Long-Term Follow-Up of a High Risk Cohort After Stent Implantation in Saphenous Vein Grafts

AbstractObjectives. We sought to provide short- and long-term clinical outcomes of a high risk cohort treated with stents in saphenous vein grafts (SVGs).Background. Data on the long-term outcome of SVG stenting in high risk patients are limited.Methods. Johnson & Johnson stents were implanted in the SVGs of 186 patients (302 stents, 244 lesions). Ninety percent of patients presented with myocardial infarction (MI) or unstable angina (mean ±SD ejection fraction [EF] 44 ± 11%, patient age 71 ± 9 years, graft age 9.4 ± 5 years). Using a risk score classification, 155 patients (83%) were defined as high risk for repeat surgical repair or angioplasty.Results. The procedural success rate was 97.3%, with 2.7% major complications (death, Q wave MI, coronary artery bypass graft surgery [CABG]). Clinical follow-up was obtained in 177 patients (mean 19.1 ± 13.5 months, range 7 to 59). Event rates were 10% for death; 9% for MI; 11% for repeat CABG; and 15% for repeat angioplasty (total events 45%). Kaplan-Meier estimated survival and event-free survival at 4 years were 0.79 ± 0.06 and 0.29 ± 0.07, respectively. Predictors of death were congestive heart failure (p < 0.01) and EF <44% (p < 0.05). Predictors of combined events of death, MI and CABG were low EF (p < 0.01) and high SVG age (>10 years, p < 0.01). There were 66 revascularization procedures (35% of patients), 24% of which were in nontarget lesions. Fifty-three percent of the cardiac events occurred during the first year of follow-up. Of the 160 survivors, 36% were free of angina, 49% were in Canadian Cardiovascular Society functional class I or II, and 15% were in class III or IV. Sixty-nine percent of patients were in class I or II according to the Specific Activity Scale, and 31% of patients were in class III or IV.Conclusions. Balloon-expandable stent implantation in the SVGs of high risk patients is associated with a low early complication rate. Expected survival rates are good, as are the anginal and functional classifications, but there is a high rate of recurrent events and need for repeat revascularization. Vein graft stenting is an acceptable palliative option in many high risk patients

967-21 Long Term Results of Balloon Expandable Slotted-Tube Nitinol Stents in Canine Coronary Arteries

This study evaluated delivery performance, quantitative angiographic parameters, intravascular ultrasound appearance. long term patency and vascular histology of radio-opaque, slotted-tube nickel titanium (nitinoll stents permanently implanted in canine coronary arteries. Dogs were treated with aspirin for 1 month. Follow-up angiography and histology were performed at 0.5, 1, 3, and 6 months (number of vessels = 2, 4, 6, and 26, respectively).ResultsThirty-eight of 39 (97%) stents were successfully implanted in the mid LAD and LCX of 20 dogs. One stent, which was undersized, was successfully removed by thermal recovery. Tandem stents were placed in 2 dogs without difficulty. Intravascular ultrasound of 6 stents showed symmetrical expansion with good wall contact. Acute angiographic parameters:nominal stent size (mm)ANOVA p3.03.54.0number42212–inflation pressure (atm)5.5±056.1±1.45.9±1.60.47minimal diameter (mm)2.93±0.073.24±0.143.48±0.160.0003balloon to artery ratio1.23±0.031.25±0.101.25±0.080.65stent to artery ratio1.09±0.031.14±0.091.13±0.070.30percent recoil11.0±1.88.4±1.89.9±1.80.05At follow-up, all vessels and 9 of 9 stented sidebranches were patent. The mean percent stenosis at 3 to 6 months was –1.6±5.2 and the late loss was 0.2±0.3 mm. All struts were covered with neointima at 2 weeks. At 6 months the maximal neointimal thickness was 260±50 μm and was located adjacent to the struts. No thrombi and only occasional areas of granulation tissue with rare inflammatory cells were seen.ConclusionsA slotted tube nitinol stent has delivery performance characteristics and recoil similar to stainless steel slotted-tube stents. Nitinol stents endothelialize rapidly and intimal proliferation is insufficient to create a stenosis in this animal model. These data suggest that a slotted-tube, balloon expandable nitinol stent is sufficiently reliable and biocompatible to warrant clinical trials

Temporary Arterial Stenting: Comparison to Permanent Stenting and Conventional Balloon Injury in a Rabbit Carotid Artery Model

The objective was to assess the arterial wall response to temporary stenting with a removable nitinol stent in comparison with permanent stenting and balloon injury at 28 days in the rabbit carotid artery. Restenosis remains an important limiting factor after the implantation of permanent metallic stents and balloon angioplasty. We have developed a temporary nitinol stent that uses a bolus injection of warmed saline to collapse the stent for percutaneous removal. Vascular changes related to the thermal saline bolus injection required to remove a nitinol implanted stent were assessed in 12 rabbit carotid arteries at 7 and 28 days postinjection. Nitinol stents, inflated to 3.0 mm diameter, were implanted for 3 days (n 5 6) and histology and quantitative histomorphometry examined at 28 days. Results were compared with permanently implanted stents (n 5 5) and balloon injury (n 5 9). Dual bolus injection of 10 ml at 70°C created an acute necrotizing injury and chronic neointimal proliferation, whereas injections of 5 ml at 63°C were minimally injurious. Temporary stenting resulted in the least neointimal proliferation measured by the intima to media ratio (0.22 6 0.10 vs. 1.59 6 0.31 for permanent stenting and; 0.49 6 0.14 for balloon injury; P F 0.001). Temporary stenting maintained a significantly larger lumen than balloon (1.53 6 0.72 mm 2 vs. 0.64 6 0.14 mm 2 ; P F 0.001), which could not be explained by absolute changes in intimal cross sectional area (0.14 6 0.07 mm 2 vs. 0.21 6 0.06 mm 2 respectively; P 5 0.33). Temporary stenting resulted in a relatively larger vessel area within the external elastic lamina than with balloon (2.28 6 1.06 mm 2 vs. 1.30 6 0.18 mm 2 ; P 5 0.007). The thermal stent recovery process can create necrotizing vascular injury and neointimal proliferation at higher temperatures and injectate volumes. Stent removal after 3 days using 63°C saline bolus injection results in less neointimal proliferation than with permanent stents or balloon injury. In comparison to balloon injury, temporary stenting also may have a long-lasting beneficial effect on vessel recoil and remodeling, resulting in larger lumen size after stent removal. Cathet. Cardiovasc. Diagn. 41:85-92, 1997. r 1997 Wiley-Liss, Inc

Monitoring of heart failure: comparison of left atrial pressure with intrathoracic impedance and natriuretic peptide measurements in an experimental model of ovine heart failure

Monitoring of HF (heart failure) with intracardiac pressure, intrathoracic impedance and/or natriuretic peptide levels has been advocated. We aimed to investigate possible differences in the response patterns of each of these monitoring modalities during HF decompensation that may have an impact on the potential for early therapeutic intervention. Six sheep were implanted with a LAP (left atrial pressure) sensor and a CRT-D (cardiac resynchronization therapy defibrillator) capable of monitoring impedance along six lead configuration vectors. An estimate of ALAP (LAP from admittance) was determined by linear regression. HF was induced by rapid ventricular pacing at 180 and 220 bpm (beats/min) for a week each, followed by a third week with daily pacing suspensions for increasing durations (1–5 h). Incremental pacing induced progressively severe HF reflected in increases in LAP (5.9 ± 0.4 to 24.5 ± 1.6 mmHg) and plasma atrial (20 ± 3 to 197 ± 36 pmol/l) and B-type natriuretic peptide (3.7 ± 0.7 to 32.7 ± 5.4 pmol/l) (all P<0.001) levels. All impedance vectors decreased in proportion to HF severity (all P<0.001), with the LVring (left ventricular)-case vector correlating best with LAP (r2=0.63, P<0.001). Natriuretic peptides closely paralleled rapid acute changes in LAP during alterations in pacing (P<0.001), whereas impedance changes were delayed relative to LAP. ALAP exhibited good agreement with LAP. In summary, impedance measured with an LV lead correlates significantly with changes in LAP, but exhibits a delayed response to acute alterations. Natriuretic peptides respond rapidly to acute LAP changes. Direct LAP, impedance and natriuretic peptide measurements all show promise as early indicators of worsening HF. ALAP provides an estimate of LAP that may be clinically useful