Dipyridamole-thallium versus dobutamine echocardiographic stress testing: a clinician's viewpoint

[Preoperative stress testing in patients prior to vascular surgery]

Myocardial infarction is the leading cause of mortality during peripheral artery surgery. The review summarizes the data on cardiac event risk stratification in angiosurgical patients by preoperative stress testing. The prognostic value of positive and negative results is described. Stress testing with physical activity or pharmacological agents is rarely indicated in patients at low risk of major adverse cardiovascular events. Stress testing may be used in patients at increased risk of myocardial infarction (functional activity less than <4 metabolic equivalents), and if the test results should change the approaches to perioperative therapy, anesthesia or the volume of surgical intervention and, in rare situations, to perform coronary revascularization.

[The role of dobutamine stress echocardiography in the clinical routine of a department of cardiology]

BACKGROUND

The aim of this study was to assess the role of dobutamine stress echocardiography (SE) for diagnosis and therapy of coronary artery disease (CAD) in the routine practice of a cardiological department in which bicycle stress-testing, scintigraphy and coronary angiography are available.

METHODS

Between January 1997 and September 1998, 123 patients (79 men, 44 women, 60.1 +/- 9.9 years) underwent SE. SE-indication, SE-result and the consequence of the SE were registered. A telephone follow-up, asking for events and cardiac interventions, took place after at least one year.

RESULTS

SE was performed in 57 patients with suspected CAD and in 66 patients with known CAD. The indications were inconclusive bicycle stress-testing or perfusion scintigrams (n = 77), search for hibernation (n = 22), discrepancy between presenting symptoms and results of previous investigations (n = 14) and preoperative risk stratification (n = 10). In the group with suspected CAD, the proportion of female patients was higher (p = 0.001), in the group with known CAD the proportion of male patients was higher (p = 0.002). SE showed an ischemic reaction in 35 patients, hibernation in 24 patients, no ischemic reaction in 56 patients and was inconclusive in 8 patients. The consequence of SE was recommendation for diagnostic coronary angiography (n = 27), revascularisation (n = 10), abstention from any invasive intervention (n = 77), noncardiac surgery (n = 9) and electrophysiological investigation (n = 1). During the investigated period, 955 bicycle stress-tests, 677 Thallium scintigrams and 987 coronary angiograms were carried out. During the follow-up (15 +/- 2.9 months) 4 patients died. In 6 patients cardiac interventions were carried out. No differences were observed regarding events and interventions depending on SE results and consequences.

CONCLUSIONS

At a cardiological department SE plays a role if findings are inconclusive and if hibernation or operative risk is looked for. A negative SE result most commonly leads to abstention from invasive intervention. If the SE result is positive, the recommendation for invasive intervention is also influenced by the clinical symptoms and the size of the ischemically reacting myocardium.

Detection and management of coronary artery disease in patients with rheumatologic disorders

Coronary heart disease causes significant morbidity and mortality in our society and is more common in patients with some rheumatic disorders. A thorough history is the most essential element in assessing patients with chest pain syndrome or dyspnea who are at risk of harboring coronary artery disease. Based on the level of suspicion, a noninvasive test is commonly ordered to confirm the diagnosis. If a patient is active and can exercise, then treadmill or bike stress echocardiography is recommended. In addition to assessment of valvular, pericardial, and myocardial function at rest, stress echocardiography permits direct visualization of left ventricular cavity enlargement or wall motion abnormalities, which imply significant myocardial ischemia. If the echocardiography laboratory does not have sufficient expertise or experience with this technique, then exercise thallium is the next study of choice. If a patient is inactive or is unable to exercise, then dobutamine stress echocardiography is recommended. For patients who are in atrial fibrillation, have permanent pacemakers, who cannot augment their heart rate to a minimum of 85% MPHR, dipyridamole thallium is an acceptable alternative. An ischemic response in a symptomatic patient in most cases requires further evaluation with cardiac catheterization. Based on the patient's clinical presentation and physiologic and anatomic findings, important therapeutic decisions can then be made.

Comparative usefulness of myocardial velocity gradient in detecting ischemic myocardium by a dobutamine challenge

OBJECTIVES

We tested the hypothesis that ischemic myocardium can be sensitively detected using tissue Doppler-derived myocardial velocity gradient (MVG) by a dobutamine challenge.

BACKGROUND

Although tissue Doppler imaging (TDI) has recently emerged to quantify regional myocardial contraction, increased translational motion during a dobutamine challenge may affect the measurements. MVG is an indicator of regional myocardial contraction independent of the translational motion.

METHODS

We studied 19 patients with (n = 13) and without (n = 6) confirmed single-vessel coronary artery disease. Left ventricular short-axis tissue Doppler images were obtained along with conventional echocardiograms during a submaximal two-step dobutamine challenge (10 and 30 microg/kg body weight per min). Endocardial velocity as well as MVG were derived from TDI using computer analysis in the anteroseptal and posterior segments and were compared with visual interpretation.

RESULTS

MVG demonstrated a significant dose-responsive increase in the nonischemic segments (anteroseptal: 2.6 +/- 0.8/s to 6.0 +/- 1.0/s [mean +/- SD], p < 0.05; posterior: 3.9 +/- 0.7/s to 7.6 +/- 1.8/s, p < 0.05) but remained unchanged in the ischemic segments (anteroseptal: 2.5 +/- 0.8/s to 2.7 +/- 0.7/s, p = NS; posterior: 3.4 +/- 1.0/s to 4.1 +/- 0.9/s, p = NS). Endocardial velocity failed to clearly demonstrate the differing responses between the nonischemic (anteroseptal: -2.3 +/- 1.2 to -2.7 +/- 1.6 cm/s, p = NS; posterior: 3.8 +/- 1.1 to 73 +/- 2.7 cm/s, p < 0.05) and ischemic segments (anteroseptal: -2.1 +/- 0.5 to -2.8 +/- 0.8 cm/s, p = NS; posterior: 4.2 +/- 0.8 to 6.5 +/- 2.6 cm/s, p = NS). Wall motion abnormality was hardly detectable with visual interpretation (wall motion score range 1.00 to 1.33).

CONCLUSIONS

Abnormal segments could be sensitively detected by using MVG in a submaximal dobutamine challenge, even where conventional methods failed to detect the abnormality.