Continued improvement of clinical outcome and cost effectiveness following intravascular ultrasound guided PCI: insights from a prospective, randomised study

OBJECTIVE

To investigate in a prospective randomised study both long term clinical effects and cost effectiveness of percutaneous coronary interventions (PCI) with or without intravascular ultrasound (IVUS) guidance.

METHODS

108 male patients with stable angina referred for PCI of a significant coronary lesion were randomly assigned to IVUS guided PCI or conventional PCI. Individual accumulated costs of the entire follow up period were calculated and compared in the randomisation groups. Effectiveness of treatment was measured by freedom from major adverse cardiac events.

RESULTS

Cost effectiveness of IVUS guided PCI that was noted at six months was maintained and even accentuated at long term follow up (median 2.5 years). The cumulated cost level was found to be lower for the IVUS guided group, with a cumulated cost of &163 672 in the IVUS guided group versus &313 706 in the coronary angiography group (p = 0.01). Throughout the study, mean cost per day was lower in the IVUS guided PCI group (&2.7 v & 5.2; p = 0.01). In the IVUS group, 78% were free from major adverse cardiac events versus 59% in the coronary angiography group (p = 0.04) with an odds ratio of 2.5 in favour of IVUS guidance.

CONCLUSION

IVUS guidance results in continued improvement of long term clinical outcome and cost effectiveness. The results of this study suggest that IVUS guidance may be used more liberally in PCI.

[Coronary atherosclerosis assessed by coronary angiography or intravascular ultrasound]

Intensive lowering of serum cholesterol in patients with ischaemic heart disease may retard atherosclerotic progression, and may even cause a limited regression in some patients and partly restore endothelial function. Coronary angiography has been the standard method to evaluate coronary anatomy. However, coronary angiography delineates only the vessel lumen as a silhouette, a perspective that is incapable of reflecting the irregular nature of the atherosclerotic vessel wall changes. Three-dimensional intravascular ultrasound provides cross-sectional and longitudinal images of both the vessel lumen and wall and the plaque volume can be measured in entire arterial segments. Three-dimensional intravascular ultrasound is a reliable technique to measure progression and regression of atherosclerosis in coronary arteries.

Reproducibility of intravascular ultrasound and intracoronary Doppler measurements

The aim of this study was to evaluate the reproducibility of intravascular ultrasound (IVUS) and intracoronary (IC) Doppler flow velocity measurements. The use of IVUS and IC Doppler has been suggested as a means for percutaneous coronary intervention (PCI) guidance in a series of studies. This would require an acceptable level of accuracy and reproducibility of these two methods for lesion evaluation. In this study, the main focus was on the issue of reproducibility. One hundred and eight patients referred for PCI entered into the study. Inter- and intraobserver variability was measured. Catheter difference was assessed. On-line and off-line measurements were compared. MUSIC criteria were assessed off-line, twice. Calculated and measured diameters were compared. After having obtained initial IC Doppler measurements, the Doppler wire was immediately withdrawn and repositioned for reacquisition of Doppler measurements. IVUS measurements are reproducible and reliable off-line and, to a slightly lesser degree, on-line. Area measurements should be performed more than once and the mean used for vessel description. Lumen diameters should be calculated from the mean of the area measurements. A measuring technique consensus should be reached and adhered to. CFR measurements can be used to determine reduced vs. normal flow reserve. In this study, it was found that proximal to distal velocity ratio and diastolic to systolic velocity ratio variability made these parameters unsuitable for PCI guidance.

Myocardial perfusion imaging and coronary angiography in patients with known or suspected stable angina pectoris

INTRODUCTION

The patho-physiological cause of angina pectoris is myocardial ischaemia, which can be objectified by myocardial perfusion imaging (MPI).

METHODOLOGY

MPI was undertaken prior to coronary angiography (CAG) in 86 randomly selected patients with known or suspected stable angina pectoris.

RESULTS

Among 78 adequately stressed patients, MPI was normal in 28 (36%) and showed reversible and irreversible perfusion abnormalities in 30 (38%) and 20 patients (26%), respectively. Coronary angiograms were normal in 28 (36%) and revealed at least one > or = 50% stenosis in 50 patients (64%) (16 with single and 34 with multi vessel disease). Using angiography as a reference, the sensitivity and specificity of MPI in detecting coronary artery disease was 88% and 93%, respectively.

DISCUSSION

MPI demonstrates regional hypoperfusion whereas CAG depicts anatomical stenosis in epicardial arteries. Both modalities are potentially relevant in patients with stable angina pectoris. The functional significance of coronary artery lesions is, however, variable and MPI can demonstrate normal myocardial perfusion in the presence of moderate lesions. MPI exhibited a high sensitivity and specificity regarding significant lesions. More than one third of the subjects had a normal MPI and a normal CAG. Patients with stable angina pectoris and a normal MPI have a very low risk of cardiac events and do usually not require further invasive investigation or therapy. Reversible ischaemia and irreversible ischaemia with demonstration of viable tissue call for coronary revascularisation.

[Myocardial scintigraphy and coronary arteriography in patients with known or suspected stable angina pectoris]

INTRODUCTION

Myocardial perfusion imaging (MPI) demonstrates regional hypoperfusion, whereas coronary angiography shows anatomical stenoses in epicardial arteries. Both modalities are potentially relevant in patients with stable angina pectoris.

MATERIALS AND METHODS

MPI was undertaken before angiography in 86 randomly selected patients with stable angina pectoris.

RESULTS

Of 78 adequately stressed patients, MPI was normal in 28 (36%) and showed reversible and irreversible perfusion abnormalities in 30 (38%) and 20 patients (26%), respectively. Coronary angiograms were normal in 28 (36%) and revealed at least one > or = 50% stenosis in 50 patients (64%) (16 with single vessel and 34 with multivessel disease). With angiography as reference, the sensitivity and specificity of MPI in the detection of coronary artery disease were 88% and 93%, respectively.

DISCUSSION

Patients with stable angina pectoris and a normal MPI have a very low risk of cardiac events and do not usually require invasive investigation and therapy. Reversible ischaemia and irreversible ischaemia with viable tissue call for coronary revascularisation.

[DANAMI. A Danish study of invasive versus conservative treatment of patients with post-infarction ischemia who had received thrombolytic therapy]

INTRODUCTION

To compare an invasive strategy employing percutaneous transluminal coronary angioplasty (PTCA) or coronary artery by-pass grafting (CABG) with a medical strategy in patients who had received thrombolytic treatment for first acute myocardial infarction (AMI), and with signs of inducible ischaemia.

METHODS

In a prospective study 1008 patients were randomized, 503 to invasive treatment, of whom 266 (52.9%) had PTCA, and 147 (29.2%) CABG, 505 to conservative treatment, of whom eight (1.6%) were revascularized within two months.

RESULTS

After a median follow-up of 2.4 years the mortality in the invasive group was 3.6% vs. 4.4% (p = 0.45) in the conservative group, re-infarction incidence was 5.6% vs. 10.5% (p = 0.0038) and percentage of admissions with unstable angina was 17.9% vs. 29.5% (p < 0.00001).

DISCUSSION

We conclude that post-infarct patients with inducible ischaemia should be referred to coronary angiography and revascularised accordingly.