Dipyridamole stress echocardiography in patients with severe left main coronary artery narrowing. Echo Persantine International Cooperative (EPIC) Study Group--Subproject "Left Main Detection"

Left main coronary artery disease: A review of the spectrum of noninvasive diagnostic modalities

Medically managed significant left main (LM) stem disease has been considered a determinant of increased cardiac mortality approaching 50% at 3-year follow-up. Despite the clinical significance of LM disease, studies comparing the various diagnostic modalities, especially noninvasive, are sparse. Clinicians, particularly imagers, should be aware of the strengths and weaknesses of existing modalities to diagnose LM disease as integrating many clues (history, symptoms, electrocardiogram, and stress hemodynamics are essential to suspect this diagnosis and proceed to the next step). Here we review the existing data on the current role of electrocardiography, nuclear myocardial perfusion imaging (single photon emission computed tomography and positron emission tomography), stress echocardiography, cardiac computed tomography, and cardiac magnetic resonance imaging in diagnostic evaluation of LM disease. Wherever applicable we have extended our discussion to multivessel coronary artery disease encompassing scenarios where LMS can present as LM equivalent with or without extensive multivessel coronary artery disease.

Angiographically borderline left main coronary artery lesions: correlation of transthoracic doppler echocardiography and intravascular ultrasound: a pilot study

Background

the clinical decision making could be difficult in patients with borderline lesions (visually assessed stenosis severity of 30 to 50%) of the left main coronary artery (LM). The aim of the study was to evaluate the relationship between transthoracic Doppler (TTDE) peak diastolic flow velocity (PDV) and intravascular ultrasound (IVUS) measurements in the assessment of angiographically borderline LM lesions.

Methods

27 patients (mean age 64 ± 8 years, 21 males) with borderline LM stenosis referred for IVUS examination were included in the study. We performed standard IVUS with minimal lumen area (MLA) and plaque burden (PB) measurement and routine quantitative coronary angiography (QCA) with diameter stenosis (%DS) and area stenosis (%AS) assessment in all. During TTDE, resting PDV was measured in the LM.

Results

interpretable Doppler signal could be obtained in 24 patients (88% feasibility); therefore these patients entered the final analysis. MLA was 7.1 ± 2.7 mm². TTDE measured PDV correlated significantly with IVUS-derived MLA (r = -0.46, p < 0.05) and plaque burden (r = 0.51, p < 0.05). Using a velocity cut-off of 112 cm/sec TTDE showed a 92% sensitivity and 62% specificity to identify IVUS-significant (MLA < 6 mm²) LM stenosis.

Conclusion

In angiographically borderline LM disease, resting PDV from transthoracic echocardiography is increased in presence of increased plaque burden by IVUS. TTDE evaluation might be a useful adjunct to other invasive and non-invasive methods in the assessment of borderline LM lesions. Further, large scale studies are needed to establish the exact cut-off value of PDV for routine clinical application.

The unresolved issues with risk stratification and management of patients with coronary artery disease undergoing major vascular surgery

PURPOSE

The purpose of this article, with a specific focus on patients undergoing vascular surgery, is to review controversial issues related to mechanisms of perioperative myocardial infarction (MI), coronary artery disease detection, and strategies to reduce perioperative complications. We propose explanations for the many conflicting results that have recently emerged in the literature.Source documents: We searched MEDLINE and reviewed all relevant manuscripts and scientific statements regarding management of patients undergoing non-cardiac surgery.

PRINCIPAL FINDINGS

Identification and prevention of ischemia in patients undergoing vascular surgery remains controversial. While the identification of preoperative ischemia is a marker of a higher perioperative risk, the value of identifying such ischemia has been questioned. We believe this may be, at least in part, due to our limited understanding of perioperative MI. Appropriate management of patients, based on the results of such testing, is likely the key to improving outcomes, and deserves further investigation. Efforts aimed at reducing the ischemic consequences of severe coronary plaques (by revascularization or beta-blocker therapy) have yielded conflicting results. The use of high doses of preoperative beta-blocker therapy may be harmful. Some studies suggest a promising role for statin therapy. Benefits of acetylsalicylic acid must be weighted against the risk of bleeding.

CONCLUSION

Many questions remain unanswered about the impact of detecting inducible ischemia, and the role of revascularization or beta-blockers in patients undergoing vascular surgery. A better understanding of the pathophysiology of perioperative MI is critical, in order to identify the best approach to improve cardiac outcomes in these patients.

Limitations of preoperative dobutamine stress echocardiography in identifying severe left main coronary artery stenosis: a report of two cases and a brief review

PURPOSE

Using case illustrations, to elucidate factors which increase the likelihood of false negative preoperative dobutamine stress echocardiography (DSE) studies in patients with severe left main coronary artery stenosis, and to provide criteria which must be met in order to ensure the accurate interpretation of these tests.

CLINICAL FEATURES AND SOURCE

Two patients presented for elective abdominal aortic aneurysm repair within a one-month period of time. Both patients had DSE as part of their preoperative assessment, which were interpreted as normal. Nevertheless, both suffered major coronary events in the perioperative period, and both proved to have severe left main coronary artery stenosis on postoperative angiography. A narrative review is presented based on a selection of the current literature, and local experience with the technique. Some pitfalls in the interpretation of these tests are presented, along with modalities to increase their sensitivity and specificity.

CONCLUSION

DSE is an important and useful modality in the preoperative cardiac evaluation of patients who are unable to exercise. However the reliable interpretation of the test depends on an understanding of the limitations of the procedure.

Comparison of ischemic response during exercise and dobutamine echocardiography in patients with left main coronary artery disease

OBJECTIVES

This study sought to compare manifestations of myocardial ischemia evoked by exercise and dobutamine echocardiography in patients with left main coronary artery disease.

BACKGROUND

During exercise testing, left ventricular cavity dilation, marked ST segment depression and blood pressure decrease indicate severe coronary artery disease. Whether these signs are comparably evoked by dobutamine echocardiography has not been described.

METHODS

Fifty-four patients who underwent stress echocardiography (36 exercise, 18 dobutamine) and coronary angiography showing > or = 50% left main stenosis were analyzed. Electrocardiographic and blood pressure changes, symptoms, wall motion score indexes and sensitivity for coronary artery disease were compared. In 47 patients, the left ventricular endocardium was traced to quantify volumes and ejection fraction.

RESULTS

Stress-induced regional wall motion abnormalities developed in 91% of patients; this was not different on exercise (89%) or dobutamine echocardiography (94%). Rate-pressure product and wall motion score index, similar at rest, tended to be higher after exercise than after dobutamine stress (p = 0.07 and p = 0.05, respectively). ST segment depression > or = 1 mm was more common with exercise (p = 0.005). Ejection fraction and end-systolic and end-diastolic volume indexes were comparable at rest in both groups. With exercise, ejection fraction decreased in 87% of patients, and end-systolic and end-diastolic volume indexes increased in 80%. In contrast, with dobutamine, decreased ejection fraction and increased volume indexes were infrequent. Ejection fraction was lower ([mean +/- SD] 45 +/- 19% vs. 54 +/- 12%, p = 0.007) and end-diastolic (69 +/- 26 vs. 50 +/- 17 ml/m2, p =0.02) and end-systolic (39 +/- 20 vs. 24 +/- 13 ml/m2, p = 0.02) volume indexes were higher after exercise than after dobutamine stress.

CONCLUSIONS

On the basis of changes in regional wall motion both dobutamine and exercise echocardiography have a comparable high sensitivity in diagnosing myocardial ischemia in left main coronary artery disease. However, conventional signs of severe myocardial ischemia, including left ventricular cavity dilation and marked ST segment depression, occur more often with exercise than with dobutamine echocardiography.

Results of dipyridamole plus atropine echo stress test for the diagnosis of coronary artery disease

Sensitivity of dipyridamole stress echocardiography (DIP-E) has been reported to be less than ideal in particular subsets of patients such as those with less severe extent of coronary artery disease (CAD). To verify if sensitivity could be improved, ATRO (1 mg in 2 minutes) was added at the end of a negative high-dose (0.84 mg/kg over 10 minutes) DIP-E in 61 consecutive patients (58 men, aged 53 +/- 7 years) evaluated for chest pain (33%) or for detection of residual ischemia after acute myocardial infarction (AMI) or previous MI (67%). DIP-E was positive in 28/61 (46%) and negative in 33/61 (54%) patients. Additional echo positivity was obtained in 18/33 (54%) patients after ATRO. Coronary arteriography was normal in 6 patients (10%); 1-vessel CAD was diagnosed in 28 (46%), 2-vessel CAD in 16 (26%) and 3-vessel CAD in 11 (18%) cases. The sensitivity for CAD diagnosis was 49% (27/55) for DIP-E and 84% (46/55) for DIP-E+ATRO (p < 0.001). Specificity was 83% and 80%, respectively. Diagnostic accuracy increased from 52% to 83% (p < 0.001). The better diagnostic accuracy of DIP-E was mainly related to the significant increase in sensitivity of the combined test in patients with 1-vessel CAD (from 46% to 75%) (p < 0.005). At quantitative coronary evaluation, compared to patients with positive DIP-E+ATRO or negative DIP-E+ATRO test, patients with positive DIP-E had a higher mean % diameter stenosis: 80 +/- 13% vs 72 +/- 24% and 65 +/- 36%, respectively. Peak heart rate was significantly higher after the addition of ATRO vs basal and DIP alone in patients with a positive DIP-E+ATRO test. The addition of ATRO to DIP increases diagnostic accuracy of DIP-E particularly in patients with less severe extent of CAD; ATRO may be considered as a useful routine procedure for increasing diagnostic value of DIP-E test.