Detection of restenosis with dobutamine stress test after coronary angioplasty

Exercise stress testing, myocardial perfusion imaging and stress echocardiography for detecting restenosis after successful percutaneous transluminal coronary angioplasty: a review of performance

When chest symptoms recur in a patient who underwent percutaneous transluminal coronary angioplasty (PTCA), it is necessary to rule out restenosis (R). Three main noninvasive tests suggest the presence of R: exercise stress test (XT), myocardial perfusion imaging (MPI) and stress echocardiography (s-echo). The objectives of this review were: (1) to estimate the pretest probability of R as a function of time after PTCA in symptomatic patients and (2) to obtain an approximation of the diagnostic parameters of the XT, MPI and s-echo for detecting R. A MEDLINE search (English-language, years: 1980-2001) was conducted to identify studies examining post-PTCA functional testing for diagnosing R. Data from the studies were pooled. Comparing studies was often difficult due to varying methodology in the studies. Pretest probability of R in symptomatic patients increases in a nonlinear fashion from 20% or less at 1 month, to nearly 90% at 1-year postangioplasty. The approximated accuracy of the XT, MPI, and s-echo for detecting R was 62, 82 and 84%, respectively. During the first month after PTCA, none of the noninvasive modalities is able to accurately detect R. Late (7-9 months) after PTCA, the pretest probability of R is high and therefore the noninvasive measure may be spared. Our analysis suggests that MPI and s-echo should be preferred over the XT for diagnosing R.

Minimally invasive evaluation of coronary stents with electron beam computed tomography: In vivo and in vitro experience

We sought to describe the value of electron beam computed tomography (EBCT) to detect stent restenoses at follow-up and to identify characteristic EBCT features of coronary stents. Six coronary stents (GRII, Jostent, NIR, PS, Micro, Wiktor) were scanned in vitro (10 1. 5-mm-thick slices, 15-cm FoV, 100-ms AT) before and after inflation with 3.0-, 3.5-, and 4.0-mm balloons to study intensity values and different stent dimensions in comparison to caliper measurements. In 44 patients (60 +/- 10 years, 4 females) we prospectively compared EBCT findings [eight 8-mm-thick slices in the flow mode, 26-cm field of view (FoV), 50 ms acquisition time (AT)] with 6-month angiographic outcome after placement of 86 stents in 49 vessels. For the detection of significant angiographic luminal narrowing (>/=75%) that occurred in 17/49 vessels (35%), we found a sensitivity of 65%, a specificity of 84%, and a positive and negative predictive value of 69% and 82%, respectively. The in vitro data show significant differences in image intensity between the stents and a significant gradual decrease in image intensity with increasing stent diameters. The mean differences between EBCT and caliper measurements for the length and diameter were 0.17 +/- 0.18 mm and -0.32 +/- 0.25mm, respectively. EBCT is currently the only noninvasive technique that allows the assessment of stent dimensions and stent geometry, which may prove useful in patients when intravascular ultrasound cannot be performed. Contrast-enhanced EBCT is a promising tool for minimally invasive stent patency evaluation at follow-up, especially in patients that are unable to exercise. Cathet. Cardiovasc. Intervent. 48:39-47, 1999.

Reliability of the exercise-induced ST-segment changes to detect restenosis three months after coronary angioplasty: significance of the appearance in other leads

BACKGROUND

Exercise-induced ST-segment changes 3 months after angioplasty may sometimes show a false-positive result.

METHODS

We therefore analyzed the ST changes observed during the exercise tests performed before and 3 months after angioplasty in 118 patients with single-vessel coronary artery disease.

RESULTS

Ninety-two (78%) of the 118 patients had ST changes in the same lead before and after angioplasty, whereas the remaining 26 (22%) patients had ST changes in other leads in the postangioplasty test when compared with the preangioplasty exercise test. Restenosis was found in 44 (48%) of the 92 patients with ST changes in the some lead but in only four (15%) of the 26 patients with ST changes in other leads.

CONCLUSIONS

Exercise-induced ST-segment changes are not reliable markers of restenosis 3 months after angioplasty. ST-segment changes observed in other leads after angioplasty compared with the preangioplasty exercise test may show a false-positive result.

Reliability of exercise-induced ST segment changes to detect restenosis 3 months after coronary angioplasty: significance of the appearance in other leads

Exercise-induced ST-segment changes 3 months after angioplasty sometimes may show a false-positive result. We therefore analyzed the ST changes observed during the exercise tests performed before and 3 months after angioplasty in 118 patients with single-vessel coronary artery disease. Ninety-two (78%) of the 118 patients had ST changes in the same lead before and after angioplasty, whereas the remaining 26 (22%) patients had ST changes in other leads in the postangioplasty exercise test when compared with the preangioplasty test. Restenosis was found in 44 (48%) of the 92 patients with ST changes in the same lead but in only 4 (15%) of the 26 patients with ST changes in other leads. We conclude that exercise-induced ST segment changes are not reliable markers of restenosis 3 months after angioplasty. ST segment changes observed in other leads after angioplasty may show a false-positive result when compared with the preangioplasty exercise test.

Detection of high-grade restenosis after PTCA using contrast-enhanced electron beam CT

BACKGROUND

Contrast-enhanced electron beam computed tomography (EBCT) has been shown to permit noninvasive visualization of the coronary arteries. We determined the value of EBCT to noninvasively detect high-grade restenosis after percutaneous transluminal coronary angioplasty (PTCA).

METHODS AND RESULTS

Fifty patients (37 to 68 years of age), were investigated by EBCT at a mean interval of 9 months after PTCA of coronary artery stenoses. Forty axial cross-sections of the heart (3-mm slice thickness, 1-mm overlap) were acquired triggered to the ECG after intravenous injection of contrast agent. Three-dimensional reconstructions of the coronary arteries were rendered with a lower threshold of 80 HU to selectively visualize the contrast-enhanced vessel lumen. EBCT results were compared with conventional quantitative coronary angiography (QCA) performed within 1 week. In 6 patients, the PTCA segment could not be evaluated because of impaired image quality. Sixteen of the remaining 44 patients had high-grade restenoses in QCA (>70% diameter reduction), which was correctly detected by EBCT in 15 cases (94% sensitivity). There were 5 false-positive EBCT results of high-grade restenosis (82% specificity).

CONCLUSIONS

EBCT with intravenous injection of contrast agent permits the noninvasive diagnosis of restenosis after PTCA, with high sensitivity and sufficient specificity.

Detection of patients with restenosis after PTCA by dipyridamole-atropine-stress-echocardiography

Stress-echocardiography (SE) has been proven to be a valuable method for the diagnosis of coronary artery disease. For patients who cannot exercise, pharmacological stress-echocardiography represents an alternative method for the induction of cardiovascular stress. Few studies exist concerning the value of dipyridamole-SE for the detection of restenosis in patients after primary successful PTCA. It has been demonstrated that the addition of atropine can significantly increase the diagnostic potential of dipyridamole-SE, especially in patients with 1- or 2-vessel disease. The purpose of our study was to investigate the diagnostic value of high-dose dipyridamole-SE plus atropine (DASE) for the detection of restenosis after primary successful PTCA. We investigated 65 patients 3-6 months after PTCA before a control angiography was performed. Restenosis was defined as > 70% lumen narrowing, determined by quantitative coronary angiography. In 20/27 patients with restenosis, the DASE was pathological (sensitivity 74%); in 34/38 patients without restenosis the DASE was normal or showed no induced WMA (specificity 89%). Patients with tight restenosis (> 90%) were always correctly detected by DASE. Concerning the different vessels, restenosis of the LAD was correctly predicted by DASE in 11/12 patients, restenosis of the LCX in 6/9 patients and restenosis of the RCA in 8/11 patients. From the results of our study we conclude that DASE is a reliable diagnostic method for the non-invasive evaluation of patients after PTCA. DASE can identify patients with relevant restenosis after PTCA and help to select those patients who will probably benefit from further coronary interventions, for repeat angiography.

Radionuclide studies in patients with stress-induced ST-segment elevation after acute myocardial infarction

The meaning of a stress-induced ST-segment elevation (delta ST) after acute myocardial infarction is still controversial. Some studies show it is related to asynergy, and other studies show it is related to ischemia. However, no study has compared the delta ST with both stress-induced ischemia and stress-induced asynergy in the same group of patients. With this purpose, 88 patients were studied 16 +/- 4 days after acute myocardial infarction. They were submitted to a dobutamine stress test on two different occasions 1 to 2 days apart. Dobutamine was infused up to 40 micrograms/kg/min with blood pressure and electrocardiographic controls. Thallium-201 single-photon emission computed tomography was performed during the highest dobutamine dose and 3 to 4 hours later. Equilibrium radionuclide ventriculography was performed at rest and during the highest dobutamine dose. Global and regional (hypokinetic area) ejection fractions were quantified. The ST segment was elevated > or = 1 mm in 33 patients at rest and in 71 during stress. A stress-induced delta ST was seen in 66 patients. Redistribution was detected in 65 patients. Multiple regression analysis showed a significant correlation between ST elevation and thallium defect score both at rest and during stress. No correlation was found between delta ST and redistribution score. However, a significant inverse linear correlation was found between the delta ST and the change in regional ejection fraction: the greater the delta ST, the smaller the change in regional ejection fraction with dobutamine. In conclusion, a stress-induced delta ST is not related to ischemia but to stress-induced left ventricular asynergy.

The dobutamine stress test with thallium-201 single-photon emission computed tomography and radionuclide angiography: postinfarction study

OBJECTIVES

The purpose of this study was to investigate left ventricular wall motion changes during dobutamine-induced myocardial ischemia.

BACKGROUND

Dobutamine is increasingly used as a stress test. It has been assumed that high doses of the drug induce the same changes in contractility as physical exercise. However, some data suggest that ischemic myocardium can respond to dobutamine with an increase in contractility.

METHODS

Sixty-three postinfarction patients twice underwent the dobutamine test (up to 40 micrograms/kg per min) within 1 to 2 days. Thallium-201 single-photon emission computed tomography (SPECT) and gated equilibrium radionuclide ventriculography were performed on each patient at rest and with dobutamine. Both global and regional ejection fractions were quantified. Sixty patients underwent coronary cineangiography within 1 week. The presence of redistribution was correlated with global and regional ejection fraction changes and with coronary lesions.

RESULTS

Redistribution was present in 45 patients, and no change or a decrease in global or regional ejection fraction was detected in 22. In the entire group of patients global ejection fraction increased from 46 +/- 12% to 56 +/- 14%. The six patients with triple-vessel disease had a flat (-0.2 +/- 5%) ejection fraction response to dobutamine, whereas the remaining patients had an increase of 11 +/- 7% (p = 0.003). The regional ejection fraction of the hypokinetic area increased from 27 +/- 10% to 41 +/- 19%, showing no change or a decrease in 13 patients. The 44 patients with peri-infarct redistribution had a significantly higher increase in regional ejection fraction than those without redistribution (16.4 +/- 10% vs. 4.7 +/- 17%, p = 0.003). In the patients with peri-infarct redistribution, an inverse linear correlation was found between redistribution score and dobutamine-induced regional ejection fraction change (r = -0.44, p = 0.004).

CONCLUSIONS

Mild to moderate dobutamine-induced peri-infarct ischemia is compatible with an increase in contractility, whereas severe ischemia induces worsening of wall motion.