Author + information
- Received May 6, 1996
- Revision received June 11, 1997
- Accepted June 21, 1997
- Published online October 1, 1997.
- Hélène Eltchaninoff, MDA,*,
- Alain Cribier, MD, FACCA,
- René Koning, MDA,
- Charles Chan, MDB,
- Valérie Sicard, MDA,
- Arthur Tan, MD, FACCB and
- Brice Letac, MD, FACCA ()
- ↵*Dr. Hélène Eltchaninoff, Hôpital Charles Nicolle, 1 rue de Germont, 76000 Rouen, France.
Objectives. This study sought to compare, by angioscopy, the morphologic changes induced by rotational atherectomy, followed by additional angioplasty, with those observed after balloon angioplasty alone.
Background. Rotational atherectomy and balloon angioplasty act by different mechanisms, which could explain the difference in morphologic changes induced by these two techniques.
Methods. The study group included 50 patients with 50 lesions who were randomly assigned to undergo rotational atherectomy (n = 24) or balloon angioplasty (n = 26). Rotational atherectomy with a single burr (≃70% of coronary diameter) was systematically followed by additional balloon angioplasty. Angioscopy was performed immediately after the procedure. Abnormal angioscopic findings were 1) flaps, graded from 1 to 3 (1 = intimal flap; 2 = flap protruding into <50% of the lumen; 3 = flap protruding into ≥50% of the lumen); 2) thrombi, graded from 1 to 3 (1 = flat deposits; 2 = protruding but nonocclusive thrombus; 3 = occlusive thrombus); 3) subintimal hemorrhage; 4) longitudinal dissection. The two groups were comparable for clinical and angiographic baseline data.
Results. On angioscopy, flaps were observed less frequently after rotational atherectomy followed by additional balloon angioplasty (8 [33%] of 24 lesions) than after balloon angioplasty alone (14 [54%] of 26 lesions, p = 0.08) and were also less severe (grade 1 in 6 lesions, grade 2 in 2 and grade 3 in none vs. grade 1 in 4 lesions, grade 2 in 5 and grade 3 in 5). Longitudinal dissections were also significantly less frequent: one versus six (p = 0.05). There was no difference in the incidence of angioscopic thrombi (p = 0.16) or subintimal hemorrhage (p = 0.15), but the power to detect a significant difference was low for these variables (37% and 26%, respectively).
Conclusions. Rotational atherectomy followed by additional balloon angioplasty leads to fewer angioscopic dissections and a trend toward fewer intimal flaps than balloon angioplasty alone. However, our angioscopic differences did not lead to an outcome difference between the two groups.
Percutaneous coronary angioscopy can provide important information with regard to coronary lesion morphology and intraluminal wall of the artery. It has been clearly demonstrated [1–3]to be superior to angiography in detecting intraluminal thrombi and dissections in patients with coronary artery disease. Previous angioscopic studies [4, 5]have shown that the majority of patients who undergo balloon angioplasty have dissection and persistence of thrombus in the target lesion. We sought to determine whether rotational atherectomy would result in the same morphologic changes as those observed after balloon angioplasty. Indeed, it has been proposed that abrasion of atheromatous tissue by rotational atherectomy would lead to lower failure, complication and restenosis rates than those observed after balloon angioplasty, which acts by pushing the atheroma aside. Ultrasound studies [6, 7]have shown that rotational atherectomy causes lumen enlargement by selective ablation of hard, especially calcified, atherosclerotic plaque, with little tissue disruption and rare arterial expansion. Very few data are available on intracoronary angioscopy after rotational atherectomy.
The aim of the present prospective, randomized study was to compare by angioscopy the morphologic changes induced by rotational atherectomy followed by additional balloon angioplasty with those observed after balloon angioplasty alone, which remains the standard technique for the treatment of coronary vessel disease.
The study group included 50 patients with 50 lesions. The protocol was approved by the ethical committee of our institution, and informed consent was obtained from all patients before the procedure. Patients were considered eligible for the study if they had stable or unstable angina with at least one lesion (>50% diameter stenosis) in a native vessel suitable for angioplasty. All types of lesions were included. Patients were excluded if they had an acute myocardial infarction within 24 h before the procedure, a restenotic lesion, a total occlusion or a vein graft lesion. The additional inclusion criteria for angioscopy were coronary artery lumen diameter between 2.5 and 3.5 mm; location of the target lesion in a straight segment of the artery; location of the lesion at least 2 cm away from the coronary ostium; absence of left main coronary artery disease.
1.2 Study protocol and randomization.
1.2.1 Phase 1.
After initial coronary angiography, each patient was randomized to undergo either rotational atherectomy (n = 24) or balloon angioplasty (n = 26). In patients assigned to rotational atherectomy, additional balloon angioplasty was systematically performed after rotational atherectomy. Coronary angiography and angioscopy of the treated lesion were performed at the end of this protocol phase. Angioscopic and angiographic findings were compared between the two groups. Angiographic success rate, percent residual stenosis and minimal lumen diameter were evaluated at that time.
1.2.2 Phase 2.
Successfully treated patients had no further dilation and received routine postangioplasty management. Patients with residual stenosis >50% or grade D1 dissection or higher went on to phase 2 and had repeat dilation, stent implantation or medical management at the discretion of the operator. Angioscopy was not repeated at the end of phase 2.
1.3 Coronary angioscopy.
We used a 4.5F Baxter coronary angioscope (Baxter Healthcare Corp.), which is an integrated design consisting of a flexible catheter jacket with an occlusion cuff at the distal end and an optical imaging bundle extendible 5 cm beyond the catheter jacket. The angioscope is advanced under fluoroscopic guidance over a 0.014-in. guide wire using a monorail system. During imaging, lactated Ringer’s solution is infused through a distal irrigation port at a rate of 0.6 ml/s by means of a Medrad power injector. The images are viewed on a television monitor and stored on 0.75-in. VHS videotapes for repeat viewing and archiving. Heart rate, guiding catheter pressure, ST segment changes, cardiac rhythm and patient symptoms were continuously monitored during the procedure.
At the beginning of the procedure, all the patients received a bolus of 10,000 IU of intravenous heparin and 150 μg of intracoronary nitroglycerin. Aspirin was routinely administered.
1.4.1 Balloon angioplasty.
Balloon angioplasty was performed by standard techniques. An 8F sheath was placed in the femoral artery. Balloon size was chosen to obtain a reference artery diameter/balloon diameter ratio close to 1.
1.4.2 Rotational atherectomy.
An 8F sheath, or 9F sheath if the diameter of the burr was >2 mm, was placed in the femoral artery. One burr was used per lesion. The size of the burr was chosen to obtain a reference artery diameter/burr diameter ratio close to 70%. Additional balloon angioplasty was systematically performed after rotational atherectomy. Balloon size was chosen to obtain a reference artery diameter/balloon diameter ratio close to 1. Low inflation pressure (<6 atm) was used. Pacemaker capability was continuously maintained for right coronary artery procedures.
1.5 Angiographic assessment.
At least two angiographic projections (orthogonal, if possible) were recorded such that they were suitable for on-line quantitative analysis by the Philips DCI automated quantitative coronary angiography system. The absolute stenosis and reference diameters were measured by the computer using the known contrast-empty guiding catheter as a scaling device. Coronary angiograms were read in the angiographic laboratory by two angioplasty operators (H.E., A.C.) who had no knowledge of the treatment assignment. Lesion morphology was classified according to the American College of Cardiology/American Heart Association classification . The presence of intracoronary thrombuswas defined as a noncalcified filling defect within the lumen, surrounded by contrast material observed in multiple projections, or the persistence of contrast material within the lumen. Angiographically visible dissectionswere defined from A to F according to modified National Heart, Lung, and Blood Institute criteria . Angiographic successwas defined as a residual stenosis ≤50% in the absence of severe coronary artery dissection (grade D1 or higher). Clinical successwas defined as angiographic success in the absence of major complications, such as death, myocardial infarction and bypass surgery . Angiographic results were assessed at the end of phase 1 and compared with the angioscopic findings.
1.6 Angioscopic assessment.
Angioscopy was performed at the end of the protocol phase (phase 1). Intraluminal changes observed after angioplasty (intimal flaps, thrombi, subintimal hemorrhage and longitudinal dissections) have been previously defined and classified . Briefly (Figs. 1 and 2), ⇓⇓
1. Intimal flap: grade 1 = small, thin and freely mobile fronds of tissue; grade 2 = large flap protruding into <50% of the lumen area; grade 3 = large flap protruding into ≥50% of the lumen area.
2. Thrombi: grade 1 = coalescent red or white mass adhering to the endothelium and only minimally raised above the surface; grade 2 = coalescent red or white mass adhering to the endothelium and protruding into but not occluding the lumen; grade 3 = occlusive thrombus.
3. Subintimal hemorrhage: large, diffuse, red plaque not protruding into the lumen.
4. Longitudinal dissection: sail-like flap without any visible intimal disruption, intermittently occluding the lumen by its billow-like action.
The angioscopic results were reviewed separately by two independent experienced physicians who were unaware of the angiographic findings and the procedure applied. In case of disagreement, a third observer (R.K.) evaluated the angioscopic image. In all cases, both observers were in agreement as to categorization of flaps, longitudinal dissections and thrombi grades 2 and 3. The observers disagreed in two cases on discrimination between a grade 1 thrombus and a hemorrhage.
1.7 In-hospital follow-up.
A standard 12-lead electrocardiogram was recorded 24 h after the procedure. Serial measurements of serum creatine kinase (CK) and CK-MB fraction were performed on the following day. The following in-hospital complications were recorded: nonfatal myocardial infarction, abrupt closure of the target vessel, repeat angioplasty of the target vessel, coronary artery bypass surgery and death.
1.8 Statistical analysis.
Differences between groups were compared by the Fisher exact test for binary variables and an independent Student ttest for continuous variables. For the test comparing the two procedures, we used one-tailed tests because we were looking at improvement with rotational atherectomy. Results are presented as mean value ± SD. A p value ≤0.05 was considered statistically significant.
The study group included 50 patients with 50 lesions. Baseline clinical and angiographic characteristics were similar in both study groups, as shown in Table 1. There was no difference in the distribution and severity of lesions in the two groups.
Procedural information is shown in Table 2. The mean diameter of the burr was 2.0 ± 0.2 mm. Preangioplasty reference diameters were similar between the two groups. Technical balloon angioplasty variables were compared between the two groups because additional balloon angioplasty was systematically performed after rotational atherectomy. Maximal balloon diameter was 3.1 ± 0.1 in the rotational atherectomy group and 3.0 ± 0.4 in the balloon angioplasty group (p = NS). Inflation time was shorter in the rotational atherectomy group (253 ± 148 s) than in the balloon angioplasty group (370 ± 153 s), p = 0.009. Maximal balloon pressure was significantly lower in the rotational atherectomy group (5.8 ± 1.9 atm) than in the balloon angioplasty group (7.8 ± 2.0 atm) p = 0.009.
2.1 Angiographic results.
The angiographic success rate was 92% (22 of 24 lesions) after rotational atherectomy and 100% (26 of 26 lesions) after balloon angioplasty (p = NS). Rotational atherectomy resulted in five and balloon dilation seven angiographic dissections (p = NS). There was no difference in final percent diameter stenosis: 28 ± 11% in the rotational atherectomy group versus 28 ± 14% in the balloon angioplasty group. Minimal lumen diameter was also comparable after both techniques at the end of phase 1: 2.1 ± 0.5 mm in the rotational atherectomy group versus 2.3 ± 0.6 mm in the balloon angioplasty group.
2.2 Angioscopic results.
Coronary angioscopy was tolerated well by all patients and yielded good visualization of the treated lesions. In the 50 lesions studied, coronary angioscopy detected an intimal flap in 22. Results of angioscopy in the two groups are detailed in Table 3. Flaps were visualized in 8 (33%) of 24 lesions in the rotational atherectomy group (grade 1 in 6, grade 2 in 2, grade 3 in none) compared with 14 (54%) of 26 lesions in the balloon angioplasty group (grade 1 in 4, grade 2 in 5, grade 3 in 5, p = 0.08). Seven patients developed an angioscopic longitudinal dissection (six in the balloon angioplasty group, one in the rotational atherectomy group, p = 0.05). There was no statistically significant difference in the incidence of thrombi between the two groups (four in the rotational atherectomy group vs. eight in the balloon angioplasty group, p = 0.16). Subintimal hemorrhage was observed in seven patients in the rotational atherectomy group compared with four in the balloon angioplasty group (p = 0.15). However, given the sample size, the power to detect a one-tailed significant difference between the two groups at the 5% level was 37% for the incidence of thrombi and 26% for the incidence of subintimal hemorrhage. This power was computed for a difference between the two groups corresponding to the observed differences in our data. We evaluated separately the subset of calcified lesions by angiography (n = 16 of 50) and did not find any difference in the incidence of angioscopic abnormalities according to the presence or absence of calcifications (Table 4). In the subset of calcified lesions by angiography, the angioscopic results were comparable with the two techniques. The two patients with evidence of thrombus on angiography had on angioscopy a grade 1 thrombus associated with a grade 3 flap in one patient and a grade 1 flap with no evidence of thrombus in the other. Among the 12 lesions with coronary dissection on angiography, angioscopy was normal in 1 and showed a longitudinal dissection in 2, a flap in 6 and a combination of these observations in 3.
Complications occurring during the procedure and during the hospital period were rare. No patients died, and none needed emergency bypass surgery. One patient developed a Q wave myocardial infarction 2 days after successful balloon angioplasty of the right coronary artery. Another patient required stent implantation for a nonocclusive type C dissection that developed after balloon angioplasty. Two patients in the rotational atherectomy group had target vessel occlusion within 12 h of the end of the procedure and required repeat dilation, with stent implantation in one patient. Final results were excellent in both patients.
Coronary angioscopy has been shown to be superior to angiography in detecting intraluminal changes. Several studies have documented its validity for assessment of plaque morphology in various clinical syndromes and after interventional procedures, such as balloon angioplasty [4, 5]and laser angioplasty . In a recent study evaluating the intracoronary changes that occur during the first hour after balloon angioplasty, significant progression of intimal dissection and thrombus formation could be demonstrated by angioscopy, with 61% of flaps and 8% of thrombus immediately after angioplasty reaching, respectively, 100% and 92% at 1 h. This progression of dissection and thrombus formation remained undetected at angiography.
In the present study, in addition to angiography we used angioscopic evaluation of the coronary lumen to define any potential benefit of rotational atherectomy followed by balloon angioplasty compared with standard balloon angioplasty alone. In the absence of an internationally recognized angioscopic classification, we used our own system based on our previous experience to describe flaps, thrombi, subintimal hemorrhage and longitudinal dissections. In our experience, it was at times difficult to differentiate a grade 1 thrombus from a subintimal hemorrhage into the atherosclerotic plaque. In the present study, we included only those lesions that were bulging toward the lumen, albeit minimally, as grade 1 thrombus. Using the 4.5F Baxter ImageCath angioscope, we routinely obtained good angioscopic images before and after intervention, without adverse clinical events.
There is some experimental and clinical evidence that rotational atherectomy improves the initial results of percutaneous transluminal coronary angioplasty [14–16]in complex, grade B1 or higher lesions. Vandormael et al. in the only prospective, randomized study compared rotational atherectomy, excimer laser angioplasty and balloon angioplasty in 620 patients with complex coronary lesions. The procedural success rate was higher after rotational atherectomy than after balloon angioplasty, with fewer major complications. At 6 months, the restenosis rate was comparable in the three groups. High frequency intravascular ultrasound has proved to be useful for evaluating results of various transcatheter therapies, including rotational atherectomy and balloon angioplasty . Kovach et al. showed that rotational atherectomy increases coronary artery lumen cross-sectional area in heavily calcified target lesions primarily by the removal of atherosclerotic plaque with selective ablation of calcified elements. Adjunctive balloon angioplasty further increases lumen area by a combination of vessel wall expansion and plaque dissection, with no further reduction in plaque mass.
The results of the present study are in accordance with previous experimental, clinical and ultrasound results, suggesting less plaque dissection after rotational atherectomy than after balloon angioplasty alone. We observed a statistically significant lower incidence of longitudinal dissections and a trend toward fewer intimal flaps after rotational atherectomy followed by additional balloon angioplasty than after balloon angioplasty alone. In addition, flaps were less severe: no grade 3 flaps after rotational atherectomy compared with five after balloon angioplasty alone. The difference in these angioscopic observations can most likely be explained by the different mechanisms of the two techniques used in our study. Waller described three potential mechanisms of lumen enlargement due to balloon angioplasty: 1) displacement of soft plaque elements; 2) fracture of the plaque; and 3) stretching of the normal arterial wall or the more elastic plaque elements. From histologic studies [18, 19], it has been postulated that after rotational atherectomy, the arterial lumen is smooth walled and circular. In atherosclerotic vessels treated with atherectomy , damage to the media was minor, and there were no intimal splits or medial dissections.
3.1 Limitations of the study.
We did not perform coronary angioscopy immediately after rotational atherectomy to identify morphologic changes due to rotational atherectomy alone, but only after additional balloon angioplasty. However, the present method of using a small burr (≃70% of the artery diameter), followed by systematic low pressure angioplasty, is widely accepted. We are aware that our classification system is limited because of the subjective nature of the interpretation, but it has the merit of being simple. Lesions were not imaged before intervention because we wanted to avoid the “Dotter” effect produced by the angioscope transducer itself, which might have affected the interpretation of angioscopic images. The clinical implications of our results are difficult to establish because of the relatively small number of patients and the low incidence of major complications in the two groups.
Our results show that rotational atherectomy followed by balloon angioplasty leads to fewer longitudinal dissections and a trend toward fewer intimal flaps than balloon angioplasty alone. However, our angioscopic differences did not lead to an outcome difference between the two groups. The long-term advantages of preventing flaps and dissections cannot yet be determined and warrant further study.
This study was presented in part at the 44th Annual Scientific Session of the American College of Cardiology, New Orleans, Louisiana, March 1995.
- Received May 6, 1996.
- Revision received June 11, 1997.
- Accepted June 21, 1997.
- The American College of Cardiology
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