Influence of balloon size and stenosis morphology on immediate and delayed elastic recoil after percutaneous transluminal coronary angioplasty

Rotational Atherectomy Versus Intravascular Lithotripsy for Calcified In-Stent Restenosis: A Single-Center Study With 1-Year Follow-Up

Although rotational atherectomy (RA) and intravascular lithotripsy (IVL) have been proved to be effective for calcified de novo coronary lesions, their use in patients with in-stent restenosis (ISR) is still controversial. No comparison of these techniques in patients with ISR has been published so far. We sought to evaluate safety and feasibility of RA and IVL in patients with calcified ISR. Furthermore, we aimed to compare in-hospital and 1-year clinical outcomes between both groups. This is a retrospective single-center study evaluating patients with calcified ISR treated with RA (between 2012 and 2021) and IVL (between 2019 and 2021). Inhospital and 1-year clinical outcomes were compared between IVL and RA patients. In total, 28 patients with ISR who underwent RA were compared with 24 ISR subjects after IVL. The procedural success rate was 100% in both the groups. Quantitative coronary analysis demonstrated a similar degree of stenosis prior (66.4 ± 11.4 vs 68.8 ± 19.7, p = nonsignificant [NS]), and after the procedure (21.5 ± 20.5 vs 22.8 ± 12.1, p = NS) with no difference in acute luminal gain (1.34 ± 0.60 vs 1.38 ± 0.59, p = NS). There was one in-hospital major adverse cardiovascular event in the RA group. At 1-year follow-up, no difference was observed with respect to major adverse cardiovascular event rate (14.3% vs 16.7%, p = NS) and target vessel revascularization (7.1% vs 12.5%, p = NS). In conclusion, RA and IVL are safe and feasible techniques for calcified ISR yielding comparable results at 1-year follow-up. Further clinical studies are warranted to confirm our findings and shed more light on patient and lesion characteristics associated with the best outcomes.

Influence of balloon design, plaque material composition, and balloon sizing on acute post angioplasty outcomes: An implicit finite element analysis

In this work we propose a generic modeling approach for simulating percutaneous transluminal angioplasty (PTA) endovascular treatment, and evaluating the influence of balloon design, plaque composition, and balloon sizing on acute post-procedural outcomes right after PTA, without stent implantation. Clinically-used PTA balloons were classified into two categories according to their compliance characteristics, and were modeled correspondingly. Self-defined elastoplastic constitutive laws were implemented within the plaque and artery models, after calibration based on experimental and clinical data. Finite element method (FEM) implicit solver was used to simulate balloon inflation and deflation. Besides balloon profile at max inflation, results are mainly assessed in terms of the elastic recoil ratio (ERR) and lumen gain ratio (LGR) obtained immediately after PTA. No variations in ERR nor LGR values were detected when the balloon design changed, despite the differences observed in their profile at max inflation. Moreover, LGR and ERR inversely varied with the augmentation of calcification level within the plaque (-11% vs. +4% respectively, from fully lipidic to fully calcified plaque). Furthermore, results showed a direct correlation between balloon sizing and LGR and ERR, with noticeably higher rates of change for LGR (+18% and +2% for LGR and ERR respectively for a calcified plaque and a balloon pressure increasing from 10 to 14 atm). However a larger LGR comes with a higher risk of arterial rupture. This proposed methodology opens the way for evaluation of angioplasty balloon selections towards clinical procedure optimization.

The influence of angioplasty balloon sizing on acute post-procedural outcomes: a Finite Element Analysis

Atherosclerosis is one of the most common vascular pathologies in the world. Among the most commonly performed endovascular treatments, percutaneous transluminal angioplasty (PTA) has been showing significantly positive clinical outcomes. Due to the complex geometries, material properties and interactions that characterize PTA procedures, finite element analyses of acute angioplasty balloon deployment are limited. In this work, finite element method (FEM) was used to simulate the inflation and deflation of a semi-compliant balloon within the 3D model of a stenosed artery with two different plaque types (lipid and calcified). Self-defined constitutive models for the balloon and the plaque were developed based on experimental and literature data respectively. Balloon deployment was simulated at three different inflation pressures (10, 12 and 14 atm) within the two plaque types. Balloon sizing influence on the arterial elastic recoil obtained immediately after PTA was then investigated. The simulated results show that calcified plaques may lead to higher elastic recoil ratios compared to lipid stenosis, when the same balloon inflation pressures are applied. Also, elastic recoil increases for higher balloon inflation pressure independent of the plaque type. These findings open the way for a data-driven assessment of angioplasty balloon sizing selection and clinical procedures optimization.Clinical Relevance- The FE model developed in this work aims at providing quantitative evaluation of recoil after balloon angioplasty. It may be useful for both manufacturers and clinicians to improve efficiency of angioplasty balloon device design and sizing selection with respect to plaque geometry and constitution, consequently enhancing clinical outcomes.

Failure of prolonged dilation to improve long-term patency of femoropopliteal artery angioplasty: results of a prospective trial

PURPOSE

To determine long-term patency of femoropopliteal artery percutaneous transluminal angioplasty (PTA) in a prospective trial during which prolonged balloon inflation was used for optimization of initial results.

MATERIALS AND METHODS

Femoropopliteal PTA was performed in 112 limbs of 97 patients. The mean total length of the treated segments was 7.2 cm (95% CI: 5.99-8.46; median: 5.5 cm). In cases of unsatisfactory primary results after standard dilation for 1-3 minutes, the procedure was continued with prolonged dilation (93 limbs; mean balloon inflation time: 31 min; 95% CI: 24.2-37.7; median: 15 min) with use of the same balloon catheter (77 limbs) or a perfusion balloon catheter (35 limbs). Thirty-four proximal infrapopliteal artery stenoses were treated to improve peripheral runoff and 12 short stents were placed because of flow-limiting dissections.

RESULTS

Primary hemodynamic success established by Doppler ultrasound (US) criteria was achieved in 92.9% (104 of 112) of the limbs. Three major complications were encountered; none were related to prolonged balloon inflation. The primary patency rate according to Kaplan-Meier analysis was 42% (+/-5% SE) at 1 year and 39% (+/-5%) at 2 and 3 years. The corresponding secondary patency rates were 51% (+/-5%) and 47% (+/-5%). Large numbers of diseased vessels in the treated limb (four to 10 instead of one to three), eccentric lesions (as opposed to concentric morphology), and additional treated segments (instead of only femoropopliteal lesions) were associated with poorer long-term patency. The duration of balloon dilation was not a determinant of long-term patency.

CONCLUSION

Although prolonged dilation is safe and feasible in femoropopliteal artery PTA, its routine use is not warranted because it does not result in superior long-term patency rates.

Oestrogen attenuates coronary vasoconstriction after angioplasty: role of endothelin-1

BACKGROUND AND AIMS

There were controversies as to whether endothelin-1 is released after coronary angioplasty. We sought to determine whether endothelin-1 is released after coronary angioplasty and whether oestrogen administration can affect coronary vasomotor tone by reducing endothelin-1 concentrations.

METHODS

The study was designed to prospectively investigate 24 consecutive patients scheduled for elective coronary angioplasty. Patients were randomized into two groups according to whether they did not (group 1, n = 12) or did (group 2, n = 12) have intracoronary treatment with oestrogen. Quantitative coronary angiography was monitored at baseline, immediately after successful angioplasty, and 15 min after the last deflation. Blood samples for measuring the levels of endothelin-1 were drawn from the ascending aorta and the coronary sinus simultaneously before angioplasty and 15 min after balloon dilatation.

RESULTS

The diameters of the coronary artery at the dilated segments were significantly reduced 15 min after dilation compared with those immediately after dilation in group 1 from 3.20 +/- 0.22 to 2.30 +/- 0.23 mm (P < 0.001), respectively. The vasoconstriction was significantly blunted in group 2. The endothelin-1 levels from the coronary sinus rose significantly, by 29%, 15 min after angioplasty in group 1, which was attenuated after administering oestrogen. Significant correlation was found between the changes of coronary vasomotion of the dilated segment and endothelin-1 levels (r = 0.70, P = 0.01).

CONCLUSION

Endothelin-1 is released into the coronary circulation after angioplasty, and this vasoactive substance may contribute to the occurrence of vasoconstriction. The vasoconstriction is attenuated by oestrogen by reducing the endothelin-1 levels. This finding provided a new strategy to treat coronary vasoconstriction after angioplasty.

Quantification of elastic recoil after balloon angioplasty in the iliac arteries

PURPOSE

Elastic recoil of the arterial wall has been shown to be responsible for a significant loss of luminal area after balloon angioplasty in the coronary arteries, but it has not been well studied in the peripheral arteries. Because elastic recoil depends on the presence of elastin in the arterial wall, and the amount of elastin varies by artery and proximity to the aorta, the importance of this response to angioplasty may be different in peripheral arteries. The purpose of this study is to document the degree of elastic recoil in the iliac arteries, and analyze variables that might influence the results.

MATERIALS AND METHODS

A series of 19 patients with 25 iliac artery stenoses underwent balloon angioplasty followed by placement of a Palmaz stent with the same-sized angioplasty balloon. The minimum luminal diameter of the lesion was measured before treatment, immediately after balloon angioplasty, and again after stent placement. The arterial diameter after stent placement was defined as the diameter of the inflated balloon. The degree of recoil was correlated with nine variables: patient age and sex, lesion location and length, lesion severity (as percent stenosis), the balloon:artery ratio, and three factors related to lesion morphology--complex versus simple, eccentric versus concentric, and calcified versus noncalcified.

RESULTS

Elastic recoil averaged 36% +/- 11% and ranged from 19% to 54% in this series of patients. The only variable that significantly influenced the degree of elastic recoil was the balloon:artery ratio (P =.039), which was directly related.

CONCLUSION

Elastic recoil is a significant limitation of balloon angioplasty in the iliac arteries. This study illustrates the importance of techniques that limit recoil, such as vascular stents, in angioplasty of the iliac arteries.

Histopathologic evaluation of coronary artery thrombi obtained by directional coronary atherectomy in patients with restenosis-induced unstable angina pectoris

The pathogenesis of unstable angina pectoris (UAP) following percutaneous transluminal coronary angioplasty (PTCA) or directional coronary atherectomy (DCA) has not been adequately investigated, so the present study aimed to determine whether thrombi are present in restenotic lesions. The study group comprised 14 patients (16 arterial branches) with angina pectoris in whom either PTCA or DCA was performed and who had developed UAP associated with restenosis, and who then underwent DCA of the restenosed lesion (R-UAP group). The control groups comprised individuals with UAP undergoing DCA with no prior history of PTCA or DCA (P-UAP group; n=29, 29 branches), patients with acute myocardial infarction (AMI group; n=34, 34 branches), and patients with stable angina pectoris (SAP group; n=31, 33 branches). The presence of thrombi was determined by light microscopy of histologic specimens. Thrombus was present in only 1 of the 16 (6.3%) branches in the R-UAP group. 21 of the 29 (72.4%) branches in the P-UAP group, and in 25 of the 34 (73.5%) in the AMI group. In the SAP group, it was detected in only 2 of the 33 (7.1%) branches. The incidence of thrombus was significantly lower in the R-UAP group than in the P-UAP group. In conclusion, the role of thrombus is limited in causing post-interventional UAP at restenosed sites.

Pharmacologic effects of calcium channel blockers on restenosis

The understanding and control of the healing process after percutaneous transluminal coronary angioplasty (PTCA) and of the pathogenesis of restenosis are incomplete. To date, only stent implantation has been shown to successfully reduce the rate of restenosis. Calcium channel blockers have positive effects on a number of processes that may be associated with restenosis, including reduction of platelet aggregation, minimization of vasospasm, and inhibition of mitogens. Clinical trials have therefore been performed to assess the effect of calcium channel blockers on restenosis and ischemia. A meta-analysis of five restenosis trials investigating calcium channel blockers demonstrated a 30% reduction in the risk for restenosis. The Coronary Angioplasty Amlodipine Restenosis Study (CAPARES) is therefore assessing the effect of amlodipine, a long-acting, third-generation calcium channel blocker in angioplasty patients. Therapy (amlodipine 5 mg with a forced titration to 10 mg once daily, or placebo), is begun 2 weeks before angioplasty and is continued for 4 months after the procedure. The rationale of CAPARES is that amlodipine may offer anti-ischemic protection before, during, and after angioplasty, may have more beneficial effects on restenosis and various clinical end points than calcium channel blockers used in previous trials, and may improve the long-term outcome of PTCA therapy.

Matrix metalloproteinases and coronary artery disease: a novel therapeutic target

Matrix metalloproteinases (MMP) are a family of enzymes that selectively digest individual components of the extracellular matrix. Their function has been studied in both normal physiologic processes and pathologic states. In the blood vessel, MMPs play an important role in maintaining the vessel's integrity by breaking down extracellular matrix while new matrix is being synthesized. This is necessary to avoid weakening from continuous mechanical stresses. However, in certain environments, these MMPs may contribute to cardiovascular pathologic processes. The purpose of this review is to first discuss the role of MMPs in coronary vascular disease. Evidence suggests that MMPs contribute to the development of de novo atherosclerotic plaques and postangioplasty restenotic plaques by allowing smooth muscle cells to migrate from the vascular media to the intima. Evidence also suggests that MMPs contribute to the rupture of these plaques by degrading the fibrous cap that surrounds them. With this increased molecular information that concerns the pathogenesis of coronary vascular disease, new molecular therapies aimed at altering these processes are being investigated. The rationale, mode of delivery, and prospects for success of these therapies will also be discussed here.

Exaggerated luminal loss a few minutes after successful percutaneous transluminal coronary angioplasty in patients with recent myocardial infarction compared with stable angina: an intracoronary ultrasound study

This study investigates the mechanisms of exaggerated acute luminal loss after successful coronary angioplasty in patients with recent myocardial infarction compared with stable angina by angiography and intracoronary ultrasound (ICUS). We studied 15 consecutive patients (group 1) who, after a successful thrombolysis for myocardial infarction, underwent delayed (8 +/- 2 days after the myocardial infarction) successful balloon coronary angioplasty. Group 1 patients were individually matched with 15 stable angina patients (group 2). The percentage of stenosis and acute luminal loss were measured by quantitative coronary analysis. The ultrasound characteristics of lumen pathology were described as soft, hard, calcified, eccentric, concentric, thrombotic, and dissection lesions. Matching by stenosis location, reference diameter, sex, and age resulted in 2 comparable groups of 15 lesions with identical baseline characteristics. Immediately after percutaneous transluminal coronary angioplasty (PTCA), the minimal luminal diameter increased from 0.5 +/- 0.3 mm to 2.4 +/- 0.3 mm and from 0.5 +/- 0.2 mm to 2.4 +/- 0.3 mm in groups 1 and 2, respectively. Similar balloon sizes were used in both groups. The acute luminal loss (the difference between the maximal dilated balloon diameter and the minimal luminal diameter) immediately after PTCA was 0.4 +/- 0.2 mm and 0.3 +/- 0.3 mm (14 +/- 8% and 10 +/- 11% of balloon size) (P = not significant [NS]) in groups 1 and 2, respectively. After ICUS (mean 24 min after the last balloon deflation), the acute luminal loss was 0.9 +/- 0.3 mm and 0.5 +/- 0.4 mm (29 +/- 11% and 17 +/- 8% of balloon size) (P = 0.01) in groups 1 and 2, respectively. There was a significantly higher prevalence of intracoronary thrombus formation as detected by ICUS in group 1 compared with group 2 (80% vs. 20%; P < 0.001). In matched groups of successfully treated coronary angioplasty, patients with recent myocardial infarction had a similar magnitude of acute gained luminal loss immediately after the procedure. However, an exaggerated luminal loss a few minutes after the last balloon deflation in patients with recent myocardial infarction was noted because of mural thrombus formation compared with patients with stable angina.

Improved procedural results of coronary angioplasty with intravascular ultrasound-guided balloon sizing: the CLOUT Pilot Trial. Clinical Outcomes With Ultrasound Trial (CLOUT) Investigators

BACKGROUND

Indiscriminate use of balloons larger than the angiographic reference segment lumen results in high rates of ischemic complications after percutaneous transluminal coronary angioplasty (PTCA). We hypothesized that angiographically unsuspected atheromatous remodeling with vessel expansion (the Glagov phenomenon) at and adjacent to PTCA target lesions would safely accommodate oversized balloons in selected patients undergoing PTCA with intravascular ultrasound (IVUS) guidance.

METHODS AND RESULTS

After angiographically guided PTCA of 104 lesions in 102 patients, IVUS was performed, and if atheromatous remodeling was present, PTCA was repeated with larger balloons sized halfway between the lumen and external elastic membrane. Plaque occupied a mean of 51+/-15% of the angiographically "normal" reference segments. Further balloon upsizing by 0.25 to 1.25 mm was therefore performed in 76 lesions (73%), increasing the nominal balloon-to-artery ratio from 1.12+/-0.15 after standard PTCA to 1.30+/-0.17 after IVUS-guided PTCA (P<.0001). As a result, the angiographic minimal luminal diameter further increased from 1.95+/-0.49 to 2.21+/-0.47 mm, the % diameter stenosis fell from 28+/-15% to 18+/-14%, and the IVUS lumen area rose from 3.16+/-1.04 to 4.52+/-1.14 mm2 (all P<.0001). The incidence of angiographic dissection was not increased after IVUS-guided balloon upsizing (37% versus 40%, P=.67), and major complications occurred in only 2 patients (1.9%).

CONCLUSIONS

The demonstration by IVUS of atheromatous remodeling permits the safe use of balloons traditionally considered oversized, resulting in significantly improved luminal dimensions without increased rates of dissection or ischemic complications.

Comparison of myocardial perfusion reserve before and after coronary balloon predilatation and after stent implantation in patients with postangioplasty restenosis

BACKGROUND

Stents provide a scaffold for coronary arteries after angioplasty and inhibit elastic recoil.

METHODS AND RESULTS

In 25 patients with postangioplasty restenosis of the left anterior descending artery, ECG-gated digital subtraction coronary angiograms were recorded at baseline and during hyperemia (12 mg papaverine IC) before and after balloon predilatation (PTCA), after implantation of a Palmaz-Schatz stent, and after 6 months. Densitometric evaluation revealed different time and density parameters to calculate two definitions of myocardial perfusion reserve (MPR1 and MPR2) and maximum flow ratio (MaxFR). Poststenotic MPR1 increased from 1.57 +/- 0.14 to 2.59 +/- 0.86 after PTCA and to 3.10 +/- 0.41 after stenting, with 2.90 +/- 0.65 at follow-up (ANOVA, P < .05), while reference MPR1 remained unchanged at 3.10 +/- 0.40. Poststenotic MPR2 increased from 1.36 +/- 0.28 to 2.50 +/- 1.20 and to 3.40 +/- 0.58, respectively, with 3.20 +/- 0.92 at follow-up (ANOVA, P < .05), while reference MPR2 remained unchanged at 3.40 +/- 0.60. MaxFR was 2.13 +/- 0.53 after PTCA, elasticity 2.83 +/- 0.35 after stenting, and 2.73 +/- 0.58 at follow-up (ANOVA, P < .05). A good correlation was found between minimal stenotic luminal diameter and MPR1 or MPR2 (r = .87 and r = .94) and between luminal gain and MaxFR (r = .75). A negative correlation was measured between recoil and MPR1, MPR2, and MaxFR (r = -.80, r = -.86, and r = -.83). At follow-up, a steeper correlation was found between MPR and minimal stenosis diameter (MPR1: slope, 0.52 versus 0.91; MPR2: slope, 1.48 versus 1.95) and between MaxFR and net lumen gain (slope, 0.78 versus 1.27).

CONCLUSIONS

Coronary stent implantation in patients with postangioplasty restenosis normalized poststenotic myocardial perfusion immediately as a result of a larger postprocedural lumen and a more pronounced inhibition of elastic recoil. After 6 months this benefit was sustained despite progressive lumen loss.

Incidence and treatment of elastic recoil occurring in the 15 minutes following successful percutaneous transluminal coronary angioplasty

This study was performed (1) to assess the incidence and magnitude of elastic recoil occurring within 15 minutes of successful coronary angioplasty, and (2) to determine the effect of subsequent additional balloon inflations on coronary luminal diameter in patients displaying substantial recoil. The coronary angiograms of 50 consecutive patients who underwent a successful percutaneous transluminal coronary angioplasty were analyzed using computer-assisted quantitative analysis. The patients were divided into 2 groups based on the magnitude of early elastic recoil following angioplasty: those with < or = 10% (group I, n = 30) and those with > 10% (group II, n = 20) loss of minimal luminal diameter as assessed by comparing the angiogram obtained immediately after successful angioplasty with that obtained 15 minutes later. The 2 groups were similar in clinical, angiographic, and procedural characteristics. Of the 20 group II subjects, 18 (90%) underwent repeat balloon dilatations, and 2 patients (10%) had no further intervention. After additional balloon inflations were performed in these 18 patients, 16 (90%) had a final result with < 10% loss of minimal luminal diameter 15 minutes later. In conclusion, elastic recoil 15 minutes after apparently successful percutaneous transluminal coronary angioplasty is frequent, occurring in approximately 40% of patients, and is attenuated in 90% of subjects with additional balloon inflations. The resultant larger lumen diameter may exert a salutary effect on long-term outcome.

Influence of vessel dilatation on restenosis after successful percutaneous transluminal coronary angioplasty

The aim of this study was to evaluate the influence of vessel dilation on restenosis after successful percutaneous transluminal coronary angioplasty (PTCA) on the basis of quantitative angiographic analysis. To have the best comparison possible, we restrospectively studied a homogenous series of patients from the early 1980s treated according to a standardized PTCA procedure. The study group consisted of 86 patients with stable angina pectoris and single-vessel disease, all of whom underwent successful PTCA for a short concentric lesion in proximal vessel parts. The overall restenosis rate was 27%. Angiographically measured balloon size remained below specifications. The size of the inflated balloon at the site of minimal lumen diameter averaged 2.6 +/- 0.5 mm, and nominal balloon size was 3.3 +/- 0.4 mm (p < 0.001). In 22 patients with an oversized balloon (mean balloon/artery ratio 1.1 +/- 0.16) the restenosis rate was 5% compared with 34% in the corresponding group (p = 0.02). Minimal lumen diameters that were similar after the procedure (2.4 +/- 0.3 vs 2.3 +/- 0.4, NS) were 2.3 +/- 0.4 mm and 1.8 +/- 0.7 mm, respectively, at follow-up (p = 0.002). Multivariate analysis revealed balloon/vessel size ratio (p < 0.001), postprocedure diameter stenosis (p = 0.02), and percentage diameter increase produced by PTCA (p = 0.04) as independent correlates of the late outcome. Postangioplasty minimal lumen diameter was not related to restenosis. The strongest and most significant predictor of late PTCA outcome both by univariate and multivariate analysis was balloon/vessel size ratio, especially when balloon expansion at the site of minimal lumen diameter was regarded. In patients with continued success at follow-up, the ratio was 0.81 +/- 0.15 compared with 0.60 +/- 0.11 in patients with restenosis (p < 0.001). Our results suggest that the late angiographic outcome of PTCA is strongly influenced by procedural factors. It appears that in a selected group of patients, an increased balloon/artery ratio, supposedly associated with increased vessel wall stretch, favorably affects the restenosis process.

Angioplasty balloon compliance: can in vivo size be predicted from in vitro pressure profile measurements?

BACKGROUND AND HYPOTHESIS

This study was undertaken to determine whether the behavior of angioplasty balloons within coronary arteries may differ from that anticipated from data provided by the manufacturers. In particular, the in vitro pressure-diameter profiles may not truly represent in vivo sizes.

METHODS

Thus, we assessed the degree of correlation of in vitro with in vivo measurements obtained during routine angioplasty practice. In vivo size of 2.5 mm compliant (n = 8) and 3 mm semicompliant (n = 8) balloons was assessed using quantitative angiography for first, second, and third inflations.

RESULTS

In vivo size was less than expected from in vitro measurements. In general balloon diameter increased with inflation pressures up to 8 atmospheres, and some degree of elastic recoil was evident with both balloon types after the last inflation.

CONCLUSION

In vivo balloon size may not be accurately predicted from manufacturers' published data. Size is more likely to be affected by factors such as lesion characteristics and elasticity of the vessel wall than by balloon material compliance characteristics.

Influence of expanded balloon diameter on Palmaz-Schatz stent recoil

After successful stent implantation, the residual luminal diameter of the stented vessel is usually smaller than the maximal stent-expanded balloon diameter. The goal of this study was to determine whether immediate vessel diameter recoil after Palmaz-Schatz stenting is affected by the final expanding balloon diameter used during stent deployment. Single Palmaz-Schatz balloon expandable stents were successfully placed in 108 stenotic lesions. There were 68 patients with 75 saphenous vein graft (SVG) and 30 patients with 33 native coronary artery lesions, including 26 restenotic and 82 de novo occlusive (> 50% diameter stenosis) lesions. Quantitative coronary angiography was used for the assessment of stent recoil, defined as the difference between the minimal diameter of the fully expanded balloon and the postprocedure minimal lumen diameter divided by minimal diameter of the fully expanded balloon. A strong correlation (r = 0.94) was found between the minimal diameter of the fully expanded balloon and poststenting minimal lumen diameter. Immediate recoil was 11.3 +/- 7.5%, responsible on an average for 0.4 +/- 0.2-mm acute lumen loss. Recoil was less in SVG than in coronary arteries (9.7 +/- 6.6% vs. 14.0 +/- 7.8%; P = 0.004, and 0.3 +/- 0.2 vs. 0.4 +/- 0.2 mm; p = 0.01). Lesions were divided into four subgroups, based on the final stent expanding balloon diameter: (1) < or = 3.0 mm (n = 33); (2) > 3 < or = 3.5 mm (n = 43); (3) > 3.5 < or = 4 mm (n = 23); and (4) > 4 mm (n = 9).(ABSTRACT TRUNCATED AT 250 WORDS)

Importance of immediate and very early postprocedural angiographic and thallium-201 single photon emission computed tomographic perfusion measurements in predicting late results after coronary intervention

We examined prospectively the hypothesis that the adequacy of initial dilatation may be a major determinant of the late result of coronary angioplasty and that a better assessment of initial dilatation can be made from a combined angiographic and perfusion study than from angiography alone. Angiographic and perfusion (thallium-201 single-photon-emission computed tomography) measurements were made very early (18 to 24 hours) after coronary angioplasty in 59 patients (67 lesions) and also immediately (37 +/- 16 minutes) after the procedures in 19 of them (23 lesions). The early measurements, singly, in combination, and as a restenosis index (restenosis index = thallium-201 ischemic score (units) - minimal luminal area (squared millimeters) were examined as predictors of the late angiographic result. At late angiography (5.5 +/- 2.2 months after angioplasty), residual stenosis was related to the immediate and very early postangioplasty minimal luminal dimension, thallium-201 ischemic score, and restenosis index, and also to day-1 loss and lesion length. The combination of a normal result in the immediate or early thallium-201 perfusion study with a large ( > or = 2 mm) angiographic luminal dimension stratified a group of patients with better long-term results after angioplasty and a lower incidence of late restenosis (p = 0.03). The findings emphasize the importance of the initial procedure as a determinant of the late result of angioplasty.

Spontaneous regression of restenosis: an angiographic study

OBJECTIVES

This study was designed to examine the possibility that spontaneous regression in stenosis severity occurs over time in patients with restenosis after percutaneous transluminal coronary angioplasty.

BACKGROUND

The underlying mechanisms of restenosis are intimal hyperplasia and smooth muscle cell proliferation in response to vascular injury. We hypothesized that the initial hyperplastic response is followed by dynamic remodeling and eventual spontaneous regression, leading to stabilization or a reduction in stenosis severity.

METHODS

A total of 136 patients participated in a trial to evaluate the efficacy of fish oil versus placebo in preventing restenosis after angioplasty. One hundred thirteen patients completed this study with angiographic follow-up, of whom 56 had restenosis. Of these, 19 were asymptomatic and did not undergo repeat revascularization; 15 consented in a separate study to undergo repeat angiography, which was performed 6 to 25 months later to assess the possibility of regression.

RESULTS

There was a significant mean (+/- SD) decrease in lesion severity from 66.9 +/- 8.7% to 47.5 +/- 9.0% (p < 0.0001) and a significant mean increase in minimal lumen diameter from 0.91 +/- 0.31 mm to 1.44 +/- 0.35 mm (p < 0.0001). No patient showed progression of stenosis, but regression of restenosis, defined as a decrease in minimal lumen diameter > or = 0.2 mm, was noted in 12 of the patients.

CONCLUSIONS

Although all 15 study patients were asymptomatic, similar changes may occur in symptomatic patients. A trial of medical therapy may be appropriate in asymptomatic or mildly symptomatic patients before further interventions. This strategy would avoid unnecessary invasive procedures, prevent a "restenosis cycle" and result in significant cost savings.

Quantitative angiographic comparison of elastic recoil after coronary excimer laser-assisted balloon angioplasty and balloon angioplasty alone

OBJECTIVES

Coronary lumen changes during and after excimer laser-assisted balloon angioplasty were measured by quantitative coronary angiography, and the results were compared with the effects of balloon angioplasty alone.

BACKGROUND

Reduction of atherosclerotic tissue mass by laser ablation in the treatment of coronary artery disease may be more effective in enlarging the lumen than balloon angioplasty alone.

METHODS

A series of 57 consecutive coronary lesions successfully treated by xenon chloride excimer laser-assisted balloon angioplasty were individually matched with 57 coronary artery lesions successfully treated by balloon angioplasty alone. The following variables were measured by quantitative coronary analysis: 1) ablation by laser, 2) stretch by balloon dilation, 3) elastic recoil, and 4) acute gain.

RESULTS

Matching by stenosis location, reference diameter and minimal lumen diameter resulted in two comparable groups of 57 lesions with identical baseline stenosis characteristics. Minimal lumen diameter before excimer laser-assisted balloon angioplasty and balloon angioplasty alone were (mean +/- SD) 0.73 +/- 0.44 and 0.74 +/- 0.43 mm, respectively. Laser ablation significantly improved minimal lumen diameter by 0.56 +/- 0.44 mm before adjunctive balloon dilation. In both treatment groups, similar-sized balloon catheters (2.59 +/- 0.35 and 2.56 +/- 0.40 mm, respectively) were used. After laser-assisted balloon angioplasty, elastic recoil was 0.84 +/- 0.30 mm (32% of balloon size), which was identical to that after balloon angioplasty alone, namely, 0.82 +/- 0.32 mm (32%). Consequently, both interventions resulted in similar acute gains of 1.02 +/- 0.52 and 1.00 +/- 0.56 mm, respectively. Minimal lumen diameter after intervention was equal in both groups: 1.75 +/- 0.35 and 1.75 +/- 0.34 mm, respectively. The statistical power of this study in which a 25% difference in elastic recoil (0.2 mm) between groups was considered clinically important was 95%.

CONCLUSIONS

In matched groups of successfully treated coronary lesions, xenon chloride excimer laser ablation did not reduce immediate elastic recoil after adjunctive balloon dilation or improve the final angiographic outcome compared with balloon angioplasty alone using similar-sized balloon catheters.

Coronary vasoconstriction after percutaneous transluminal coronary angioplasty is attenuated by antiadrenergic agents

BACKGROUND

Vasoconstriction occurs after percutaneous transluminal coronary angioplasty (PTCA) along the dilated vessel. The vasomotor changes, initiated by the mechanical stretch of the stenotic region, are thought to be due to various mechanisms but whether the sympathetic nervous system plays a role in this phenomenon remains unknown.

METHODS AND RESULTS

Quantitative angiography (ARTREK) was performed in 45 patients undergoing an epicardial vessel PTCA for a stenosis of 76 +/- 1% (1) in basal conditions, (2) after PTCA, and (3) 30 minutes after PTCA (vasoconstriction). In 14 control patients, the same measurements were obtained up to 60 minutes after PTCA. Coronary diameters were measured along the PTCA vessel at the narrowest stenosis level and at a level peripheral to stenosis. In 36 patients two diameters were also measured at a proximal segment and at a distal segment along a nonmanipulated vessel. Thirty minutes after PTCA the dilated segment underwent a -31 +/- 2% (mean +/- SEM, ANOVA, P < .05) reduction in diameter when compared with PTCA values, and the segment peripheral to stenosis showed a reduction of -17 +/- 2% (P < .05). In all patients a significant vasoconstriction also was observed along the control vessel (proximal segment, -14 +/- 3%; P < .05 versus basal; and distal segment, -17 +/- 2%). At the time of maximal vasoconstriction (30 minutes after PTCA), the patients (treatment groups) received (1) 18 micrograms/kg IC phentolamine (Phe, n = 7), (2) 14 micrograms/kg IC yohimbine (YO, n = 7), (3) 16 micrograms/kg IC propranolol (Pro) followed by 18 micrograms/kg IC phentolamine (Pro+Phe, n = 7), and (4) 0.2 mg/kg IC bretylium (Bre, n = 10). In 14 patients (control groups) an intracoronary injection of warm saline was given. After drug injections, angiograms were repeated at 5-minute intervals for 20 minutes and ended after a 300-micrograms intracoronary trinitroglycerin injection. At stenosis level, Phe and Bre counteracted vasoconstriction, inducing a dilatation of +19 +/- 3% and +22 +/- 6%, respectively, while Pro+Phe caused a dilatation of +16 +/- 9% above the PTCA values (P < .05 versus PTCA). YO only partially reversed vasoconstriction (from -33 +/- 4% to -12 +/- 4%, P = NS versus PTCA). At peripheral-to-stenosis level, vasoconstriction was abolished by Phe (+26 +/- 7%, P < .05 versus basal), while it was still present after Pro+Phe (-23 +/- 2%) and Bre (-18 +/- 4%). In addition, Phe and Bre dilated the control vessel at the proximal segment (+17 +/- 6% and +8 +/- 4%, respectively, P < .05 versus basal), while YO and Pro+Phe only counteracted vasoconstriction (from -15 +/- 3% to +7.6 +/- 1% and from -16 +/- 3% to +4 +/- 5%, respectively, P = NS versus basal). At the distal segment only Phe produced a vasodilatation of +23 +/- 1%; YO counteracted constriction (from -16 +/- 2% to +9 +/- 6%, P < .05 versus basal), whereas after Pro+Phe and Bre, the vasoconstriction persisted.

CONCLUSIONS

The mechanical stretch and ischemia caused by balloon inflation induced vasoconstriction mediated by alpha-adrenergic receptors (mainly alpha 1), overcoming a beta-mediated dilatation. The use of different antiadrenergic drugs showed that Phe counteracts post-PTCA vasoconstriction, and the simultaneous use of alpha- and beta-receptor blocking agents (Pro+Phe and Bre) reveals the presence of a peripheral, predominant beta-mediated dilatation. The presence of vasoconstriction also along the control vessels not branching from the stretched ramus provides evidence for the existence of neural sympathetic vasoconstrictor reflexes.

Recoil following Wiktor stent implantation for restenotic lesions of coronary arteries

The purpose of this study was to determine acute recoil of the vessel wall immediately after Wiktor stent implantation in native coronary arteries of 77 consecutive patients and to assess whether there was compression or "late recoil" of the stent itself at long-term follow-up. Furthermore, the relationship between recoil and a number of clinical, angiographic, and procedural variables was studied in addition to the relation between acute recoil renarrowing or restenosis was assessed. All angiograms were analyzed with the Cardiovascular Angiography Analysis System using automated edge detection. Acute recoil was defined by the difference between the mean diameter of the fully expanded balloon on which the stent was mounted and the mean diameter of the stented segment. Late recoil was calculated by comparing the mean diameter of the stent itself immediately after implantation and at follow-up without opacification of the vessel. Acute recoil amounted to 0.25 +/- 0.32 mm or 8.2%. Multivariate analysis identified sex (coefficient = -0.20, p = 0.04) and stent/artery ratio (coefficient = 0.99, p = 0.0001) as the only independent predictors of acute recoil. "Late recoil" of the stent itself was not observed. The overall difference between the mean diameter of the stent itself immediately after implantation and at follow-up was -0.15 +/- 0.33 mm, suggesting an overall increase in diameter of 5.0%. There was no relation between acute recoil and late restenosis. On the contrary, there was a trend towards a greater degree of recoil in patients without restenosis. Moreover, linear regression analysis disclosed a weak but negative correlation between acute recoil and a loss in minimal luminal diameter (coefficient: -0.55, p = 0.04). The Wiktor stent effectively scaffolds the instrumented vessel. Only a minimal amount of acute recoil was noted, which did not contribute to late luminal renarrowing or restenosis. In addition, no late compression of the stent itself was observed. These data suggest that tissue ingrowth into the lumen of the stented segment is the main cause of late luminal renarrowing after stent implantation.

Vascular mechanics for the cardiologist

Many common problems in clinical cardiology are due to disturbances in vascular mechanics. The terminology and basic principles of vascular mechanics, including fundamentals of the relation of stress and strain, are described in this review. Approaches to measuring vessel wall stiffness and the mechanical basis for vascular catastrophes are introduced.

Emergency coronary stenting for dissection during percutaneous transluminal coronary angioplasty: angiographic follow-up after stenting and after repeat angioplasty of the stented segment

OBJECTIVES

The purpose of this study was to assess the angiographic results after emergency coronary stenting and after repeat angioplasty for restenosis within the stent.

BACKGROUND

There is still little angiographic information about lumen renarrowing and its correlates after emergency stenting, and data with regard to the angiographic outcome of repeat angioplasty within the stent are almost nonexistent.

METHODS

This study was based on the quantitative evaluation of angiograms performed before and immediately after intervention and at 6-month follow-up. The study included 164 of the 183 eligible patients with emergency Palmaz-Schatz stent implantation and 31 of those with restenosis within the stent who had repeat angioplasty.

RESULTS

Stenting produced an improvement in minimal lumen diameter from 0.82 +/- 0.41 to 2.76 +/- 0.47 mm (mean +/- SD) and in diameter stenosis from 74.9 +/- 11.5% to 18.3 +/- 8.1%. Elastic recoil was 0.51 +/- 0.34 mm, or 16%. At 6-month follow-up, 32.3% of the patients had restenosis (> or = 50% stenosis). Minimal lumen diameter decreased to 1.84 +/- 0.78 mm, and diameter stenosis increased to 41.7 +/- 21.0%. The degree of lumen loss correlated significantly with the length of the original stenosis and the initial lumen gain achieved by stenting. Thirty-one patients with in-stent restenosis underwent repeat angioplasty. The primary success rate was 100%, and no abrupt vessel closure was verified. Minimal lumen diameter increased from 0.85 +/- 0.35 to 2.18 +/- 0.39 mm, and diameter stenosis decreased from 69.7 +/- 12.9% to 28.6 +/- 9.4%. Elastic recoil was 0.82 +/- 0.38 mm, or 27%. At follow-up, 38.5% of the patients had restenosis. Minimal lumen diameter was reduced to 1.72 +/- 0.67 mm, and diameter stenosis increased to 42.4 +/- 18.1%.

CONCLUSIONS

Angiographic results of emergency coronary stenting compare favorably with those of conventional angioplasty. In-stent balloon redilation in patients with restenosis is associated with excellent short-term results and a restenosis rate not different from that reported for nonstented vessels.

Intracoronary stents: a review of the experience with five different devices in clinical use

Atherosclerotic cardiovascular disease remains one of the most important causes of morbidity and mortality in the industrialized world. Treatment is basically aimed at palliation and consists of either pharmacological intervention or revascularization. The first significant advances in the latter were largely surgical. However, the pressing need for treatment with less invasive and potentially less expensive techniques, have stimulated the development of nonsurgical revascularization techniques. Percutaneous transluminal coronary balloon angioplasty, which was first performed by Andreas Gruentzig in 1977, is one of the most successful examples and provided the stimulus for a rapid technological growth of interventional cardiology. It is now widely accepted as a safe and effective treatment of obstructive coronary artery disease. However, the risk of abrupt vessel closure during or immediately after the intervention and the risk of late luminal renarrowing or restenosis continue to compromise its overall safety and efficacy. To improve the immediate and long-term results of balloon angioplasty, a number of new technologies such as intracoronary stenting, directional or rotational atherectomy, and laser therapy have been developed and represent the leading edge in the battle against atherosclerosis. The purpose of this paper is to review the experience and results of the various types of stents in clinical use.

Cardiovascular applications of laser technology

Laser technology has been evaluated for the treatment of coronary artery disease, ventricular and supraventricular arrythmias, hypertrophic cardiomyopathy, and congenital heart disease. Developments in laser angioplasty, laser thrombolysis, transmyocardial laser revascularization, photochemotherapy, laser treatment of arrhythmias and/or laser diagnostics are directed at improving upon conventional non-laser approaches, and providing new therapeutic and diagnostic options. This review will summarize the current status of the multiple applications of laser technology for cardiovascular diagnosis and therapy.

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.

Usefulness of repeat coronary angiography 24 hours after successful balloon angioplasty to evaluate early luminal deterioration and facilitate quantitative analysis

Because of the unavoidable occurrence of vessel disruption after successful coronary balloon angioplasty, the reliability of quantitative angiographic analysis in that setting has been questioned. For this reason and the suggested occurrence of delayed elastic recoil, repeat angiography at 24 hours has been advocated in clinical interventional trials. In this study, these issues are confronted by performing comprehensive quantitative analysis (Cardiovascular Angiographic Analysis System) of coronary angiograms, acquired in multiple identical projections immediately after and 24 hours after angioplasty, in 102 patients with 110 successfully dilated lesions. Vasomotion was controlled by intracoronary nitrate before angiography and all patients were fully anticoagulated (activated partial thromboplastin time 85 to 120 seconds) for > 24 hours. Paired Student's t tests applied to angiographic measurements revealed that there was no significant deterioration in minimal luminal diameter or cross-sectional area from immediately after angioplasty to 24 hours later. It can thus be inferred that there is no phenomenon of delayed elastic recoil, at least during this time period. Measurement accuracy and precision of the Cardiovascular Angiographic Analysis System from the postangioplasty angiogram are highly acceptable, at < 0.01 and +/- 0.20 mm, respectively. Therefore, it is concluded that routine repeat 24-hour angiography is not indicated after successful angioplasty. A highly significant increase (p < 0.001) in reference diameter (+0.11 +/- 0.18 mm) was responsible for the apparent increase in percent diameter stenosis (2.4 +/- 7%), a finding that demonstrates the potential for error by selective application of percent diameter stenosis measurements alone. Preferential use of absolute luminal measurements is thus strongly recommended for clinical trials with angiographic monitoring.

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.

Time course of restenosis during the first year after emergency coronary stenting

BACKGROUND

Prevention of abrupt vessel closure after percutaneous transluminal coronary angioplasty (PTCA) represents one of the current indications for intracoronary stent implantation. After the procedure, the stented segment undergoes luminal changes that may lead to late restenosis. This study was undertaken to assess the time course of luminal changes during the first year after emergency placement of coronary stents.

METHODS AND RESULTS

Coronary stenting was indicated in patients with present or threatened vessel closure secondary to large dissections after PTCA. From June 1989 to May 1991, 82 patients who received Palmaz-Schatz stents and did not have early vessel occlusion after stenting were enrolled into a serial angiographic follow-up study. Coronary normal reference diameter and minimal luminal diameter were measured with an automated edge detection technique. Patients who underwent repeat PTCA for restenosis were excluded from further serial angiography. The restudy rate at 3, 6, and 12 months was 96%, 81%, and 90% of the eligible patients, respectively. The incidence of restenosis (defined as a diameter stenosis > or = 50%) was 22.0% at 3 months, 31.9% at 6 months, and 33.2% at 12 months. Minimal luminal diameter was increased from 0.66 +/- 0.32 mm before to 2.85 +/- 0.43 mm immediately after stenting. It was 0.46 +/- 0.31 mm smaller than the diameter of the maximally inflated balloon during the procedure. The reduction in minimal luminal diameter was 0.80 +/- 0.69 mm (p = 0.0001) for the first 3 months, 0.29 +/- 0.52 mm (p = 0.0001) between 3 and 6 months, and 0.13 +/- 0.32 mm (p = 0.01) for the last 6 months. The percentage of patients who presented a significant change in minimal luminal diameter (defined as > 0.60 mm) declined from 50.6% during the first 3 months and 18.9% between 3 and 6 months to 6.5% for the period between 6 and 12 months.

CONCLUSIONS

The incidence and the time course of restenosis after emergency coronary stenting are similar to that reported for conventional PTCA. Coronary lumen dimensions demonstrated a peak change at 3 months and remained mostly stable after the first 6 months.

Reliability of quantitative coronary angiography of the target lesion immediately and 1 day after coronary balloon and excimer laser angioplasty

OBJECTIVES

This prospective trial was performed to evaluate the impact of the morphologic complications of angioplasty on the reliability and results of quantitative angiographic assessment of the residual stenosis.

BACKGROUND

Postintervention quantitative coronary analysis is limited by a variety of such complications.

METHODS

In 199 patients undergoing an early control angiographic study within 24 h after coronary balloon or excimer laser angioplasty (24-h study), detailed quantitative angiographic measurements were performed on the target lesion immediately after intervention and at the 24-h study. Reproducibility of quantitative arteriography was determined by repeat measurements on the same angiogram.

RESULTS

Intraobserver/interobserver variability was significantly higher (p < 0.0001/p < 0.03) for the postintervention angiogram than for the 24-h angiogram. Patients were classified into three subgroups with respect to the occurrence of angiographic complications or chest pain after intervention. In patients with angiographic complications after balloon angioplasty alone/stand-alone laser angioplasty/laser angioplasty with adjunctive balloon dilation, a significant difference in mean minimal lumen diameter (p = 0.0001/p = 0.03/p = 0.035) was observed between the immediate postintervention and 24-h angiogram. In patients without angiographic complications or patients with recurrent chest pain undergoing balloon angioplasty, stand-alone or adjunctive laser angioplasty, mean minimal lumen diameter remained nearly unchanged (p = NS).

CONCLUSIONS

Angiographic measurements of the target lesion immediately after angioplasty were significantly less reliable than measurements obtained at 24 h after angioplasty in patients with angiographic complications. The occurrence of postintervention vascular complications was associated with significant early lesion changes between the immediate postangioplasty and the 24-h angiogram.

Influence of elastic recoil on restenosis after successful coronary angioplasty in unstable angina pectoris

The elastic behavior of the dilated coronary vessel has been reported to affect the immediate results of coronary angioplasty. To determine whether elastic recoil may also influence the long-term restenosis process, 98 consecutive patients with unstable angina and 1-vessel disease were studied. An automated coronary quantitative program was used for the assessment of balloon and coronary luminal diameters. Elastic recoil was defined as the percent reduction between minimal balloon diameter at the highest inflation pressure and minimal lesion diameter immediately after coronary angioplasty. Follow-up coronary arteriography was performed 8 to 12 months after the procedure in all patients. The mean elastic recoil averaged 17.7 +/- 16% and was correlated to the degree of residual stenosis immediately after coronary angioplasty (r = 0.64; p < 0.001). Restenosis, defined as > 50% diameter stenosis at follow-up, developed in 53 patients (54%). There was no correlation between the degree of elastic recoil and the changes in minimal lesion diameter observed during follow-up, whereas a positive correlation between the amount of elastic recoil and the incidence of restenosis was documented (r = 0.84; p < 0.05). Thus, the elastic properties of the dilated vessel do not influence the active process of restenosis. However, because elastic recoil negatively influences the initial results of angioplasty, it is more likely that further reductions in lumen diameter during follow-up can reach a threshold of obstruction considered critical for a binary definition of restenosis.

Intracoronary ultrasound assessment of directional coronary atherectomy: immediate and follow-up findings

OBJECTIVES

This study was conducted to assess the relations among intracoronary ultrasound, angiographic and histologic data obtained from patients with coronary artery disease successfully treated by directional coronary atherectomy. In addition, it was designed to elucidate whether some aspects of intravascular ultrasound or pathologic findings could predict a propensity to restenosis.

BACKGROUND

Intracoronary ultrasound is a useful technique in guiding and assessing atherectomy. However, there is little information about the characterization of the different types of coronary plaques and the changes observed in them after resection. Furthermore, the follow-up ultrasound appearance of previously treated lesions remains undepicted.

METHODS

Fifty-two patients (54 +/- 10 years old) were studied. All were successfully treated by atherectomy with the aid of intracoronary ultrasound guidance. Qualitative and quantitative ultrasound and angiographic variables were derived before and after resection. Quantitative histologic morphometric information was also obtained from the specimens. In 22 patients, a follow-up echoangiographic reevaluation was performed 6 +/- 4 months later.

RESULTS

Echogenic plaques had a higher collagen and calcium content, whereas echolucent plaques had an increased level of fibrin, nuclei and lipids. Ultrasound plaque reduction after atherectomy was greater in echolucent (76 +/- 21%) than in echogenic plaques (60 +/- 18%; p < 0.05). That reduction correlated with the weight of the resected material (r = 0.62; p < 0.01). At follow-up study, 13 of 22 patients had angiographic and ultrasound evidence of restenosis. Most recurrent lesions had a stenotic three-layer appearance. The incidence of restenosis of primary lesions treated with atherectomy was higher in echolucent (100%) than in echogenic (33%) plaques. Similarly, a higher proportion of nuclear content in the resected material was observed in patients who developed restenosis (2.1 +/- 0.7%) than in patients who had late success after atherectomy (1.2 +/- 0.6%).

CONCLUSIONS

Our findings suggest that echolucent plaques are easier to resect than are echogenic plaques but frequently develop restenosis. In contrast, the resection of echogenic plaques, although often incomplete, is associated with better long-term results.

Generalized model of restenosis after conventional balloon angioplasty, stenting and directional atherectomy

OBJECTIVES

This study was designed to extend the results of a quantitative model originally developed for restenosis after stenting or atherectomy to include restenosis after conventional balloon angioplasty.

BACKGROUND

We have previously described a continuous regression model that explains late (6-month) lumen narrowing as the difference between the immediate gain and the subsequent normally distributed late loss in lumen diameter after Palmaz-Schatz stenting or directional atherectomy.

METHODS

Lumen diameter was measured immediately before and after coronary intervention on 524 consecutive lesions including those treated by Palmaz-Schatz stenting (102), directional atherectomy (134) and conventional balloon angioplasty (288). Of these lesions, 475 (91%) underwent follow-up angiography 3 to 6 months after treatment. The immediate increase in lumen diameter produced by the intervention (immediate gain) and the subsequent reduction in lumen diameter between the time of intervention to follow-up angiography (late loss) were examined. Association between demographic or angiographic variables and continuous measures of restenosis (late lumen diameter or late percent stenosis) was tested with linear regression techniques; a traditional binary measure of restenosis (late diameter stenosis > or = 50%) was evaluated with logistic regression analysis.

RESULTS

Regression models relating late lumen diameter to the immediate lumen result were successfully fitted to all segments studied. According to these models, three indexes of restenosis (late lumen diameter, late percent stenosis and binary restenosis) were found to depend solely on the immediate lumen diameter after the procedure and the immediate residual percent stenosis, but not on the specific intervention used. Moreover, the late loss in lumen diameter was found to vary directly with the immediate gain provided by an intervention, and the "loss index" (a measure that corrects for differences in immediate gain) was uniform among all three interventions.

CONCLUSIONS

The quantitative model originally developed for restenosis after stenting or atherectomy may thus be generalized to include conventional balloon angioplasty. It shows that the apparent differences in restenosis among the three interventions studied are due solely to differences in the immediate result provided and not to differences in the behavior of subsequent late loss. Moreover, although the late loss in lumen diameter was found to correlate with differences in the immediate gain provided by an intervention, the "loss index" (a measure that corrects for differences in acute gain) was uniform across all three interventions. It is thus the immediate result (and not the procedure used to obtain that result) that determines late outcome after coronary intervention.

Comparison of acute elastic recoil after directional coronary atherectomy versus standard balloon angioplasty

We evaluated intraprocedural "elastic recoil" in 25 patients (22 men and 3 women) undergoing directional coronary atherectomy (DCA) of left anterior descending stenoses, and compared these with 25 temporally-matched (14 men and 11 women) patients having balloon angioplasties (PTCA). Quantitative arteriography was performed using the Coronary Measurement System (Leiden, The Netherlands), with "elastic recoil" defined as the difference in maximum device or balloon size minus residual minimum diameter. In addition, we determined the effects of relative device size, specific anatomic location (proximal/mid artery), lesion length, eccentricity (symmetry index), and dystrophic calcification on acute "recoil" severity after both procedures. Although initial coronary stenoses were similar (minimum stenotic diameter, DCA = 0.59 +/- 0.20 mm versus PTCA = 0.55 +/- 0.23 mm, p = NS), less "elastic recoil" was observed after atherectomy (DCA = 0.83 +/- 0.57 mm versus PTCA = 1.26 +/- 0.56 mm, p < 0.01), and this was confirmed by absolute recoil/maximum device size ratios (DCA = 23.5 +/- 16.0% versus PTCA = 41.6 +/- 13.8%, p < 0.01). Acute "elastic recoil" was also influenced by maximum device size/"normal" coronary artery ratios [(ratio < 0.9, DCA = 0.26 +/- 0.10 mm versus PTCA = 0.84 +/- 0.13 mm, p < 0.01); (ratio 0.9 to 1.1, DCA = 0.69 +/- 0.41 mm versus PTCA 0.75 +/- 0.32 mm, p = NS); (ratio > 1.1, DCA = 1.09 +/- 0.64 mm versus PTCA = 1.59 +/- 0.48 mm, p < 0.05)].(ABSTRACT TRUNCATED AT 250 WORDS)

Excimer laser coronary angioplasty for failed PTCA

Specific indications for excimer laser coronary angioplasty (ELCA) are yet undefined. We report two specific applications of ELCA when percutaneous transluminal coronary angioplasty (PTCA) failed: (1) to facilitate balloon crossing a long rigid stenosis that could not be crossed after the lesion was wired, and (2) to overcome prominent elastic recoil of the stenosis after PTCA.