Incidence and correlates of complex ventricular arrhythmias during dobutamine stress echocardiography after acute myocardial infarction

Ventricular Fibrillation in Late Recovery After Dobutamine Stress Echocardiography

A 62-year-old man with multiple cardiac risk factors, including diabetes mellitus type II, treated hypertension, and hyperlipidemia, had a dobutamine stress echocardiogram performed as part of a preoperative evaluation. At peak stress the patient developed an apical regional wall motion abnormality. Approximately 12 minutes into the recovery period, the patient developed ventricular tachycardia that degenerated into ventricular fibrillation. He was successfully resuscitated and underwent emergency coronary angiography that showed a 95% distal left anterior descending coronary artery stenosis.

Prognostic significance of nonsustained ventricular tachycardia during dobutamine stress echocardiography

Nonsustained ventricular tachycardia (NSVT) is a well-recognized side effect during dobutamine stress echocardiography (DSE). This study sought to evaluate the prognostic implications of NSVT during DSE on 1,266 consecutive dobutamine stress echocardiograms performed over 1 year. NSVT, defined as > or =3 consecutive ventricular premature beats, occurred in 65 of 1,266 patients (5.1%). There was no absolute increased risk in all-cause mortality between the NSVT and no NSVT groups (22% vs 17%, p = 0.15) during the 3-year follow-up. Survival curves generated by the Kaplan-Meier method also demonstrated no increased risk in mortality between the NSVT and no NSVT groups (p = 0.43). When only studies with negative results for inducible ischemia were taken into account, survival curves showed no significant difference in all-cause mortality (p = 0.26). Studies with negative results for inducible ischemia were also stratified according to the ejection fraction (EF). Patients without inducible ischemia and mildly reduced to normal EFs (>0.45) did not have significant differences in survival between the NSVT and no NSVT groups over the 3-year follow-up (p = 0.86). However, patients without inducible ischemia and moderately reduced EFs (0.35 to 0.45) who had NSVT during DSE had significantly reduced survival over the follow-up (p = 0.01).

Use of pharmaceuticals in noninvasive cardiovascular diagnosis

A number of pharmaceuticals are employed as diagnostic agents for cardiovascular diseases. Four groups of agents are reviewed here: 1) vasoactive substances employed as adjuncts to physical maneuvers in diagnosis of structural heart disease; 2) vasodilators used to produce heterogeneity of coronary flow; 3) sympathomimetic agents simulating the effects of exercise on the heart for the purpose of detection of coronary artery stenosis; and 4) ultrasonic contrast agents used to enhance myocardial imaging for the assessment of segmental wall motion. In the first group are amyl nitrate, a vasodilator, and methoxamine and phenylephrine, both vasopressors. The vasodilators of the second group are dipyridamole and adenosine. When combined with scintigraphic perfusion imaging or with echocardiographic assessment of segmental wall motion, these agents can detect single- or multiple-vessel coronary artery disease with sensitivity and specificity comparable to submaximal exercise. They are especially useful for preoperative risk assessment before noncardiac surgery. The sympathomimetic agents of the third group, dobutamine and arbutamine, increase myocardial contractility and heart rate, and dilate the peripheral vasculature. As with the vasodilators, when combined with nuclear or echocardiographic techniques they are equivalent to exercise in detection of coronary disease. They are especially useful in patients with bronchospastic disease and for assessment of myocardial viability. Agents from groups 2 and 3 have acceptable side-effect and safety profiles. The last group reviewed includes echocardiographic contrast agents that, in this investigative setting, are employed to enhance detection of segmental wall motion when used with agents from groups 2 and 3.

Dobutamine stress echocardiography: safety in diagnosing coronary artery disease

Dobutamine stress echocardiography is considered a relatively well-tolerated diagnostic modality, effective in the management of patients with known or suspected coronary artery disease. Adverse effects during testing are relatively frequent, precluding the achievement of a diagnostic end-point in about 5 to 10% of tests. These adverse effects, mostly tachyarrhythmias and arterial hypotension, are usually minor and self limiting. However, severe life-threatening complications, as well as death, also occur. By analysing Medline-quoted literature up to March 1999, we found 35 original studies from a single institution with more than 100 patients, as well as 2 multicentre studies, concerning the feasibility and safety of dobutamine stress echocardiography. In a cumulative total of 26438 tests performed, 79 life-threatening complications (such as acute myocardial infarction, asystole, ventricular fibrillation, sustained ventricular tachycardia or severe symptomatic hypotension) have been reported, giving an incidence of 1 severe adverse reaction per every 335 examinations. In addition, 29 isolated case reports have been published describing life-threatening complications during dobutamine echocardiography. In case reports, 2 deaths have been described, both due to acute cardiac rupture in patients with recent inferior myocardial infarction. Severe adverse reactions during dobutamine echocardiography can be ischaemia independent, and are independent of operator experience and are unpredictable; some complications can be late occurring and long lasting. As a consequence, the procedure must be clearly indicated, written informed consent has to be obtained from the patient, an attending physician must be present during testing, and long term observation of outpatients is useful in order to manage late complications. In conclusion, while the safety of dobutamine stress echocardiography was reported to be outstanding in early reports, further experience presents a substantially more worrying picture. This must be taken into account by both physicians and patients when assessing the risk-benefit profile of the procedure.

Relation between the extent of coronary artery disease and tachyarrhythmias during dobutamine stress echocardiography

Despite accumulating data regarding the safety of dobutamine stress testing, the possible induction of tachyarrhythmias during the test remains a major concern for physicians, particularly in patients with extensive coronary artery disease (CAD) or left ventricular dysfunction. The aim of this study is to evaluate the clinical, echocardiographic, and angiographic predictors of arrhythmias during dobutamine stress testing. Dobutamine (up to 40 microg/kg/min)-atropine (up to 1 mg) stress echocardiography was performed in 286 patients (age 58 +/- 11 years, 200 men) with suspected myocardial ischemia who underwent coronary angiography within 3 months of the test. Wall motion score index was derived using a 16 segment/4 grade score model where 1 = normal and 4 = dyskinesia. No myocardial infarction or death occurred during the test. Ventricular and supraventricular tachycardia occurred in 16 (6%) and 21 (7%) patients, respectively. Systolic blood pressure decrease > or = 40 mm Hg occurred in 7 patients (2%). Significant CAD was detected in 220 patients (77%). There was no significant difference between patients with and without tachyarrhythmias with regard to the prevalence of CAD (78% vs 77%) or the mean number of diseased coronary arteries (1.51 +/- 0.7 vs 1.45 +/- 0.8). Independent predictors of tachyarrhythmias by multivariate analysis of clinical, angiographic, and echocardiographic characteristics were a higher resting wall motion score index (p <0.01) and mole gender (p <0.05). Independent predictors of systolic blood pressure decrease > or = 40 mm Hg were a higher baseline systolic blood pressure (p <0.0001), a history of myocardial infarction (p <0.0001), and a higher resting wall motion score index (p <0.01). It is concluded that tachyarrhythmias during dobutamine stress testing are predicted by the extent of left ventricular dysfunction but not by the presence or the extent of CAD.

Complications of pharmacologic stress echocardiography in coronary artery disease

In the last few years, pharmacologic stress echocardiography is emerging as a promising diagnostic tool with a favorable cost/benefit ratio. Its main clinical applications include the assessment of coronary artery disease, the identification of viable myocardium, and risk stratification before major vascular surgery. However, cardiac (arrhythmic, ischemic, or hemodynamic) as well as noncardiac complications have been reported, so that a risk/benefit analysis is advisable in view of the extensive introduction of this technique in the clinical arena. The most popular pharmacologic agents employed for stress echocardiography are dipyridamole, dobutamine, and adenosine. A comparative analysis with exercise stress testing, the classical standard a reference of all ischemia-provoking tests, confirms that in terms of safety and tolerability pharmacologic stress echocardiography may be considered a good alternative in patients unable to exercise maximally. No appreciable difference among the safety profiles of the most common pharmacologic agents has been found, but a careful evaluation of the risk/benefit ratio is advisable for any stressor in the individual patient by considering the relative importance of the expected diagnostic contribution and the pharmacodynamic impact of the test. Finally, adequate training of the operator and monitoring of the patient during stress and recovery are essential for getting optimal safety conditions.