal angiographic result after conventional angioplasty in new-onset lesions. This approach guarantees a high immediate angiographic success but implies a considerable incidence of vascular complications at puncture site.

Three-dimensional intravascular ultrasound assessment of plaque volume after successful atherectomy

The primary purpose of directional coronary atherectomy is the removal of intraluminal plaque. Angiography allows assessment of residual lumen narrowing but is limited in the assessment of residual plaque burden. Intravascular ultrasound has proven useful in assessing plaque size, but current use has been limited to a single, representative cross-sectional image rather than an evaluation of the entire plaque volume. To determine the volume of residual plaque after angiographically successful directional coronary atherectomy ( < or = 20% residual stenosis), we performed intravascular ultrasound in 19 patients before and after atherectomy. Only coronary lesions optimal for three-dimensional analysis (a single, discrete stenosis in a nontortuous, noncalcified native coronary artery) were selected. A 2.9F sheath-design intravascular ultrasound catheter with a motorized pullback device was used in all patients. The cross-sectional area of the artery (defined by the medial-adventitia border), the lumen, and the plaque were measured at 1 mm intervals over a 15 to 20 mm segment, which included the target lesion and a proximal reference segment (n = 362 cross-sections), before and after atherectomy. The volumes of the artery, vessel lumen, or plaque were calculated with a modified Simpson's equation and compared with standard area measurements at the point of maximal stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Strategy of diagnostic imaging before and after PTCA

It is now widely accepted that percutaneous transluminal coronary angioplasty (PTCA) is an effective nonsurgical technique for achieving coronary revascularization. Exercise electrocardiography remains the standard procedure for functional evaluation before, early, and late after angioplasty because of its availability, safety, and limited cost. The drawback of exercise testing is its low specificity and the fact that the attainment of diagnostically useful data requires a level of exercise that substantially increases myocardial oxygen demand. Exercise thallium imaging has been shown to be highly predictive of restenosis and adverse events after angioplasty, but it is possible that myocardial perfusion may not return to normal immediately after successful revascularization. Stress echocardiography has many practical advantages over scanning tests, as result of its lower cost, shorter imaging time, and the absence of radiation exposure. Dipyridamole echocardiography testing (DET) is an exercise-independent method of evaluating patients who have to undergo coronary angioplasty. Before PTCA, DET allows the clinician to localize the site and extent of myocardial ischemia anatomically. Early after a successful procedure, DET identifies a group at high risk for the late recurrence of symptoms. Late after PTCA, DET is more accurate than exercise electrocardiography in detecting restenosis or disease progression. In asymptomatic patients with exercise-induced ST depression, DET has the same good diagnostic accuracy as thallium scintigraphy. For these reasons, as well as because of its noninvasive nature and availability, DET should be considered an attractive option for the evaluation of patients after anatomically successful angioplasty.

Directional atherectomy versus balloon angioplasty for coronary ostial and nonostial left anterior descending coronary artery lesions: results from a randomized multicenter trial. The CAVEAT-I investigators. Coronary Angioplasty Versus Excisional Atherectomy Trial

OBJECTIVES

We hypothesized that atherectomy would be superior to balloon angioplasty for ostial and nonostial left anterior descending coronary artery lesions.

BACKGROUND

Balloon angioplasty of ostial coronary artery lesions has been associated with a lower procedural success rate and a higher rate of complications and of restenosis than angioplasty of nonostial stenoses. Directional coronary atherectomy has been proposed as an alternative therapy for ostial lesions.

METHODS

In the Coronary Angioplasty Versus Excisional Atherectomy Trial (CAVEAT-I), 1,012 patients were randomized to undergo either procedure; 563 patients had proximal left anterior descending coronary artery lesions, of which 74 were ostial. We compared balloon angioplasty with directional atherectomy for early and 6-month results for ostial as well as nonostial proximal left anterior descending coronary artery lesions.

RESULTS

Directional atherectomy led to an initially higher gain in minimal lumen diameter for ostial lesions (1.13 vs. 0.56 mm, respectively, p < 0.001) but a higher rate of adjudicated non-Q wave myocardial infarction (24% vs. 13%, respectively, p < 0.001) than balloon angioplasty and no improvement in restenosis rates (48% vs. 46%, respectively). In the nonostial proximal left anterior descending coronary artery lesions, angiographic restenosis was reduced (51% vs. 66%, p = 0.012), but this was also associated with a higher rate of periprocedural myocardial infarction (8% vs. 2%, p = 0.008 by site and 24% vs. 8%, p < 0.001 by adjudication) and no difference in the need for subsequent coronary artery bypass surgery (7.3% vs. 8.4%, respectively) or repeat percutaneous coronary intervention (24% vs. 26%, respectively).

CONCLUSIONS

For ostial left anterior descending coronary artery stenoses, both procedures yielded similar rates of initial success and restenosis, but atherectomy was associated with more non-Q wave myocardial infarction. In this trial the predominant angiographic benefit (increased early gain and less angiographic restenosis) of atherectomy for the left anterior descending coronary artery was in proximal nonostial lesions. However, the tradeoffs for this angiographic advantage were more in-hospital myocardial infarctions and no decrease in clinical restenosis.

High-resolution MR imaging of human arteries

The authors studied the magnetic resonance (MR) imaging appearance of excised human arteries and correlated these findings with those from histologic sections obtained in corresponding planes. Imaging was performed with a 1.5-T clinical imager modified with an additional gradient insert capable of a 30 mT/m gradient. High-resolution images of arteries obtained at autopsy indicated that the medial and adventitial layers could be distinguished and that T2-weighted sequences offered superior contrast. Intimal thickening could be detected at a relatively early stage as a long T2 rim on the luminal surface of the artery. Atherosclerotic plaque was found to have MR properties similar to those of intimal thickening, although necrotic regions within plaque had low signal intensity. Fat suppression sequences did not significantly alter the appearance of atherosclerotic plaque. Calcified plaque produced effects ranging from slight signal loss to signal void. MR imaging findings correlated reliably with the tissue types indicated by histologic analysis.

Optimal use of directional coronary atherectomy is required to ensure long-term angiographic benefit: a study with matched procedural outcome after atherectomy and angioplasty

OBJECTIVES

This study was designed to examine whether restenosis is related to the extent or mechanism of lumen improvement and to explore angiographic determinants of optimal atherectomy.

BACKGROUND

Directional atherectomy induces a greater extent of immediate gain and late loss but has not been found to yield a better late angiographic lumen than angioplasty in randomized trials. The difference in lumen renarrowing may be related to either the extent or the mechanism of immediate gain. The design of previous studies has precluded the detection of a device-specific effect on restenosis.

METHODS

A retrospective analysis was based on matching a prospectively collected series of 80 native coronary arteries successfully treated with atherectomy with a prospectively collected series of 80 native coronary arteries successfully treated with balloon angioplasty. Angiographic analysis was performed in 160 lesions to explore whether a specific device-related effect exists. Multivariate analyses were performed to determine the correlates of minimal lumen diameter at follow-up and late lumen loss and to identify the procedural characteristics for optimal atherectomy.

RESULTS

Matching resulted in two comparable groups with equivalent baseline clinical and stenosis characteristics. By study design, atherectomy and angioplasty resulted in similar mean (+/- SD) immediate lumen gain (1.15 +/- 0.44 vs. 1.10 +/- 0.40 mm, p = 0.50). However, lumen loss was more pronounced after atherectomy, and, thus, the minimal lumen diameter at follow-up differed significantly between the two groups (1.78 +/- 0.57 vs. 2.00 +/- 0.56 mm, p = 0.001). Device type was retained in the multivariate analysis as an independent predictor of late minimal lumen diameter and lumen loss. Multivariate analysis identified vessel size and immediate gain as determinants of optimal atherectomy.

CONCLUSIONS

Restenosis is a consequence not only of the extent of lumen improvement but also of the mechanism of vessel wall injury (debulking vs. dilating). While performing atherectomy, the operator should strive for an optimal procedural result to accommodate an increased intimal hyperplastic response.

Long-term histologic patency after percutaneous transluminal coronary angioplasty is predicted by the creation of a greater lumen area

OBJECTIVES

This study assessed the relation between histologic acute and long-term lumen size after coronary angioplasty.

BACKGROUND

Angiographic studies suggest that the creation of a larger acute lumen is associated with a reduced incidence of restenosis. Histologic evaluation of the influence of the acute lumen on late outcome has not been previously reported.

METHODS

Detailed histologic examination and planimetry were performed in 28 postmortem coronary arteries subjected to angioplasty at an average of 71 weeks antemortem. The lumen area on each histologic segment was defined as the final lumen area. The lumen area immediately after angioplasty, the acute lumen area, was defined by the sum of the neointimal area plus final lumen. A final lumen area > or = 25% of the arterial area was considered a long-term success; a final lumen area < 25% was considered a long-term failure.

RESULTS

Arterial size and neointimal area were similar in long-term successes and failures. In successes, the mean (+/- SD) acute lumen area was greater than in failures (4.1 +/- 1.9 vs. 2.7 +/- 1.4 mm2, respectively, p < 0.001). The acute lumen area as a percent of arterial area was 46 +/- 10% in successes versus 27 +/- 11% in failures (p < 0.0001). The corresponding estimated mean acute lumen diameter stenosis was 24 +/- 8% in successes versus 42 +/- 12% in failures (p < 0.0001). Plaque area was greater in failures (7.1 +/- 3.2 mm2) than in successes (4.8 +/- 2.4 mm2, p < 0.002).

CONCLUSIONS

Neointimal proliferation after angioplasty occurs in all dilated coronary arteries, and the amount of neointimal growth is independent of vessel size. The creation of a larger lumen and a larger lumen as a percent of vessel size were associated with an improved long-term histologic patency.

Randomized trials of directional coronary atherectomy: implications for clinical practice and future investigation

OBJECTIVES

This study compared and contrasted the randomized trials of directional atherectomy and coronary angioplasty for de novo native coronary artery lesions.

BACKGROUND

The results of two randomized trials, the Coronary Angioplasty Versus Excisional Atherectomy Trial (CAVEAT) and the Canadian Coronary Atherectomy Trial (CCAT), comparing initial and intermediate-term outcome of directional coronary atherectomy and conventional coronary angioplasty in de novo native vessels, have been reported. In CAVEAT any coronary artery segment that could be treated by either technique was included; in CCAT only nonostial proximal left anterior descending coronary artery stenoses were studied.

METHODS

The primary end point was 6-month angiographic restenosis. Clinical outcome end points at 6 months included death, myocardial infarction, emergency bypass surgery and abrupt closure.

RESULTS

Initial angiographic success rates were significantly improved with directional coronary atherectomy compared with conventional angioplasty (89% vs. 80% for CAVEAT; 98% vs. 91% for CCAT). Also, the initial improvement in minimal lumen diameter and final immediate postprocedural residual diameter stenosis were better with atherectomy. In CCAT, there was no difference in initial complications; in CAVEAT, non-Q wave myocardial infarction rates and abrupt closure were increased with atherectomy. Despite improved success rates and better lumen achieved with atherectomy, in CCAT there was no difference in angiographic restenosis (46% for directional atherectomy vs. 43% for angioplasty). In CAVEAT, in a prespecified subset analysis involving the proximal left anterior descending coronary artery, restenosis was both significantly and clinically less for directional atherectomy (51% vs. 63%). For non-left anterior descending coronary artery segments, there was no difference.

CONCLUSIONS

These studies document the difference between achievement of an excellent initial angiographic result and the longer term issue of clinical restenosis. Widespread use of directional coronary atherectomy to treat lesions that would be well treated by angioplasty in an attempt to decrease restenosis rates substantially does not appear indicated by the data. In individual lesions, directional atherectomy should be selected with the view toward optimizing initial results. Further trials are needed to determine whether more aggressive or better targeted directional coronary atherectomy may improve not only the initial gain but the long-term outcome as well.

Corticosteroid agents inhibit proliferation of smooth muscle cells from human atherosclerotic arteries in vitro

We studied the in vitro effect of steroid agents on smooth muscle cells from human atherosclerotic arteries. Recent advances in the understanding of the biology of restenosis indicate that restenosis is predominantly caused by a multifactorial stimulation of smooth muscle cell proliferation. Primary stenosing plaque material of 24 patients (aged 63 +/- 14 years) and restenosing plaque material of 7 patients (aged 65 +/- 9 years) was selectively extracted from femoral arteries by the Simpson atherectomy device. Cells were isolated by enzymatic disaggregation and identified as smooth muscle cells by positive reaction with smooth muscle alpha-actin. The steroid agents prednisolone (0.0075-750 micrograms/ml), hydrocortisone (0.0125-1250 micrograms/ml), and dexamethasone (0.0004-40 micrograms/ml) were added to the cultures. Six days after seeding the cells were trypsinized and the cell number was measured by a cell counter. All three steroid agents exhibited a significant antiproliferative effect on smooth muscle cell proliferation. At high concentrations of hydrocortisone, cytoskeletal elements of smooth muscle cells such as actin, microtubules, and vimentin, were largely altered. Our data indicate that the proliferation of smooth muscle cells from human atherosclerotic arteries in vitro can be inhibited by steroid agents and thus may open the way for local post-angioplasty treatment strategies.

Early experience of directional coronary atherectomy: clinical results, complications and histopathological findings

OBJECTIVE

To report the early experience, clinical results and histopathologic findings of Directional Coronary Atherectomy from a UK centre experienced in coronary angioplasty.

DESIGN

Prospective study of the first 45 Directional Coronary Atherectomy (DCA) procedures using the Simpson coronary atherectomy device.

RESULTS

Forty-five procedures were performed in 33 male and 5 female patients (mean age, 55.1 years). Directional Coronary Atherectomy was performed to 50 lesions (39 de novo, 11 restenosis; 44 left anterior descending, 3 right, 2 circumflex coronary arteries and 1 saphenous vein graft). Clinical and primary angiographic success was achieved in 43 of 45 cases (95.5%) and in 47 of 50 lesions (94%) after DCA alone. Before DCA the mean diameter stenosis was 88.7% (range, 50-100%) but following DCA (and percutaneous coronary angioplasty (PTCA) if necessary) the mean diameter stenosis was 3.5% (range, 0-15%; P < 0.001). Complications included occlusive dissection requiring coronary artery bypass surgery in two patients; abrupt closure of right coronary artery in one patient successfully reopened by PTCA and thrombolysis, complicated by excessive blood loss; reversible coronary artery spasm due to minor nose-cone trauma in four patients and temporary side branch loss in one patient. There were no coronary artery perforations, guide catheter complications, peripheral vascular trauma or deaths. On average 5.6 specimens (range, 1-18) were removed per case. Histology showed fibrous intimal plaque in 98%, media in 39% and adventitia in 7%. Neo-intimal hyperplasia was found in all restenosis lesions but also in 30% of de novo lesions.

CONCLUSIONS

This small initial series indicates that directional coronary atherectomy is an effective and safe procedure for the treatment of obstructive coronary artery disease in carefully selected patients. With care, a high success rate can be achieved even during a learning phase. The technique is particularly effective for morphologically complex lesions that are unfavourable for PTCA. The procedure is unlike PTCA and requires additional training if pitfalls are to be avoided, high success rates achieved and complication rates kept low.

Clinical, histologic and quantitative angiographic predictors of restenosis after directional coronary atherectomy: a multivariate analysis of the renarrowing process and late outcome

OBJECTIVES

To characterize predictors of restenosis after successful directional atherectomy, we reviewed the clinical, angiographic and procedural data obtained during 132 consecutive procedures.

METHODS

Clinical and angiographic follow-up data were obtained in a prospectively collected and consecutive series of 125 patients who underwent 132 atherectomy procedures for de novo (89%) or restenotic (11%) lesions in native coronary arteries. Restenosis was assessed clinically and by quantitative coronary angiography. A dual approach to data analysis was taken to gain insight into factors affecting the clinical outcome and vessel wall healing response. Therefore, multivariate analysis was performed to 1) determine the correlates of residual lumen diameter at follow-up (angiographic outcome), and 2) characterize the determinants of the late lumen loss (renarrowing process).

RESULTS

Clinical and angiographic follow-up data after successful atherectomy were obtained in 100% and 95%, respectively. Atherectomy achieved an acute lumen gain of 1.28 +/- 0.48 mm (mean +/- SD), resulting in a minimal lumen diameter of 2.44 +/- 0.47 mm. At follow-up, the minimal lumen diameter decreased to 1.78 +/- 0.64 mm. The angiographic restenosis rate was 28% if the traditional 50% stenosis cutoff criterion was applied. Larger vessel size and postatherectomy minimal lumen diameter and right coronary or left circumflex artery lesions were independent predictors of a larger minimal lumen diameter (angiographic outcome). Lumen loss during follow-up (renarrowing process) was independently predicted by relative lumen gain and preprocedural minimal lumen diameter.

CONCLUSIONS

In analyzing the long-term results of new interventional techniques such as directional atherectomy, the late lumen loss during follow-up (renarrowing process), which is characterized by the vessel wall healing response after an intervention, should be considered together with the residual lumen diameter at follow-up (clinical outcome). It is clear that whereas improved clinical outcome is associated with larger vessel size and postprocedural lumen diameter and non-left anterior descending artery location, greater relative gain at intervention is predictive of more extensive lumen renarrowing.

Restenosis revisited: insights provided by quantitative coronary angiography

In this editorial, the problem of restenosis after coronary balloon angioplasty and other transluminal interventions is reviewed from the perspective of quantitative coronary angiography. The review is largely based on the experience of the Thoraxcentre in the application of quantitative angiography to the study of restenosis over the past decade, with incorporation and discussion of relevant and significant contributions from other groups. Current discrepancies in the angiographic definition of restenosis are highlighted and the use of percent diameter stenosis or MLD as the measurement parameter of choice is objectively addressed. Perspectives on the pathologic paradigm of restenosis are briefly reviewed as a basis from which to evaluate quantitative angiographic information provided by various studies. Particular attention is then paid, in chronologic fashion, to discussion and elaboration of insights to the restenosis process provided by quantitative angiographic studies, which have led to the introduction of some new methodological approaches to the comparison of short- and long-term angiographic luminal changes after various interventions. A word of caution on the potential pitfalls of quantitative angiographic studies is provided and counterbalanced with a discussion of clinical correlations of quantitative angiographic measurements. Finally, a proposal is made for the application of quantitative angiographic measurements to randomized clinical trials for the purpose of comparing new interventional devices.

Lessons from intravascular ultrasonography: observations during interventional angioplasty procedures

This article reviews many of the applications of intravascular ultrasonic imaging for coronary and peripheral arterial disease. In vitro studies demonstrate an excellent correlation between ultrasound measurements of lumen and plaque cross-sectional area compared with histologic sections. In vivo clinical studies reveal the enhanced diagnostic capabilities of this technology compared with angiography. Ultrasonic imaging also permits visualization of the atherosclerotic plaque itself for the first time in vivo. In addition to accurately describing the plaque morphology, ultrasonography can identify some of the tissue characteristics of the plaque. During interventional procedures, ultrasonic imaging has been shown to be beneficial for enhanced diagnosis as well as improvement of our understanding of the mechanism of newer interventional devices such as directed atherectomy, rotational or TEC atherectomy, or excimer laser. Initial studies suggest that ultrasound guidance of intravascular stent deployment may be critical for optimizing stent placement. Randomized studies are currently in progress to determine whether the guidance provided by intravascular ultrasonic imaging will alter the results of interventional procedures so that the restenosis rate can be improved.

Balloon postdilation can safely improve the results of successful (but suboptimal) directional coronary atherectomy

This study investigates whether adjunctive balloon angioplasty can be safely used to improve acute results in cases where directional coronary atherectomy alone has provided a successful (but suboptimal) outcome. Between October 1, 1990, and October 1, 1992, directional coronary atherectomy was performed successfully in 198 of 228 lesions. Individual operators believed that most acute results were satisfactory after atherectomy alone (group I, n = 115) with a minimal lumen diameter that increased from 0.82 +/- 0.45 to 3.21 +/- 0.65 mm after atherectomy, for an acute gain in lumen diameter of 2.39 +/- 0.73 mm and a residual stenosis of 6 +/- 13%. In 42% of lesions (group II, n = 83), however, results were considered suboptimal after atherectomy alone, with a minimal lumen diameter that increased from 0.85 +/- 0.45 to 2.83 +/- 0.64 mm, a smaller acute gain of 1.96 +/- 0.72 mm, and a mean residual stenosis of 17 +/- 14% (although all residual stenoses were < 50%, 19% had a residual stenosis > 30%). Adjunctive balloon angioplasty in these group II lesions provided an additional gain of 0.34 +/- 0.38 mm, bringing the total acute gain for group II lesions to 2.32 +/- 0.78 mm and the residual stenosis to 9 +/- 13%, similar to that of group I patients who underwent atherectomy alone. This strategy resulted in a 7 +/- 13% overall residual stenosis for the study population, with no higher incidence of periprocedural complications or adverse late clinical outcomes in group II patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Complications of directional coronary atherectomy: incidence, causes, and management

An assessment of complications is essential to the evaluation of directional coronary atherectomy. Major complications--such as death, Q wave myocardial infarction, or the need for emergency bypass surgery to correct acute vessel closure--result from a variety of familiar mechanisms, including dissection, thrombosis, or guiding catheter injury. In addition, unique complications of this device, such as catheter nose cone injury or vascular perforation, may also result in severe ischemia. With prompt recognition of the cause, most ischemic complications can be successfully treated in the catheterization laboratory. Less severe complications, such as femoral vascular injury, also require recognition and appropriate treatment in order to minimize sequelae. Although several large series have now documented that the overall incidence of atherectomy complications appears similar to that reported for conventional balloon angioplasty, no direct comparisons can be made until randomized trials (such as Coronary Angioplasty Versus Excisional Atherectomy Trial [CAVEAT]) are analyzed, to control for potential demographic or lesion-specific influences on complication rates.

Results of directional coronary atherectomy during multicenter preapproval testing. The US Directional Coronary Atherectomy Investigator Group

Between 1988 and 1990, clinical testing was performed at 12 US institutions using the Simpson Coronary AtheroCath under an Investigational Device Exemption. Data on 1,069 lesions (873 patients) were analyzed and presented to the Food and Drug Administration (FDA) advisory panel in the summer of 1990, forming the basis for approval of this device in September 1990. Analysis of these preapproval data shows a primary success rate of 85% (defined as tissue removal, > or = 20% reduction in stenosis, < 50% residual stenosis after directional atherectomy, and no major complication), with somewhat higher primary success in prior restenosis and noncalcified lesions. Including the use of conventional angioplasty performed after atherectomy, the overall success rate was 92%. One or more major complications occurred in 4.9% of procedures, and included death (0.5%), nonfatal Q-wave myocardial infarction (0.9%), and emergency bypass surgery (4.0%). These complications were more frequent in right coronary, de novo, and diffuse (> 20-mm length) lesions. Six-month angiography results were available in 384 (77%) of 498 lesions eligible for follow-up when the registry closed and showed a restenosis rate (late stenosis > 50%) of 42%. The restenosis rate in both native vessels (30 vs 46%) and bypass grafts (31 vs 68%) was lower in primary (de novo) lesions compared with lesions that had developed restenosis after a prior intervention. Despite the use of prototype atherectomy catheters and still evolving procedural technique, this preapproval experience provided an important initial indication of the situations in which directional coronary atherectomy was most useful and helped set clear standards for performance of this procedure following FDA approval.

Directional coronary atherectomy: how much lumen enlargement is optimal?

Until recently, it has not been clear how much of the effect of directional coronary atherectomy is due to tissue removal per se, and whether the long-term results of the procedure are helped or harmed when the operator attempts to obtain the "near zero percent" residual stenosis of which this technique is capable. This article summarizes the findings of a series of studies that have addressed these important questions and proposes a prescription for the optimal performance of directional atherectomy. Analysis of retrieved tissue weights compared with measured increases in luminal volume shows that about half of the improvement seen after directional atherectomy results from mechanical dilation. Because this "facilitated" dilation appears to take place within the bases of the trenches created by atherectomy cuts (rather than being randomly distributed in fractures throughout the plaque substance), a larger and smoother lumen is possible compared with that seen after conventional balloon dilation. Although the recovery of deep vessel wall components (media and even adventitia) is common, it generally does not cause either acute complications (i.e., perforation) or increase the probability of subsequent restenosis. Rather, reduction in the probability of late restenosis appears to be most directly related to the ability of directional atherectomy to provide the largest acute luminal diameter safely possible, thus providing better tolerance of subsequent intimal hyperplasia before hemodynamically significant renarrowing results at the treatment site.

Histologic analysis of directional coronary atherectomy samples. A review of findings and their clinical relevance

Histologic analysis of atherectomy samples from > 400 patients who received directional coronary atherectomy at 3 separate institutions disclosed 2 major categories of tissue: atherosclerotic plaque (with or without thrombus) and intimal proliferation (hyperplasia, with or without thrombus). The predominant tissue type in atherectomy samples from native, primary, or de novo coronary artery stenoses was atherosclerotic plaque. The predominant tissue type in atherectomy samples from restenosis lesions (prior balloon angioplasty, atherectomy, or both) was intimal proliferation with variable amounts of atherosclerotic plaques (with or without thrombus). Deep vessel wall components (media, adventitia) were identified at varying frequencies. The clinical relevance of atherectomy tissue is reviewed.

Analysis of atherectomy specimens

Atherectomy specimens may be regarded as biopsy tissue excised from human vascular target lesions. Proceeding from contrary histologic findings that attribute focal hypercellularity to restenosis, and hypocellularity to chronic lesions, further analysis of atherectomy specimens was performed to study ultrastructural characteristics and functional aspects propagated by both lesion types. Transmission electron microscopy examination showed that intimal smooth muscle cells (SMCs) were the predominant cells in both primary and restenotic lesions. SMCs exhibited variable degrees of metabolic activation, typically higher in SMCs of restenotic lesions. This SMC phenotype was equally expressed when tissue samples were placed in a cell culture model. In an attempt to quantify SMC activity, proliferative as well as migratory activities of cultured cells were measured by growth curves and a computer-assisted motion analysis system, respectively. A 2- to 3-fold increase of both activity determinants was observed with SMCs cultivated from restenotic lesions compared with those from primary lesions, irrespective of their coronary or peripheral origin. Drug-induced interference of human SMC metabolic activation and antagonism to their proliferative and migratory activities may be helpful in evaluation of therapeutic concepts to prevent restenosis. The antitubulin colchicine was studied for its effect on the defined determinants. The data in vitro demonstrate that colchicine decreased proliferative and migratory activity of SMCs and caused disorganization of the cytoplasmic ultrastructure. In conclusion, electron microscopy and cell culture studies may help to shed more light on the structures and mechanisms underlying restenosis and plaque growth. Deliberate counteraction of any of the specific early events implicated in these complex pathobiologic processes may eventually become effective means to suppress restenosis and may thus result in a prophylactic as well as therapeutic treatment of the diseased vascular wall.

Restenosis after coronary angioplasty

Coronary angioplasty is used to treat coronary disease in many patients. Indications for angioplasty have expanded since it was first performed, mainly as a result of improvement in equipment and techniques. One problem with coronary angioplasty is the phenomenon of renarrowing of the treated coronary lesion, a process called restenosis. The events that constitute restenosis appear to be a universal response to the arterial wall injury of angioplasty. They are currently characterized as follows: platelet adhesion and aggregation on the damaged endothelium and within deep splits into the tunica media; release of platelet-derived growth factors; inflammation of the mechanically injured medial zone; transformation of smooth muscle cells of the tunica media after their activation by several of the growth-promoting substances; migration and proliferation of transformed smooth muscle cells, with secretion of copious amounts of extracellular matrix material; and, finally, termination of the growth process with regrowth of endothelium over the injured area. A decade of research work has helped identify clinical correlates of restenosis after coronary angioplasty procedures. This work is hindered by lack of a uniform angiographic definition of restenosis. In addition, much of the information has come from small studies, with incomplete follow-up and retrospective orientation. Nevertheless, some data are available. Patient-related correlates include male gender, unstable angina, diabetes, and continued smoking after angioplasty. Lesion-related correlates include multilesional and multivessel procedures, higher postangioplasty residual stenosis, proximal vessel location, location in the left anterior descending artery, location in a vein graft, long lesions, and total occlusions. The only consistent procedure-related correlate has been incorrect sizing of the angioplasty balloon to the treated artery. For the purposes of individual patient care, clinical correlates are not helpful. No group of variables has been found to be associated with complete freedom from restenosis, and no group is completely predictive of restenosis. All patients undergoing angioplasty procedures require some follow-up through subsequent months and years. Symptom status and the results of noninvasive studies have been investigated for purposes of follow-up. Symptoms are virtually useless by themselves for predicting restenosis or its absence. When symptom status is combined with exercise thallium 201 scintigraphy performed 4 to 6 months after an angioplasty procedure, the two factors are less than ideal but have a negative predictive value of more than 90%. This means that more than 90% of patients who have neither symptoms nor evidence of ischemia by thallium 201 scintigraphy will not have angiographic restenosis.(ABSTRACT TRUNCATED AT 400 WORDS)

A comparison of directional atherectomy with coronary angioplasty in patients with coronary artery disease. The CAVEAT Study Group

BACKGROUND

Directional coronary atherectomy is a new technique of coronary revascularization by which atherosclerotic plaque is excised and retrieved from target lesions. With respect to the rate of restenosis and clinical outcomes, it is not known how this procedure compares with balloon angioplasty, which relies on dilation of the plaque and vessel wall. We compared the rate of restenosis after angioplasty with that after atherectomy.

METHODS

At 35 sites in the United States and Europe, 1012 patients were randomly assigned to either atherectomy (512 patients) or angioplasty (500 patients). The patients underwent coronary angiography at base line and again after six months; the paired angiograms were quantitatively assessed at one laboratory by investigators unaware of the treatment assignments.

RESULTS

Stenosis was reduced to 50 percent or less more often with atherectomy than with angioplasty (89 percent vs. 80 percent; P < 0.001), and there was a greater immediate increase in vessel caliber (1.05 vs. 0.86 mm, P < 0.001). This was accompanied by a higher rate of early complications (11 percent vs. 5 percent, P < 0.001) and higher in-hospital costs ($11,904 vs $10,637; P = 0.006). At six months, the rate of restenosis was 50 percent for atherectomy and 57 percent for angioplasty (P = 0.06). However, the probability of death or myocardial infarction within six months was higher in the atherectomy group (8.6 percent vs. 4.6 percent, P = 0.007).

CONCLUSIONS

Removing coronary artery plaque with atherectomy led to a larger luminal diameter and a small reduction in angiographic restenosis, the latter being confined largely to the proximal left anterior descending coronary artery. However, atherectomy led to a higher rate of early complications, increased cost, and no apparent clinical benefit after six months of follow-up.

A comparison of directional atherectomy with balloon angioplasty for lesions of the left anterior descending coronary artery

BACKGROUND

Restenosis is a major limitation of coronary angioplasty. Directional coronary atherectomy was developed with the expectation that it would provide better results than angioplasty, including a lower rate of restenosis. We undertook a randomized, multicenter trial to compare the rates of restenosis for atherectomy and angioplasty when used to treat lesions of the proximal left anterior descending coronary artery.

METHODS

Of 274 patients referred for first-time, non-surgical revascularization of lesions of the proximal left anterior descending coronary artery, 138 were randomly assigned to undergo atherectomy and 136 to undergo angioplasty; 257 of 265 eligible patients (97 percent) underwent follow-up angiography at a median of 5.9 months. Computer-assisted quantitative measurements of luminal dimensions were determined from the angiograms obtained before and immediately after the procedure and at follow-up. The primary end point of restenosis was defined as stenosis of more than 50 percent of the vessel's diameter at follow-up.

RESULTS

Quantitative analysis showed that the procedural success rate was higher in patients who underwent atherectomy than in those who had angioplasty (94 percent vs. 88 percent, P = 0.061); there was no significant difference in the frequency of major in-hospital complications (5 percent vs. 6 percent). At follow-up, the rate of restenosis was 46 percent after atherectomy and 43 percent after angioplasty (P = 0.71). Despite a larger initial gain in the minimal luminal diameter with atherectomy (mean [+/- SD], 1.45 +/- 0.47 vs. 1.16 +/- 0.44 mm; P < 0.001), there was a larger late loss (0.79 +/- 0.61 vs. 0.47 +/- 0.64 mm; P < 0.001), resulting in a similar minimal luminal diameter in the two groups at follow-up (1.55 +/- 0.60 vs. 1.61 +/- 0.68, P = 0.44). The clinical outcomes at six months were not significantly different between the two groups.

CONCLUSIONS

The role of atherectomy in percutaneous coronary revascularization remains to be fully defined. However, as compared with angioplasty, atherectomy did not result in better late angiographic or clinical outcomes in patients with lesions of the proximal left anterior descending coronary artery.