Three-dimensional echocardiographic measurement of left ventricular wall thickness: In vitro and in vivo validation

INTRODUCTION

Three-dimensional (3D) echocardiography has been shown to accurately measure left ventricular (LV) volume and mass. This study evaluated the accuracy of 3D echocardiography and the CenterSurface method for measuring LV wall thickness in vitro and in vivo.

METHOD

Three-dimensional echocardiography scans, obtained from 7 LV phantoms and subjects having healthy (n = 5) or diseased (n = 8) hearts, were digitized. Endocardial and epicardial borders were outlined and used in 3D LV reconstruction. In vitro wall thickness was compared with true micrometer measurements. Three-dimensional in vivo wall thickness was compared with 2-dimensional (2D) thickness measured by the centerline method.

RESULTS

The in vitro 3D echocardiography measurements agreed closely with true wall thickness (P <.0001), as did in vivo measurements (P <.0001).

CONCLUSION

Three-dimensional echocardiography reconstruction has previously been shown to provide accurate representation of LV shape in addition to volume and mass. This study demonstrates that the CenterSurface method provides accurate quantification of wall thickness.

Stent placement compared with balloon angioplasty for small coronary arteries: in-hospital and 6-month clinical and angiographic results

BACKGROUND

Stenting has been demonstrated to be superior to balloon angioplasty in de novo focal lesions located in large native vessels. However, in small vessels, the benefit of stenting remains questionable.

METHODS AND RESULTS

A total of 381 symptomatic patients with de novo focal lesion located on a small coronary segment vessel (<3 mm) were randomly assigned to either stent implantation (192 patients; 197 lesions) or standard balloon angioplasty (189 patients; 198 lesions). The primary end point was the angiographic restenosis rate at 6 months, as determined by quantitative coronary angiography. On intention-to-treat analysis, angiographic success rate and major adverse cardiac events were comparable: 97.9% and 4.6% versus 93.9% and 5.8% in the stent group and the balloon group, respectively. After the procedure, a larger acute gain was achieved with stent placement (1.35+/-0.45 versus 0.94+/-0.47 mm, P=0.0001), resulting in a larger minimal lumen diameter (2.06+/-0.42 versus 1.70+/-0.46 mm, P=0.0001). At follow-up (obtained in 91% of patients), angiographic restenosis rate was 21% in the stent group versus 47% in the balloon group (P=0.0001), a risk reduction of 55%. Repeat target lesion revascularization was less frequent in the stent group (13% versus 25%, P=0.0006).

CONCLUSIONS

Elective stent placement in small coronary arteries with focal de novo lesions is safe and associated with a marked reduction in restenosis rate and subsequent target lesion revascularization rate at 6 months.

Comparison of direct coronary stenting with and without balloon predilatation in patients with stable angina pectoris. BET (Benefit Evaluation of Direct Coronary Stenting) Study Group

The purpose of this study was to compare the effects of stent placement with and without balloon predilatation on duration of the procedure, reduction of procedure-related costs, and clinical outcomes. Although preliminary trials of direct coronary stenting have demonstrated promising results, the lack of randomized studies with long-term follow-up has limited the critical evaluation of the role of direct stenting in the treatment of obstructive coronary artery disease. Between January and September 1999, 338 patients were randomly assigned to either direct stent implantation (DS+; 173 patients) or standard stent implantation with balloon predilatation (DS-; 165 patients). Baseline clinical and angiographic characteristics were similar in the 2 groups. Procedural success was achieved in 98.3% of patients assigned to DS+ and 97.5% of patients assigned to DS- (p = NS), with a crossover rate of 13.9%. Compared with DS-, DS+ conferred a dramatic reduction in procedure-related cost ($956.4 +/- $352.2 vs $1,164.6 +/- $383.9, p <0.0001) and duration of the procedure (424.2 +/- 412.1 vs 634.5 +/- 390.1 seconds, p < 0.0001). At 6-month follow-up, the incidence of major adverse cardiac events including death, angina pectoris, myocardial infarction, congestive heart failure, repeat angioplasty, or coronary artery bypass graft surgery was 5.3% in DS+ and 11.4% in DS- (p = NS). Multivariate analysis demonstrated that major adverse cardiac events rates were related to stent length of 10 mm (relative risk [RR] 3.25, 95% confidence intervals [CI] 1.36 to 7.78; p = 0.008), stent diameter of 3 mm (RR 2.69, 95% CI 1.03 to 7.06; p = 0.043), and complex lesion type C (RR 2.83, 95% CI 1.02 to 7.85; p = 0.045). Thus, in selected patients, this prospective randomized study shows the feasibility of DS+ with reduction in procedural cost and length, and without an increase in in-hospital clinical events and major adverse cardiac events at 6-month follow-up.

A comparison of systematic stenting and conventional balloon angioplasty during primary percutaneous transluminal coronary angioplasty for acute myocardial infarction. STENTIM-2 Investigators

OBJECTIVES

In a multicenter, randomized trial, systematic stenting using the Wiktor stent was compared to conventional balloon angioplasty with provisional stenting for the treatment of acute myocardial infarction (AMI).

BACKGROUND

Primary angioplasty in AMI is limited by in-hospital recurrent ischemia and a high restenosis rate.

METHODS

A total of 211 patients with AMI <12 h from symptom onset, with an occluded native coronary artery, were randomly assigned to systematic stenting (n = 101) or balloon angioplasty (n = 110). The primary end point was the binary six-month restenosis rate determined by core laboratory quantitative angiographic analysis.

RESULTS

Angiographic success (Thrombolysis in Myocardial Infarction [TIMI] flow grade 3 and residual diameter stenosis <50%) was achieved in 86% of the patients in the stent group and in 82.7% of those in the balloon angioplasty group (p = 0.5). Compared with the 3% cross-over in the stent group, cross-over to stenting was required in 36.4% of patients in the balloon angioplasty group (p = 0.0001). Six-month binary restenosis (> or = 50% residual stenosis) rates were 25.3% in the stent group and 39.6% in the balloon angioplasty group (p = 0.04). At six months, the event-free survival rates were 81.2% in the stent group and 72.7% in the balloon angioplasty group (p = 0.14), and the repeat revascularization rates were 16.8% and 26.4%, respectively (p = 0.1). At one year, the event-free survival rates were 80.2% in the stent group and 71.8% in the balloon angioplasty group (p = 0.16), and the repeat revascularization rates were 17.8% and 28.2%, respectively (p = 0.1).

CONCLUSIONS

In the setting of primary angioplasty for AMI, as compared with a strategy of conventional balloon angioplasty, systematic stenting using the Wiktor stent results in lower rates of angiographic restenosis.

Comparable uptake of thallium-201 and technetium-99m MIBI in hibernating and "maimed" myocardium

Thallium-201 and technetium-99m-MIBI uptake are comparable in "maimed" (i.e., partially viable) and hibernating myocardium. The appreciation of myocardial viability should be based not only on the presence of a regional contractility improvement, but also on the evaluation of the initial level of contractility and of tracer uptake in the concerned area.

[Identification of hibernating myocardium using 99m sestamibi tomoscintigraphy at rest]

The aim of this study was to assess the value of resting 99m Tc-Sestamibi scintigraphy for the detection of hibernating myocardium in zones of contractile dysfunction. Based on a series of 25 patients, 27 segments of supposedly hibernating myocardium were identified. All these segments corresponded to left ventricular wall motion abnormalities confirmed by contrast angiography and were perfused by a stenosed coronary artery: none of these zones were infarcted. Before revascularisation, comparison of the results of ventriculography and scintigraphy showed a correlation (p < 0.001) between the severity of regional contractile dysfunction appreciated by the center line method and the degree of myocardial hypofixation of 99m Tc MIBI. Three months after revascularisation, improvement of regional wall motion, assessed by control contrast angiography, was observed in 21 of the 27 segments studied (78%). Of these 21 segments, the viability of which was confirmed, 13 had a non-transmural uptake defect and 8 were normal on pre-revascularisation scintigraphy. The 6 segments without improvement at the 3 month control, had a transmural uptake defect on scintigraphy in 67% of cases. The authors concluded that when a residual uptake defect of 99m Tc sestamibi is present, viable myocardium may also be present.

Rest technetium 99m-sestamibi tomoscintigraphy in hibernating myocardium

The myocardial uptake of rest-injected technetium 99m sestamibi on single-photon-emission computed tomographic images was assessed in 25 patients. All had an area of myocardial dysfunction that could be related to a coronary artery stenosis. None of the patients had clinical evidence of a myocardial infarction. Three months after revascularization, viability was demonstrated by contrast angiography and center-line analysis in 21 (78%) of the 27 formerly hibernating territories. Among these, none had a transmural defect, and 38% had a normal technetium 99m-sestamibi uptake. The four transmural preoperative defects were located in territories without viability. Eight of the 9 territories that were normal at scintigraphy proved to be viable postoperatively. It is concluded that as long as some residual technetium 99m-sestamibi uptake is present, viable myocardium is also present.

Reinjection as an alternative to rest imaging for detection of exercise-induced ischemia with thallium-201 emission tomography

Exercise thallium-201 single photon emission computed tomography images were compared prospectively with 4-hour redistribution images, with 4-hour reinjection images, and with images obtained at rest on a separate day in 37 patients with documented coronary artery disease. Exercise images were abnormal in 35 patients (95%). On the basis of an improvement in thallium-201 distribution between exercise and nonexercise images, overall sensitivity for the detection of coronary artery stenosis was significantly higher with reinjection at 4 hours (p < 0.05) or with a rest injection on a separate day (p < 0.05) than with redistribution imaging (84%, 83%, and 70%, respectively). Reinjection and rest injection were positive more frequently in patients with a wall-motion abnormality (76% and 80%, respectively, vs 64% at redistribution; p < 0.05 for both) or with > 90% stenosis (77% and 76%, respectively, vs 58% at redistribution; p < 0.05 for both). Among the 11 patients who had no evidence of redistribution at 4 hours, five (45%) demonstrated ischemia with reinjection and five demonstrated ischemia in the separate rest study; a total of seven patients showed improvement either at reinjection or rest. Among these 86% had a wall-motion abnormality associated with stenosis of > 90%, whereas in the other 30 patients these two conditions were observed concomitantly in only 43%. This study demonstrates that the thallium-201 4-hour postexercise reinjection technique is as sensitive as the 2-day rest/exercise method for the detection of coronary artery stenosis and provides additional information when a severe stenosis is associated with a wall-motion abnormality.

[Silent ischemic heart diseases in patients with peripheral arterial diseases. Screening and 5-year prognosis in a population of 418 patients]

Silent ischaemic heart disease was looked for by exercise stress testing in 418 patients with chronic obliterative arterial disease of the lower limbs with no clinical or electrocardiographic signs of myocardial ischaemia. In the initial work-up, 6.2% of patients had a positive exercise test and the results were suspect in 9.2% of patients. These patients were followed up for 5 years. There were 42 deaths (10%). The cause of death was cardiovascular in 53.7% of cases (myocardial infarction 40.4%) and malignant disease in 35.7%. During the 5 year follow-up, ischaemic heart disease present as angina pectoris or myocardial infarction in 115 cases (27.5%). Patients who had a positive exercise stress test initially had a particularly high death rate (23%) and developed clinical signs of coronary insufficiency in 57.5% of cases. On the other hand, the peripheral vascular complications were relatively rare in this series: cerebrovascular accidents: 1.4%; retinal vascular accident: 1.1%; carotid surgery: 1.6%; lower limb amputation: 1.9%; lower limb vascular surgery: 17.7%. Silent ischaemic heart disease is very prevalent in patients with obliterative arterial disease of the lower limbs and is a main vital prognostic factor in these patients. These results confirm the need for a complete cardiovascular check-up in all patients with peripheral arterial disease.