Stenting of "unprotected" left main coronary artery stenoses: early and late results

Left main coronary artery stenosis: state-of-the-art

Patients with stenosis of the left main coronary artery present difficult challenges. The risks associated with this lesion have been known since the early days of angiography when patients were found to have increased mortality during follow-up. This information led to the general guidelines that surgical revascularization should be considered the treatment of choice in patients with significant left main coronary artery stenosis. Current advances in invasive cardiology have brought important information to the field. Intravascular ultrasound is now used routinely to evaluate angiographically indeterminate lesions with criteria now set forward as to what constitutes an indication for revascularization. Stents have even further dramatically changed the landscape. There are substantial issues, however, that need to addressed. These include the following: (1) the effect of specific lesion location on outcome - it is known that patients with distal bifurcation left main disease have worse outcome; (2) the potential for subacute thrombosis of the left main coronary artery; (3) the impact of left ventricular function and patient comorbidities irrespective of the degree and location of left main coronary artery stenosis; and (4) the risk-benefit ratio of stenting versus coronary artery bypass graft surgery. These issues are currently being addressed in two seminally important trials including the SYNTAX trial, which randomizes patients with left main and/or three-vessel disease to either coronary artery bypass graft surgery or a TAXUS drug-eluting stent. This trial is in the final stages of patient recruitment and will have important implications for the field. The other trial is the COMBAT trial, which is focused exclusively on left main coronary artery stenosis and randomizes patients with left main coronary artery disease either to a Sirolimus-eluting stent (Cypher, Johnson and Johnson Cordis, USA) or to coronary artery bypass graft surgery. The field of left main coronary artery disease continues to expand in terms of the evidence available for optimal patient evaluation and selection of treatment modalities.

Complex Coronary Interventions: Unprotected Left Main and Bifurcation Lesions

Percutaneous coronary intervention has moved forward with great speed since the advent of stents and now more recently the introduction of drug-eluting technologies. This has seen the modern interventional cardiologist tackle more and more complex coronary lesions, of which unprotected left main (ULM) and bifurcations still remain challenging and controversial. ULM coronary artery stenosis traditionally remains a surgical indication although there have been recent reports and studies demonstrating the feasibility of a percutaneous strategy in select patient groups. Furthermore, drug-eluting stents have shown great benefit in reducing the problem of restenosis and have also become the mainstay treatment modality for bifurcation lesions with a choice between one- or two-stent strategies determined by the extent of disease burden in the main vessel and side branch and the response of the side branch ostium following treatment of the main vessel. This article will provide a contemporary review of percutaneous intervention for these two lesion subsets and describe the relative merits of each of the different strategies in current use with a glimpse into what the future may hold.

Rapamycin-eluting stents for the treatment of unprotected left main coronary disease

BACKGROUND

Conventional bare stents have been used to treat unprotected left main (LM) coronary artery stenosis. However, restenosis remains the main limitation. Since rapamycin-eluting stents (RES) appear to inhibit neointimal proliferation, their application to this specific site seems promising.

METHODS

Since May 2002, we have studied a series of 52 patients with LM lesions treated with RES. Forty-seven patients presented with de novo stenoses, and 5 had in-stent restenosis; 19 patients required combined stent treatment for other remote lesions in the coronary tree, 6 of them at the level of proximal right coronary artery. The RES was implanted directly at the LM in 39 patients; 13 others needed predilation. Once deployed, the RES was overexpanded with short balloons adjusted to the LM length in 44 patients. Quantitative coronary angiograms were analyzed in the same view before and immediately after treatment and at follow-up. Patients were followed-up closely and new cardiac catheterization was scheduled at 6-month evaluation or earlier in the presence of symptoms. At follow-up study, quantitative coronary angiography and motorized intravascular ultrasound analyses were performed in 35 (67%) patients.

RESULTS

Primary success was obtained in 50 patients (96%). Two patients (4%) developed a non-Q-wave myocardial infarction. All patients were symptom-free at discharge. After a mean follow-up of 12 +/- 4 months, 50 patients (96%) remain asymptomatic. No late death or acute thrombosis have been recorded. Two patients became symptomatic 2 and 4 months after treatment, respectively. One had restenosis at a remote site, while the other had in-segment restenosis. None of the remaining 33 angiographically evaluated patients developed restenosis at any site. Target lesion revascularization was 1/52 (2%).

CONCLUSIONS

Although longer-term follow-up studies are needed, the tailored treatment of coronary lesions located at the LM by overexpanded RES is feasible and safe. Midterm results seem promising, which might help to shift the orientation of patient management from surgical to percutaneous revascularization.

Long term follow up after elective percutaneous coronary intervention for unprotected non-bifurcational left main stenosis: is it time to change the guidelines?

BACKGROUND

According to the American College of Cardiology/American Heart Association guidelines, percutaneous coronary intervention (PCI) for left main coronary artery (LMCA) stenosis is contraindicated and coronary artery bypass graft surgery (CABG) is preferred. However, PCI of the LMCA is performed under exceptional circumstances.

OBJECTIVE

To analyse the data of patients who underwent PCI of the unprotected LMCA in St Antonius Hospital, Nieuwegein, Netherlands.

RESULTS

In a database of 17 683 PCI procedures, 71 patients (0.4%) were found with non-bifurcational LMCA stenosis who underwent an elective PCI between 1991 and 2001. Ages ranged from 26.7-86.5 years. Severe concomitant disease was the most frequent argument in favour of PCI instead of CABG. PCI consisted of only balloon angioplasty in 23 cases (32.4%). A stent was used in 46 cases (64.4%). Average follow up was 43 months (range 0-121 months). One patient died one day after the procedure. The total one year survival rate was 98.6% (70/71). Seven patients died during the follow up period, mostly because of non-cardiac reasons. The annual mortality rate was 2.5%. Recurrent elective percutaneous transluminal coronary angioplasty for restenosis of the LMCA was performed in one patient (1.4%) six weeks after the initial procedure. CABG was required in 13 patients (18.3%) throughout the follow up period.

CONCLUSION

These results suggest that at highly experienced centres, elective PCI of the non-bifurcational LMCA can be performed safely where the anatomy is suitable.

Short- and long-term results of emergency and elective percutaneous interventions on left main coronary artery stenoses

In this prospective study, we analyzed the short- and long-term outcomes of percutaneous interventions on significant left main coronary artery (LM) stenoses. Between January 1998 and June 2000, 18 patients underwent emergency interventions on unprotected LM stenoses (group 1), while 15 patients had elective interventions on protected LM stenoses (group 2). Despite a procedural success of 88.9% in group 1, event-free in-hospital and mortality rates were 50.0% and 38.9%. After 6.4 +/- 4.4 months of follow-up, late event-free survival and mortality rates were 33.3% and 38.9%. In group 2, procedural success was 100%, with 100% event-free in-hospital survival; late event-free survival and mortality rates were 93.3% and 0% after 6.7 +/- 4.1 months of follow-up. Emergency interventions on LM stenoses remain a procedure with high acute and mid-term mortality. In spite of the high rate of major adverse cardiac events, an acceptable long-term survival can be achieved.

Long-term clinical outcomes after unprotected left main trunk percutaneous revascularization in 279 patients

BACKGROUND

Percutaneous coronary revascularization (PCI) has been increasingly applied to unprotected left main trunk (LMT) lesions, with varied long-term success. This study attempts to define the predictors of outcome in this population.

METHODS AND RESULTS

Two hundred seventy-nine consecutive patients who had LMT PCI at 1 of 25 sites between 1993 and 1998 were studied. Forty-six percent of these patients were deemed inoperable or at high surgical risk. Thirty-eight patients (13.7%) died in hospital, and the rest were followed up for a mean of 19 months. The 1-year incidence was 24.2% for all-cause mortality, 20.2% for cardiac mortality, 9.8% for myocardial infarction, and 9.4% for CABG. Independent correlates of all-cause mortality were left ventricular ejection fraction </=30%, mitral regurgitation grade 3 or 4, presentation with myocardial infarction and shock, creatinine >/=2.0 mg/dL, and severe lesion calcification. For the 32% of patients <65 years old with left ventricular ejection fraction >30% and without shock, the prevalence of these adverse risk factors was low. No periprocedural deaths were observed in this low-risk subset, and the 1-year mortality was only 3.4%.

CONCLUSIONS

Patients undergoing unprotected LMT PCI have frequent serious comorbidities and consequently have high event rates. PCI may be an alternative to CABG for a select proportion of elective patients and may also be appropriate for highly symptomatic inoperable patients. Meticulous follow-up of hospital survivors is required because of the rather high mortality during the first few months after treatment.

Elective stenting of unprotected left main coronary artery stenosis: effect of debulking before stenting and intravascular ultrasound guidance

OBJECTIVES

We sought to evaluate: 1) the long-term outcomes of 127 selected patients receiving unprotected left main coronary artery (LMCA) stenting; and 2) the impact of the debulking procedure before stenting and intravascular ultrasound (IVUS) guidance on their clinical outcomes.

BACKGROUND

The long-term safety of stenting of unprotected LMCA stenoses has not been established yet.

METHODS

A total of 127 consecutive patients with unprotected LMCA stenosis and normal left ventricular function were treated by elective stenting. The long-term outcomes were evaluated between two groups: IVUS guidance (n = 77) vs. angiographic guidance (n = 50); and debulking plus stenting (debulking/stenting; n = 40) vs. stenting only (n = 87).

RESULTS

Angiographic restenosis was documented in 19 (19%) of 100 patients. The lumen diameter after stenting was significantly larger in IVUS-guided group (p = 0.003). The angiographic restenosis rate was significantly lower in the debulking/stenting group (8.3% vs. 25%, p = 0.034). The reference artery size was the only independent predictor of angiographic restenosis. During follow-up (25.5 +/- 16.7 months), there were four deaths, but no nonfatal myocardial infarctions occurred. The survival rate was 97.0 +/- 1.7% at two years.

CONCLUSIONS

These data suggest that stenting of unprotected LMCA stenosis might be associated with a favorable long-term outcome in selected patients. Guidance with IVUS may optimize the immediate results, and debulking before stenting seems to be effective in reducing the restenosis rate. However, we need a large-scale, randomized study.

Ostial left anterior descending coronary artery stent positioning: partial preinflation prevents stent oscillation and facilitates accurate deployment

Ostial intracoronary stent deployment is complicated by the influence of cardiac motion, which causes the stent to oscillate back and forth during the cardiac cycle. Accurate deployment can be facilitated by initial low pressure inflation of the balloon on which the stent is mounted. This stabilizes the stent within the stenosis, while still allowing adjustment of the exact stent location prior to deployment.

Coronary angioplasty performed using the FullFlow mechanical dilatation-perfusion catheter: initial animal experience

We report our initial experience with an animal model, using a new mechanical catheter-based dilatation system, the FullFlow (FF) catheter. The primary purpose of this study was to compare coronary flow achieved using the FF perfusion catheter and a traditional balloon angioplasty perfusion catheter. Baseline average peak velocity (APV) measurements were obtained using the FloWire Doppler guide wire. Either a Surpass Perfusion balloon (PB) or an FF catheter was advanced to a coronary segment. Doppler measurements were made before, during, and after full device expansion. Simultaneous heart rate, EKG, and blood pressure readings were recorded. Significant 36.1% and 29% reductions in mean APV were found for PB when comparing baseline to device-up measurements and when comparing device-down to device-up measurements, respectively. In contrast, significant 12.2% and 18.5% increases were seen in mean APV for the FF. No significant differences were found in heart rate, systolic blood pressure, diastolic blood pressure, or ST-segment changes. The FF system produces superior downstream coronary perfusion with side-branch coronary patency compared with results using a contemporary perfusion balloon angioplasty catheter.

Unprotected left main coronary artery stenting: immediate and medium-term outcomes of 140 elective procedures

OBJECTIVES

We sought to evaluate immediate and late outcomes after stenting for left main coronary artery (LMCA) stenosis.

BACKGROUND

Conventional percutaneous transluminal coronary angioplasty (PTCA), for which coronary artery bypass grafting (CABG) has been the gold standard therapy for years, has yielded poor results in unprotected LMCA lesions. The development of coronary stents, together with their dramatic patency improvement provided by new antiplatelet regimens and their validation against restenosis, warrants a reappraisal of angioplasty in LMCA stenosis.

METHODS

From January 1993 to September 1998, 140 consecutive unselected patients with unprotected LMCA stenosis underwent elective stenting. Group I included 47 high-CABG-risk patients, and group II included 93 low-CABG-risk patients. Ticlopidine without aspirin was routinely started at least 72 h before the procedure and continued for one month. Patients were reevaluated monthly. A follow-up angiography was requested after six months.

RESULTS

The procedure success rate was 100%. One-month mortality was 9% (4/47) in group I and 0% in group II. A follow-up angiography was obtained in 82% of cases, and target lesion revascularization was required in 17.4%. One-year actuarial survival was 89% in the first 29 group I patients and 97.5% in the first 63 group II patients.

CONCLUSIONS

Stenting of unprotected LMCA stenosis provided excellent immediate results, particularly in good CABG candidates. Medium-term results were good, with a restenosis rate of 23%, similar to that seen after stenting at other coronary sites. Stenting deserves to be considered a safe and effective alternative to CABG in institutions performing large numbers of PTCAs.