Sinus node deceleration during dobutamine perfusion scintigraphy as a marker of inferior ischemia

Prognostic significance of sinus deceleration during dobutamine stress echocardiography test following acute myocardial infarction

Background/Aim. Chronotropic incompetence during exercise stress testing after acute myocardial infarction is an indicator of ischemia or impaired left ventricular function. On the other side, infusion of dobutamine leads to a typical dose-dependent increase in heart rate. The aim of this study was to evaluate of paradoxical sinus deceleration during dobutamine stress echocardiography (DSE), as the sign of ischemia and impaired left ventricular function, or the consequence of infarction localization, and the estimation of prognostic significance after acute myocardial infarction. Methods. Our investigation comprised 81 patients hospitalized because of the acute myocardial infarction, and all of them had uncomplicated infarction. Fifty five patients were treated with thrombolytic therapy (67.9%); 53 patients (65.4%) had anterior myocardial infarction, and 28 patients (34.6%) had inferoposterior localization of myocardial infarction. After 10-12 days all of them underwent dobutamine stress echocardiography examination. During the next 3-6 months, the patients underwent coronary angiography. The average follow-up period was 36?22 months. Results. A decrease in heart rate occurred at the dobutamine doses increasing from 15-40mcg/kg/min in 9 (11.1%) of the patients, in 1 patient with an anterior localization and in 8 patients with an inferoposterior localization. The decrease was sudden in 4 (44.4%), and gradual in 5 (55.6%) of the patients. In 3 patients (33.3%) junction rhythm was developed, and in 2 patients (22.2%) AV block II-III. Only in 2 of them, there was a worsening of regional function during a high dose dobutamine infusion, but 7 of them showed an improvement during a low dose. In 7 (77.8%) of the patients there was a simultaneous decrease in blood pressure. Coronary angiographic examination showed that in 4 (44.4%) of the patients there was a significant coronary artery disease and they underwent the revascularization procedure. During the follow up period, there was not any significant arrhythmic disorder in that group of the patients or repeated hospitalization because of postinfarction angina, re-infarction, or heart failure. Conclusion. We could conclude that paradoxical sinus deceleration is not only an indicator of a significant coronary artery disease and ?bad left ventricle?. It also may occur as a consequence of vasodepressor reflex (Bezold-Jarisch), even after acute myocardial infarction, without influencing a long-term prognosis.

Yield of stress single-photon emission computed tomography in asymptomatic patients with diabetes

BACKGROUND

Patients with diabetes without clinically apparent coronary artery disease are at increased risk of cardiac death. The value of screening stress testing in these patients remains controversial. The goal of this study was to examine the yield of stress single-photon emission computed tomography (SPECT) in asymptomatic diabetic patients.

METHODS

The results of stress SPECT in patients without prior myocardial infarction or coronary revascularization were compared in asymptomatic diabetics (n = 1738) versus symptomatic diabetic patients (n = 2998), asymptomatic nondiabetic patients (n = 6215), and symptomatic nondiabetic patients (n = 16,214).

RESULTS

Abnormal scans were present in 58.6% of asymptomatic diabetic patients, approximately equal to the percentage in symptomatic diabetic (59.5%) (P = not significant) and higher than in asymptomatic nondiabetic (46.2%) (P <.001) and symptomatic nondiabetic (44.4%) (P <.001) patients. The breakdown of high-risk scans followed a similar pattern in the 4 patient subsets: asymptomatic diabetic, 19.7% versus symptomatic diabetic, 22.2% (P =.051); asymptomatic nondiabetic, 11.1% (P <.001); and symptomatic nondiabetic, 12.5% (P <.001). Patients with diabetes had more electrocardiographic and scan evidence for silent myocardial infarction versus those without diabetes.

CONCLUSIONS

Asymptomatic diabetic patients have a high prevalence of both abnormal and high-risk SPECT scans. The finding that approximately 1 in 5 of these individuals has a high-risk scan suggests a potentially more widespread application of screening stress SPECT in asymptomatic diabetic patients to identify those with severe coronary artery disease.

Dobutamine stress myocardial perfusion imaging

In patients with limited exercise capacity and (relative) contraindications to direct vasodilators such as dipyridamole or adenosine, dobutamine stress nuclear myocardial perfusion imaging (DSMPI) represents an alternative, exercise-independent stress modality for the detection of coronary artery disease (CAD). Nondiagnostic test results (absence of reversible perfusion defects with submaximal stress) do occur in approximately 10% of patients. Serious side effects during DSMPI are rare, with no death, myocardial infarction or ventricular fibrillation reported in three DSMPI safety reports for a total of 2,574 patients. On the basis of a total number of 1,014 patients reported in 20 studies, the sensitivity, specificity and accuracy of the test for the detection of CAD were 88%, 74% and 84%, respectively. Mean sensitivities for one-, two- and three-vessel disease were 84%, 95% and 100%, respectively. The sensitivity for detection of left circumflex CAD (50%) was lower, compared with that for left anterior descending CAD (68%) and right CAD (88%). The sensitivity of predicting multivessel disease by multiregion perfusion abnormalities varied widely, from 44% to 89%, although specificity was excellent in all studies (89% to 94%). In direct diagnostic comparisons, DSMPI was more sensitive, but less specific, than dobutamine stress echocardiography and comparable with direct vasodilator myocardial perfusion imaging. In the largest prognostic study, patients with a normal DSMPI study had an annual hard event rate less than 1%. An ischemic scan pattern provided independent prognostic value, with a direct relationship between the extent and severity of the perfusion defects and prognosis. In conclusion, DSMPI seems a safe and useful nonexercise-dependent stress modality to detect CAD and assess prognosis.

Prognostic implications of a normal dobutamine-atropine stress echocardiogram in patients with chest pain

To assess the prognostic significance of a normal dobutamine-atropine stress echocardiogram in relation to the pretest probability of coronary artery disease (CAD), 200 consecutive patients (86 men and 114 women, mean [SD] age 59 [13] years) with a stable chest pain syndrome and a normal dobutamine-atropine stress echocardiogram were followed-up for 21 +/- 16 months. Outcome events were cardiac death, non-fatal myocardial infarction, and coronary revascularization procedures. Low (<10%), intermediate (10% to 80%), and high (>80%) pretest probabilities of CAD were present in 27 (14%), 108 (54%), and 65 (33%) patients, respectively. During follow-up, 2 patients (annual event rate 0.6%) had cardiac death, none had nonfatal myocardial infarction, and 4 patients (annual event rate 1.1%) underwent a coronary revascularization procedure. All patients with cardiac events had high pretest probabilities of CAD. Patients with cardiac death (but unproven significant CAD) had maximal tests without angina or ischemic electrocardiographic changes. In contrast, all patients with subsequent coronary revascularization had dobutamine-induced angina or ischemic electrocardiographic changes, and all except one study were submaximal. We conclude that patients with a stable chest pain syndrome and normal findings on dobutamine-atropine stress echocardiograms have an excellent cardiac prognosis. However, patients with typical angina, high pre-test probabilities of CAD, and stress-induced angina or ischemic electrocardiographic changes, and in particular those with submaximal stress, still appear to be at risk for functionally important CAD despite a normal dobutamine-atropine stress echocardiogram.

Is dobutamine-induced sinus node deceleration a marker of significant stenosis of the right coronary artery?

STUDY OBJECTIVES

Sinus node deceleration during exercise is a highly specific marker for significant stenosis of the right coronary artery. Prior studies of dobutamine-induced sinus node deceleration have contained relatively few patients, and the purpose of this study was to determine if sinus node deceleration is an accurate marker of right coronary artery disease in a much larger study population.

DESIGN

Dobutamine stress echocardiography was performed in a cohort of patients, and submaximal exercise testing and coronary angiography were performed in most of the patients.

SETTING

A university hospital.

PATIENTS AND INTERVENTIONS

Dobutamine stress echocardiography was performed in 757 patients, and symptom-limited submaximal treadmill ECG was also performed in 571 of those patients. Sinus node deceleration was defined as a decrease in the heart rate at peak stress compared with that at the previous stage. Coronary angiography was performed in 631 patients, 184 of whom were found to have significant right coronary artery stenosis.

MEASUREMENTS AND RESULTS

The prevalence of dobutamine-induced sinus node deceleration (54 [7%] of 757 patients) was significantly higher than that induced during treadmill ECG (3 [0.5%] of 571 patients; p<0.001). The prevalence of inferior ischemia by echocardiography did not differ between patients with dobutamine-induced sinus node deceleration (26%) and those without (30%). There was also no significant difference in the prevalence of right coronary artery stenosis between the two groups (27% vs 29%). The specificity of dobutamine-induced sinus node deceleration for detecting significant stenosis of the right coronary artery (92%) was higher than that of echocardiography (84%; p<0.00), but the positive predictive value was lower (28% vs 64%; p<0.001).

CONCLUSIONS

Although sinus node deceleration during dobutamine stress echocardiography is a relatively more common finding, it does not always accompany significant stenosis in the right coronary artery. The mechanism for its induction is postulated to be vagal activation caused by multiple factors.

Methodology, feasibility, safety and diagnostic accuracy of dobutamine stress echocardiography

Large numbers of patients referred for evaluation of chest pain are unable to perform adequate, diagnostic exercise testing. In these patients, dobutamine stress echocardiography (DSE) represents an alternative, exercise-independent stress modality. Apart from the approximately 5% of patients with an inadequate acoustic window, 10% of patients referred for this test have nondiagnostic (submaximal negative) test results. Serious side effects during or shortly after DSE are uncommon, with ventricular fibrillation or myocardial infarction occurring in approximately 1 of 2,000 studies. No deaths have been reported. On the basis of a total number of 2,246 patients, reported in 28 studies, the sensitivity, specificity and accuracy of the test for the detection of coronary artery disease (CAD) were 80%, 84% and 81%, respectively. Mean sensitivities for one-, two- and three-vessel disease were 74%, 86% and 92%, respectively. The sensitivity for detection of disease in the left circumflex coronary artery (55%) was lower, both compared with that for left anterior descending (72%) and right coronary artery disease (76%). The sensitivity of predicting multivessel disease by multiregion echocardiographic abnormalities varied widely, from 8% to 71%. In direct comparisons, DSE was superior to exercise electrocardiography and dipyridamole echocardiography and comparable to exercise echocardiography and radionuclide imaging. DSE is a useful, feasible and safe exercise-independent stress modality for assessing the presence, localization and extent of CAD.

Paradoxical sinus deceleration during dobutamine stress echocardiography: description and angiographic correlation

OBJECTIVES

This report characterizes the paradoxical sinus deceleration occasionally observed during dobutamine stress testing and determines its relation to myocardial ischemia.

BACKGROUND

Dobutamine stress echocardiography is widely accepted as a noninvasive tool for evaluating coronary artery disease. With infusion of dobutamine, there is typically a dose-dependent increase in heart rate. However, in some patients, a paradoxical decrease in heart rate has been observed during high dose dobutamine infusion.

METHODS

In 181 consecutive patients undergoing both dobutamine stress echocardiography and coronary angiography, electrocardiographic (ECG) data collected during dobutamine infusion were reviewed to identify patients with a decrease in heart rate. The clinical, stress echocardiographic, hemodynamic and angiographic correlates of patients with a decrease in heart rate were reviewed.

RESULTS

A decrease in heart rate ranging from 7 to 64 beats/min occurred during high dose dobutamine infusion in 14 patients (8%, 95% confidence interval [CI] 6% to 10%), including 3 in whom a junctional rhythm developed. The decrease was sudden in five patients (36%, 95% CI 13% to 65%) and gradual in nine (64%, 95% CI 35% to 87%). A decrease in blood pressure (12 patients [86%], 95% CI 57% to 98%) with simultaneous chest pain (7 patients [50%], 95% CI 23% to 77%) and nausea (5 patients [36%], 95% CI 13% to 65%) was common. Significant coronary artery disease (> or = 50% diameter stenosis) was present in 8 (57%) of 14 patients (95% CI 29% to 82%). Two patients (14%, 95% CI 2% to 43%) had no clinical, ECG or echocardiographic evidence of ischemia and no significant coronary artery disease by angiography. There was no increased incidence of right coronary artery stenosis in patients with paradoxical sinus deceleration.

CONCLUSIONS

Paradoxical sinus deceleration occurs in 8% of patients during dobutamine stress testing. Although most often observed in patients with coronary artery disease, it can occur in the absence of ischemia and coronary artery disease, and in some patients may be due to a vasodepressor reflex.