The "slow coronary flow" phenomenon: evidence of preserved coronary flow reserve despite increased resting microvascular resistances.

INTRODUCTION: The expression "slow coronary flow phenomenon" (SCFP) indicates a slow progression of the contrast seen at the coronary angiography in the absence of epicardial stenosis and/or of other conditions associated with decreased coronary flow velocity. While microvascular abnormalities are suspected to underlie the mechanism of SCFP, they have never been directly demonstrated. METHODS AND RESULTS: Fifteen anginal patients with a positive stress test and no evidence of epicardial lesions (obstructive coronary artery disease, coronary ectasia, or coronary spasm) were enrolled. In eight patients, the diagnosis of SCFP was made (TIMI frame count>average +2SD). All subjects underwent measurement of the coronary flow reserve (CFR) and the index of microvascular resistance (IMR) using an intracoronary thermodilution method (RADI medical systems). There was no difference between groups in age, cardiovascular risk factors, blood pressure and heart rate, coronary artery diameter and fractional flow reserve (an index of the presence of epicardial stenosis). At rest, microvascular resistances (mean transit timexdistal pressure) were significantly higher in the SCFP group (SCFP: 104+/-31 versus 53+/-27, P<0.01). Showing normal responsiveness to vasodilators, this difference was abolished after induction of hyperemia (SCFP group: 34+/-22; control: 22+/-15, P=ns); coronary flow reserve was normal in the subjects with the SCFP (3.6+/-1.6). CONCLUSIONS: We provide the first human in vivo evidence that resting microvascular resistances are increased in patients with the SCFP. At the same time, showing an intact capacity to vasodilate, microvascular resistances were normal during hyperemia, and coronary flow reserve was not impaired in SCFP patients.

Non-Q-wave myocardial infarction associated with three-vessel thrombosis.

Acute coronary syndromes have been traditionally considered the consequence of the rupture of a single plaque. Recent evidence has suggested that this is not the case, and intravascular ultrasound studies have demonstrated that an average of two to three ruptured plaques are present in patients admitted to hospital for unstable angina or infarction. We present a case of three-vessel occlusive thrombosis causing non-Q-wave myocardial infarction treated successfully with IIb-IIIa inhibitors.

Symptomatic failure after sirolimus-eluting stent implantation: a rare but challenging condition.

BACKGROUND: Limited information is available regarding restenosis after implantation of a sirolimus-eluting stent (SES). OBJECTIVE: To report on angiographic characteristics, clinical presentation and treatment of this particularly complex type of coronary lesion. METHODS AND RESULTS: A total of 1424 SES were implanted in 1159 patients (average 1.2 per patient) for chronic or acute coronary syndromes in the University Hospital of Siena (Siena, Italy), which is a tertiary centre. Symptomatic in-SES restenosis was observed in 26 patients (2.2%) at 10+/-5 months (median eight months, range four to 23 months) following the initial intervention. In-SES restenosis was associated with stable angina in 16 patients, acute myocardial infarction in three patients and unstable angina in seven patients. Two patients had restenosis in two separate SES. Conditions often associated with in-SES restenosis included treatment of chronic total occlusion, geographic miss or in-stent restenosis during the index procedure. Among the first 20 patients, those with focal, in-body SES (type Ic) restenosis received balloon-only angioplasty, and patients with other patterns received repeat SES implantation. Clinical and angiographic follow-up (average 16+/-7 months) recorded one death (noncardiac) in the balloon-only group and four cases of unstable angina (three due to relapsing in-SES restenosis in the balloon-only group and the fourth due to a de novo lesion). Follow-up quantitative angiography showed a higher incidence of binary restenosis after balloon-only treatment (57% versus 17%; P<0.05), as well as higher lumen loss and loss index (P<0.05). CONCLUSIONS: Restenosis after SES implantation occurs more commonly in a focal pattern in-body or at the proximal edge of the stent. Repeat SES implantation appears to be a safer and more effective therapeutic choice than balloon-only angioplasty.

Effectiveness and safety of sirolimus stent implantation for coronary in-stent restenosis: the TRUE (Tuscany Registry of Sirolimus for Unselected In-Stent Restenosis) Registry.

OBJECTIVES: This study sought to evaluate the effectiveness and safety of the sirolimus-eluting stent in the treatment of in-stent restenosis (ISR) in consecutive unselected patients undergoing coronary intervention in a real-world scenario. BACKGROUND: Restenosis after bare metal stenting is characterized by a high rate of re-restenosis once treated with repeated percutaneous coronary intervention. METHODS: The study was designed as a prospective two-center registry. We enrolled 244 patients with ISR in a native coronary artery or saphenous vein graft who had clinical indication for repeat intervention. RESULTS: Sirolimus stent implantation was successful in all lesions. At 9-month follow-up, death occurred in 4 (1.6%) patients, myocardial infarction in 4 (1.6%), and ischemia-driven target lesion revascularization (TLR) in 12 (4.9%), for a cumulative event-free survival of 227 (93%). Although 9-month follow-up angiography was planned in all patients, only 150 (62%) patients completed it, and restenosis was present in 13 (8.7%) patients. Diabetes and non-ST-segment elevation acute coronary syndrome at presentation were the only independent predictors of freedom from ischemia-driven TLR and major adverse cardiac events. CONCLUSIONS: Sirolimus stent implantation for the treatment of ISR is effective and safe. In diabetic patients and in those with acute coronary syndrome, the higher rate of recurrence requires further evaluation.

Outcome of percutaneous hybrid coronary revascularization: bare metal stents jeopardize the benefit of sirolimus-eluting stents in the real world.

BACKGROUND: In an effort to contain procedural costs while limiting the risk of in-stent restenosis, hybrid percutaneous revascularization (ie, stenting with at least one sirolimus-eluting stent [SES] and at least one bare metal stent [BMS] in the same patient) is felt to be a cost-effective alternative to exclusive SES use. OBJECTIVE: To describe the outcome of hybrid percutaneous revascularization for the treatment of patients with multiple coronary artery lesions. METHODS AND RESULTS: Fifty-six patients (42 men; mean age [+/- SEM] 64+/-2) underwent hybrid stenting (average of 1.2 SES/patient and 1.3 BMS/patient). SES were used to treat lesions at higher restenotic potential, including longer lesions, smaller target vessels and bifurcation lesions (mean stent length [+/- SEM] was 21.1+/-1.2 mm for SES and 16.0+/-0.6 mm for BMS; stent diameter mean [+/- SEM] was 2.9+/-0.0 mm for SES and 3.1+/-0.1 mm for BMS; bifurcation lesions were 43% for SES and 7% for BMS; all P<0.01). At nine months of clinical follow-up, no death or myocardial infarction was reported. Twenty-one patients underwent clinically driven repeat coronary angiography at a mean (+/- SEM) of 8+/-1 of months (range two to 12 months) follow-up. Target lesion revascularization procedures were recorded in six patients (11%) for nine lesions (6%). Of these lesions, seven were categorized after blinded analysis as due to in-BMS restenosis and two to in-SES restenosis (P=0.01); three patients (5.4%) underwent reangioplasty for de novo lesions. There was one case of acute in-SES thrombosis. SES showed significantly less neointimal hyperplasia (late lumen loss was 0.4+/-0.1 mm for SES and 1.3+/-0.1 mm for BMS; loss index was 0.15+/-0.05 for SES and 0.48+/-0.05 for BMS; all P<0.001). CONCLUSIONS: The use of SES resulted in less neointimal hyperplasia even when used to treat lesions at higher risk for restenosis based on angiographic characteristics. BMS implantation significantly limits this beneficial effect, compromising the outcome of hybrid percutaneous coronary revascularization.