The effects of successful PTCA on left ventricular function: assessment by exercise echocardiography

Improvement of left ventricular function after percutaneous coronary intervention in patients with stable coronary artery disease and preserved ejection fraction: Impact of diabetes mellitus

Background

Many patients with stable coronary artery disease (CAD) have no visual segmental wall motion abnormalities and a left ventricular (LV) ejection fraction (LVEF) ≥ 50% at rest despite significant coronary artery stenosis. Here, the aim was to determine the impact of percutaneous coronary intervention (PCI) on LV function assessed by enhanced echocardiography in patients with stable CAD with or without diabetes mellitus type 2 and a preserved LVEF.

Methods

Sixty-six consecutive patients with CAD and LVEF ≥ 50%, admitted to the hospital for planned coronary angiography, were prospectively assessed. PCI was performed for coronary artery stenosis > 70%. CAD extent was assessed using SYNTAX and EXTENT scores. To assess LV function, LVEF, global longitudinal strain (GLS), and LV peak systolic myocardial velocity (S′) were measured and Tei index was calculated before and 3 months after PCI.

Results

Before PCI, LVEF, GLS, and Tei index were significantly worse in diabetic patients. LV functional indices improved significantly after PCI in all patients (p < 0.001). Multivariate linear regression analyses were performed to evaluate the impact of selected factors on LV function after PCI expressed as changes (Δ) of LVEF, GLS, S′, and Tei index. LV function improvement expressed as ΔGLS was associated only with SYNTAX score. Higher SYNTAX scores were related to greater GLS improvement (β = 0.003, 95% confidence interval: 0.0004–0.005; p = 0.02).

Conclusions

Percutaneous coronary intervention significantly improved LV function in diabetic and non-diabetic CAD patients with preserved LVEF. Enhanced echocardiography allowed an assessment of subtle changes in LV function.

Usefulness of stress echocardiography for risk stratification of patients after percutaneous coronary intervention

The prognostic value of stress echocardiography in patients with previous percutaneous coronary intervention (PCI) remains undefined. The aim of this study was to investigate the prognostic implication of stress echocardiography after PCI. The study group comprised 1,063 patients (794 men, 65 +/- 10 years of age) who underwent stress echocardiography with exercise (n = 105), dipyridamole (n = 780), or dobutamine (n = 178) after a median of 10 months from a successful PCI. Of these patients, 616 (58%) complained of chest pain and 447 (42%) were asymptomatic. Stress echocardiogram was positive for inducible ischemia in 328 patients (31%). During a median follow-up of 20 months, there were 167 events (61 deaths, 106 infarctions). Independent predictors of mortality were age (hazard ratio [HR] 1.06, 95% confidence interval [CI] 1.03 to 1.09, p <0.0001), wall motion score index at rest (HR 3.91, 95% CI 2.19 to 6.99, p <0.0001), and ischemia at stress echocardiography (HR 1.82, 95% CI 1.05 to 3.16, p = 0.03). Five-year mortalities were 20% in patients with and 9% in those without ischemia (p = 0.006). Independent predictors of hard events were ischemia at stress echocardiography (HR 3.82, 95% CI 2.75 to 5.29, p <0.0001), age (HR 1.02, 95% CI 1.01 to 1.04, p = 0.009), wall motion score index at rest (HR 1.98, 95% CI 1.30 to 3.02, p = 0.002), multivessel disease at time of PCI (HR 1.45, 95% CI 1.05 to 2.02, p = 0.02), and female gender (HR 1.44, 95% CI 1.03 to 2.01, p = 0.03). Five-year hard event rates were 53% in patients with and 16% in those without ischemia (p <0.0001). Stress echocardiographic positivity added prognostic information to clinical and at-rest echocardiographic parameters in symptomatic and asymptomatic patients. Moreover, it identified a subset of patients at higher risk of developing hard events independent of the subtending coronary anatomy (multivessel or single vessel disease). In conclusion, stress echocardiography is effective in risk-stratifying patients with previous PCI. In particular, inducible ischemia is a strong and independent predictor of mortality and hard events.

Stress echocardiography: technical considerations

Stress echocardiography has evolved into a widely practiced and accepted method for the noninvasive assessment of the status of the coronary anatomy. Furthermore, this modality incorporates the ability to assess left ventricular function, valvular structure and function, intracardiac masses, the pericardium, and hemodynamics. The extent to which this tool can reliably provide useful clinical information is dependent, in part, on optimal performance. The purpose of this report is to provide an overview of those technical considerations that can contribute to the successful operation of a stress echocardiography laboratory. Consideration is given to personnel qualifications, functional requirements of the digital acquisition/storage/replay system, functional integration of the various hardware components, characteristics of the software, physical layout of the facility, and alternatives to treadmill exercise as the stressor. A thorough understanding of the physiologic basis of stress echocardiography, coupled with optimization of resources used in its performance, enable this tool to be an extraordinarily useful and cost-efficient method for comprehensive cardiovascular assessment.

[Diagnostic efficacy of myocardial tomographic imaging in the detection of restenosis after coronary angioplasty]

INTRODUCTION AND OBJECTIVES

To analyze the efficacy of single photon emission tomography (SPET) with 99mTc-compounds for the diagnosis of restenosis of previous percutaneous transluminal coronary angioplasty (PTCA).

PATIENTS AND METHODS

Seventy-one patients (16 women, median age: 60 years, 35 with multivessel disease, 78 arteries with PTCA) with previous PTCA and with coronary angiography performed after scintigraphy were studied. 99mTc-SPET exercise (53 with MIBI and 18 with tetrofosmin) was performed, for clinical reasons, to all patients between one month and 4 years after PTCA. Intravenous dipyridamole was administered simultaneously to 16 patients who had insufficient exercise.

RESULTS

SPET sensitivity, specificity, positive predictive values, negative predictive values and global values were all significantly higher than those obtained with exercise tests (80% vs 63%; p = 0.05; 83% vs 37%; p = 0.001; 91% vs 69%; p = 0.007; 64% vs 31%; p = 0.009, and 81% vs 55%; p = 0.0006, respectively). These results were significantly superior in patients with one vessel disease than in patients with multivessel disease.

CONCLUSIONS

SPET exercise with 99mTc-compounds is a test with a high efficacy for the diagnosis of post-PTCA restenosis, mainly in patients with one vessel disease.

Use of stress testing to evaluate patients with recurrent chest pain after percutaneous coronary revascularization

Controversy exists regarding the diagnostic accuracy, optimal technique, and timing of noninvasive stress testing after percutaneous transluminal coronary angioplasty (PTCA). Many patients return with chest pain after PTCA, and because the incidence of restenosis has been reported to be as high as 50%, a noninvasive test with a high predictive value is needed to reduce the need for unnecessary coronary angiography. Studies have shown that the sensitivity and specificity of stress testing varies depending on the amount of time elapsed since the procedure. Soon after a successful PTCA, perfusion defects on nuclear imaging following exercise or pharmacologic stress may be detected in asymptomatic patients without angiographic restenosis. In many patients, abnormal stress myocardial perfusion scans will normalize spontaneously, and thus stress testing with nuclear imaging within 4 to 6 weeks of PTCA lacks specificity for detecting restenosis. In contrast, stress echocardiography which detects wall motion abnormalities rather than perfusion mismatch has been reported to offer more specific information on myocardial ischemia and restenosis early after PTCA. In patients who develop chest pain more than 6 weeks after PTCA, the ability to accurately identify restenosis is shared by both echocardiographic and nuclear imaging methods. The purpose of this review is to clarify the strengths, pitfalls, and prognostic value of different stress modalities and cardiac imaging techniques in patients who develop chest pain within 6 months of undergoing PTCA.

Clinical and prognostic usefulness of supine bicycle exercise echocardiography in the functional evaluation of patients undergoing elective percutaneous transluminal coronary angioplasty

BACKGROUND

Supine bicycle exercise echocardiography (SBEE) has never been used before and early after percutaneous transluminal coronary angioplasty (PTCA) for assessing the functional outcome of the procedure and predicting late restenosis.

METHODS AND RESULTS

We selected 76 subjects with stable angina, normal wall motion at rest, and exercise-induced wall-motion abnormalities before PTCA. SBEE with peak exercise imaging and the use of a 16-segment, four-grade score model was performed 54 +/- 15 hours after PTCA. No exercise-related adverse events occurred. Patients were grouped according to SBEE results: group 1 (n = 35, 46%) with negative exercise ECG and echo; group 2 (n = 19, 25%) with a positive exercise ECG but normal echo; and group 3 (n = 22, 29%) with a positive exercise echo with either a positive (n = 7, 32%) or negative (n = 15, 68%) ECG. Exercise performance significantly improved in all groups. In group 3, peak wall-motion score index decreased from 1.27 +/- 0.11 before to 1.15 +/- 0.06 after PTCA (P < .05), and duration of wall-motion abnormalities went from 81 +/- 24 to 47 +/- 19 seconds (P < .05). The rate of clinical restenosis (ie, angina recurrence or positive 6-month SBEE in asymptomatic patients, both associated with angiographic restenosis > 50%) was 37%. By multiple logistic regression analysis, clinical restenosis was associated with a positive post-PTCA exercise echo (odds ratio [OR] 3.08, 95% confidence interval [CI] 1.66 to 5.72; P = .0004) and with increasing values of pre-PTCA wall-motion score index (OR 2.86, 95% CI 1.92 to 4.27; P = .005) and duration of wall-motion abnormalities (OR 2.12, 95% CI 1.07 to 4.20; P = .04).

CONCLUSIONS

SBEE is a safe and reliable tool to demonstrate changes in exercise-induced wall-motion abnormalities after PTCA and provides prognostic information in the risk assessment of clinical restenosis.

Use of exercise echocardiography to evaluate patients after coronary angioplasty

Exercise echocardiography is a sensitive, specific, and highly accurate method for detecting coronary restenosis and progressive compromise of untreated arterial segments in patients who have undergone percutaneous transluminal coronary angioplasty. It is far more reliable in predicting the status of the coronary anatomy in such patients than exercise electrocardiography or symptomatic status.

Stress echocardiography. Part I. Exercise echocardiography: techniques, implementation, clinical applications, and correlations

OBJECTIVE

To describe the techniques and applications of exercise echocardiography.

DESIGN

We review pertinent experimental and clinical studies from the literature and present our experience with the first 2,000 patients who underwent exercise echocardiography in our laboratory.

MATERIAL AND METHODS

The indications for and contraindications to exercise echocardiography and the advantages, limitations, and accuracy of this procedure in comparison with other techniques for detecting coronary artery disease are discussed.

RESULTS

Exercise echocardiography is increasingly used for the noninvasive evaluation of coronary artery disease because, in addition to its diagnostic capabilities, it offers attractive features such as portability, versatility, rapid availability of results, and relatively low cost. For accurate interpretation of the results, the workload achieved and the time between completion of exercise and image acquisition must be considered. The major limitation of exercise echocardiography is the high degree of operator dependence. For accurate interpretation of regional wall motion abnormalities and recognition of ischemic changes, specific training and extensive experience are necessary.

CONCLUSION

Although exercise echocardiography has only relatively recently become a widely used technique, it has proved to have considerable accuracy in the diagnosis of coronary artery disease (mean sensitivity, 84%; mean specificity, 87%). In high-volume laboratories, feasibility studies have shown success rates between 90 and 99%; thus far, reproducibility has been satisfactory. Other applications of exercise echocardiography being studied are follow-up monitoring after revascularization, determination of prognosis, and assessment of valvular heart disease.

The role of noninvasive cardiac imaging in the evaluation of the postcoronary intervention patient

Noninvasive diagnostic techniques are playing an increasingly prominent role in the evaluation of the postcoronary interventional patient. Radionuclide myocardial perfusion imaging has proved to be of value in assessing procedural success in patients with suboptimal angiographic results and/or multivessel coronary artery disease. However, in asymptomatic patients with single vessel disease, the use of myocardial perfusion imaging may not be cost-effective for follow-up after successful coronary intervention. The timing of these studies is important when used to predict coronary restenosis. Radionuclide ventriculography and echocardiography are two imaging modalities that, in conjunction with exercise stress, can be used to predict patient outcome and clinical events postcoronary intervention. A high degree of operator expertise is required for the optimal interpretation of the echocardiographic studies.

Rapid resolution of hyperkinesis after exercise. Two-dimensional echocardiographic studies in normal subjects

Abnormal wall motion detected with exercise echocardiography identifies ischemic myocardium, while normal myocardium exhibits hyperkinetic motion. The normal, hyperkinetic response to exercise is transient and is predictive of an excellent prognosis. However, there are few data on the duration of the hyperkinesis after peak exercise. Our purpose was to determine the time course of wall thickening after exercise in eight normal subjects with two-dimensional echocardiography. Percentage of wall thickening increased from 53 +/- 24 percent at baseline to 82 +/- 24 percent at 0 to 2 min postexercise (p < 0.001 vs baseline) and then decreased to 64 +/- 27 percent at 2 to 4 min, and 54 +/- 20 percent at 5 to 7 min (both NS vs baseline). We conclude that (1) systolic wall thickening is maximal within the initial 2 min following peak exercise, and (2) accurate identification of hyperkinetic, normal myocardium with exercise echocardiography requires immediate postexercise imaging.

Exercise echocardiography

Exercise echocardiography is a versatile, noninvasive diagnostic test that involves the recording and interpretation of 2-dimensional echocardiograms prior to, during, and after exercise. By analyzing and comparing wall motion at each stage, a prediction about the presence or absence of coronary artery disease can be made. The development of a wall motion abnormality is both sensitive and specific for the presence of a significant coronary stenosis. Changes in regional systolic function during exercise enable the clinician to distinguish between infarction and ischemia. Thus, the test yields information on the presence, extent, severity, and location of coronary artery disease. Echocardiography can be adapted to almost any form of stress, although treadmill or bicycle exercise are most commonly employed. An advantage of bicycle stress echocardiography is the opportunity to image during exercise, rather than relying on postexercise recording. This contributes to enhanced sensitivity, although false-positive results may increase due to the difficulties of analyzing wall motion during strenuous exercise. Exercise echocardiography increases the diagnostic accuracy of stress testing in a manner similar to radionuclide perfusion imaging. It is particularly useful in the setting of an ambiguous stress electrocardiography (ECG) or when a false-negative or false-positive result is suspected. It has been successfully applied to patients following revascularization and yields useful prognostic data in a variety of clinical situations. Exercise echocardiography is being increasingly utilized as a safe and accurate test in patients with known or suspected coronary artery disease.

Dobutamine stress echocardiography before and after coronary angioplasty

Myocardial function was assessed by stress echocardiography in 28 patients before and after successful elective coronary angioplasty. Dobutamine stress echocardiography was performed using up to 40 micrograms/kg/min, followed by the addition of atropine in 20 patients to achieve 85% of the predicted maximal exercise heart rate. The initial studies were performed 1 day before and the second ones within 3 days (mean 1.3) after angioplasty. Peak heart rates and systolic blood pressures were the same for the 2 studies. The frequency of dobutamine-induced new wall motion abnormalities decreased from 20 (71%) before to 4 (14%) after angioplasty (p less than 0.0001). Before angioplasty, wall motion score index (an indicator of left ventricular wall motion, an increase in which indicates impaired wall motion due to myocardial ischemia) increased from 1.06 at rest to 1.23 at peak stress (p less than 10(-6)), but there was no significant increase in this index in the study after angioplasty. Before angioplasty, 14 patients (50%) developed chest pain during the stress test compared with 6 (21%) after angioplasty (p = 0.05), and before angioplasty, the stress test was stopped before the target heart rate was achieved, because of symptoms, ST-segment change or severe new wall motion abnormality in 14 patients compared with 7 after angioplasty (p = 0.09). Thus, early after angioplasty there is a reduction in myocardial ischemia as assessed by dobutamine stress echocardiography.

Stress echocardiography versus radionuclide stress techniques

The different modalities of stress echocardiography and stress thallium-201 imaging have comparable sensitivity, specificity, and overall predictive accuracy in the diagnosis and prognosis of coronary artery disease. They are also comparable in the assessment and follow-up of patients treated with thrombolytic therapy or who have undergone percutaneous transluminal coronary angioplasty and coronary artery bypass graft surgery. Stress radionuclide ventriculography has a lower sensitivity and specificity as compared to stress echocardiography and stress thallium. Dipyridamole thallium has a higher sensitivity as compared to dipyridamole echocardiography in the diagnosis and prognosis of coronary artery disease. New techniques such as dobutamine echocardiography, adenosine stress thallium-201, and adenosine echocardiography have individually shown high sensitivities, specificities, and accuracy. However, further studies are needed on their comparative value. The major advantages of stress echocardiography over radionuclide stress techniques are: lack of radiation exposure; less expense; less time consumption; less personnel required; and greater availability. Its major disadvantage, however, is the inability to obtain adequate studies in all patients.

Dipyridamole echocardiography

Intravenous dipyridamole is a potent coronary vasodilator that has been extensively investigated over the past several years in the noninvasive assessment of patients with suspected coronary artery disease when exercise cannot be performed or is suboptimal. As an alternative to exercise studies, dipyridamole has been used in combination with different cardiac imaging techniques such as echocardiography, thallium scintigraphy, and radionuclide ventriculography. Extensive experience has been obtained with dipyridamole thallium-201 imaging for coronary artery disease screening, risk stratification, and prognosis after an acute coronary event. However, experience with the use of dipyridamole in combination with two-dimensional echocardiography has been limited. Dipyridamole increases coronary blood flow in nondiseased coronary vessels relative to coronary vessels with significant luminal narrowings. These provide the basis for detecting regional differences in flow by using different cardiac imaging techniques. Two-dimensional echocardiography would show regional wall-motion abnormalities in response to those regional differences in coronary blood flow. In this article, the most commonly used protocols, safety, and practicability of dipyridamole echocardiography are reviewed. As an alternative to exercise, dipyridamole echocardiography shares all the indications of a standard exercise test. Clinical applications of dipyridamole echocardiography include coronary artery disease screening, suspected coronary artery spasm, postmyocardial infarction risk stratification, evaluation of percutaneous transluminal coronary angioplasty results, and prognosis following an acute coronary event. Compared to conventional (ECG) exercise testing, dipyridamole echocardiography appears to be equally sensitive but more specific. Compared to atrial pacing, dipyridamole provokes ischemia at a lower rate pressure product and results in a greater ST segment depression suggesting that dipyridamole induces more profound myocardial ischemia than atrial pacing. Dipyridamole thallium and exercise thallium have shown to be equally sensitive and specific in the assessment of coronary artery disease. High dose dipyridamole echocardiography appeared to be equally sensitive and more specific. Experimental studies have demonstrated that dobutamine appears to be a more powerful pharmacological agent in inducing wall-motion abnormalities. Dipyridamole echocardiography as compared to stress echocardiography offers the advantage of obtaining better quality postintervention images. With regard to sensitivity and for coronary artery disease diagnosis, both techniques appear to render similar results. Although further studies are needed, the available data indicates that cardiac ultrasound imaging prior to and following the intravenous administration of dipyridamole may be an attractive alternative to thallium perfusion imaging in the clinical setting, particularly when radionuclide capabilities are not present.

Quantitative stress echocardiography

Dramatic improvements in our ability to treat coronary artery disease have created the need to develop sensitive and specific noninvasive tests for diagnosing and assessing the severity of ischemic disease. The purpose of this review is to examine stress echocardiography and, in particular, quantitative stress echocardiography in this context. Methodology and technical aspects of performing and interpreting stress echocardiography are discussed, including the type of exercise performed, imaging and recording techniques, and methods for on-line and off-line analysis. Qualitative, semiquantitative, and quantitative approaches are compared and contrasted. In assessing quantitative stress echocardiography, the role of global measurements of left ventricular function including ejection fraction, peak systolic pressure to end-systolic volume index ratio, as well as regional measurements including wall-motion analysis and wall stress, are discussed. Pertinent literature using quantitative approaches is reviewed including those comparing quantitative stress echocardiography with other noninvasive modalities. Future directions for study are also addressed. We concluded that quantitative stress echocardiography has excellent sensitivity and specificity for diagnosing ischemic heart disease. It was useful in localizing lesions, defining multivessel disease, and predicting patients with poor prognosis postmyocardial infarction. Its reproducibility makes it a valuable technique in following patients noninvasively over time.

Clinical efficacy of PTCA and identification of restenosis: evaluation by serial body surface potential mapping

We used serial body surface potential mapping (BSPM) with the departure map technique to evaluate the clinical efficacy of percutaneous transluminal coronary angioplasty (PTCA) in various pathophysiologic stages of coronary artery disease, and to detect restenosis. The BSPM was performed prior to, 1 week after, and 1 month after PTCA. A follow-up coronary angiography was performed 3 to 6 months after PTCA, and BSPM was also performed at the same time. The results of BSPM were compared with those of thallium-201 single-photon emission computed tomography (Tl-201 SPECT) and radionuclide ventriculography. After PTCA, BSPM showed a significant reduction in the departure area, the Tl-201 SPECT also showed a significant reduction in the extent and severity scores, and the left ventricular ejection fraction improved significantly. In the cases with restenosis, the departure area, which had decreased in size after PTCA, showed an increase in size. After successful re-PTCA, the size of the departure area again became smaller. We concluded that BSPM, which is a simple, noninvasive, and inexpensive method, is useful in the evaluation of the clinical efficacy of PTCA and in the detection of restenosis after successful PTCA.

Evidence of hibernating myocardium by a new transesophageal echocardiographic technique

Reversal of resting wall motion abnormalities after successful coronary angioplasty were documented in a patient with the use of a novel approach to stress testing. Transesophageal stress echocardiography utilizes transesophageal atrial pacing to provoke myocardial ischemia while the left ventricular contractility is being monitored by means of transesophageal echocardiography. The potential use of this technique is illustrated in this report.