Peter R Nierop

Heart rhythm during syncope and presyncope: results of implantable loop recorders.

NIEROP, P.R., et al.: Heart Rhythm During Syncope and Presyncope: Results of Implantable Loop Recorders. Ambulatory ECG monitoring in patients with recurrent syncope is nondiagnostic in the majority of cases. Recently, an ECG implantable loop recorder (ILR) has been introduced. The ILR performs continuous ECG monitoring over a period of at least 14 months. From February 1997 to September 1999, 35 patients underwent implantation of an ILR. During a mean follow‐up of 11 ± 8 months, 24 (69%) patients had recurrent syncope or presyncope events. Four (11%) patients were not capable of activating the ILR to save the event. A symptom‐rhythm correlation could be studied in 20 (83%) of 24 patients. Forty of 44 recurrences were captured by the ILR. There were 14 (40%) patients with at least one syncopal episode. An arrhythmic cause for syncope was found in eight of them (bradycardia in four and tachycardia in four). In the other six patients the heart rhythm was normal. In 17 (49%) patients with 1‐year follow‐up, the mean syncope event rate 12 months before ILR implantation was 4.7 ± 2.4, whereas the mean syncope event rate 12 months after ILR implantation was 1.3 ± 0.7 (P < 0.01). Resolution of symptoms was observed in 6 (17%) patients. These patients were significantly younger than patients without resolution (50 ± 18 vs 69 ± 14 years, p < 0.01) and five were women. Three (9%) patients died during follow‐up, all of them were noncompliant during their follow‐up. In conclusion, the ILR made symptom—rhythm correlation possible in 83% of patients with recurrent syncope. Syncope recurrences decreased significantly after implantation of the device, especially in the younger patients. Noncompliant patients had a high mortality rate.

Gender differences in the accuracy of dobutamine stress echocardiography for the diagnosis of coronary artery disease

The accuracy of dobutamine stress echocardiography (DSE) for the diagnosis of coronary artery disease (CAD) has not been yet evaluated in women. We studied the effect of gender on the accuracy of DSE for the diagnosis of CAD in 306 consecutive patients (210 men and 96 women) with limited exercise capacity and suspected myocardial ischemia who underwent coronary angiography within 3 months of DSE. There were no serious complications during DSE. Men had a higher prevalence of nonsustained ventricular tachycardia (7% vs 0.03%, p <0.05) and supraventricular tachycardia (9% vs 0.03%, p <0.05) during the test compared with women. Peak stress rate-pressure product was not different in men and women (18,140 +/- 4,187 vs 18,543 +/- 4,223). Significant CAD (> or =50% luminal diameter stenosis) was present in 171 men (81%) and in 62 women (65%, p <0.005). The sensitivity, specificity, and accuracy of ischemic pattern at DSE for the diagnosis of significant CAD were 76% (confidence interval [CI] 67 to 84), 94% (CI 89 to 99), and 82% (CI 75 to 90) in women and 73% (CI 67 to 79), 77% (CI 71 to 83), and 74% (CI 68 to 80) in men, respectively. Overall specificity was higher in women than in men (p <0.05). Regional accuracy of DSE was significantly higher in women than in men in the 3 arterial regions (84% [CI 79 to 88] vs 75% [CI 72 to 79], p <0.005). It is concluded that DSE is a safe and feasible method for the diagnosis of CAD in women. The overall specificity and the regional accuracy of DSE are higher in women than in men. Further studies are required to evaluate the functional significance of these findings and their reproducibility in different patient populations.

Relation between contractile response of akinetic segments during dobutamine stress echocardiography and myocardial ischemia assessed by simultaneous thallium-201 single-photon emission computed tomography

There are no standard criteria for the diagnosis of myocardial ischemia in akinetic segments during dobutamine stress echocardiography (DSE). The aim of the study was to assess the relation between different responses of akinetic segments during DSE and ischemia assessed by thallium-201 single-photon emission computed tomography (SPECT). Dobutamine-atropine stress echocardiography with simultaneous stress-reinjection thallium-201 SPECT was performed in 67 patients with old myocardial infarction significant and coronary artery stenosis. Fourteen myocardial segments were matched for both DSE and SPECT. Ischemia on SPECT was defined as reversible thallium defects. In 257 akinetic segments, 4 patterns during DSE were identified: (1) biphasic response in 41 segments (16%), defined as improvement at low dose (5 to 10 microgram/kg/min) followed by worsening at high dose; (2) persistent akinesia in 155 segments (60%); (3) akinesia becoming dyskinesia in 39 segments (15%); and (4) sustained improvement in 22 segments (9%). Reversible thallium defects were detected in 21 segments (51%) in group 1, in 20 segments (13%) in group 2, none in group 3, and in 2 segments in group 4 (9%). The prevalence of reversible defects in biphasic segments was higher compared with other patterns (p <0.00001 vs groups 2 and 3, p <0.005 vs group 4). The ischemic perfusion defect score was significantly higher in group 1 than group 2. The positive predictive value of biphasic response for reversible thallium defects was similar to that of stress-induced dyssynergia in normal segments at rest (51% vs 58%). It is concluded that of the various responses of akinetic segments to dobutamine infusion, the biphasic response is associated with the highest prevalence and greatest severity of ischemic on thallium SPECT. Observation of contractile response at both low- and high-dose DSE is a valuable approach for the diagnosis of myocardial ischemia in akinetic segments.

Comparison of Dobutamine Stress Echocardiography and 99m-Technetium Sestamibi SPECT Myocardial Perfusion Scintigraphy for Predicting Extent of Coronary Artery Disease in Patients With Healed Myocardial Infarction

This study compares the value of dobutamine stress echocardiography and 99m-technetium methoxyisobutyl-isonitrile (MIBI) single-photon emission computed tomography (SPECT) in the assessment of extent and location of coronary narrowing in patients with healed myocardial infarction. Dobutamine (up to 40 microg/kg/ min)-atropine (up to 1 mg) stress echocardiography (DSE) in conjunction with MIBI SPECT was performed in 72 patients (52 men, mean age 57 +/- 11 years) with healed myocardial infarction referred for evaluation of myocardial ischemia. Ischemia was defined as new or worsened wall motion abnormalities at DSE and reversible perfusion defects at MIBI SPECT. Significant stenosis (> or = 50% luminal diameter stenosis) of the infarct-related artery was detected in 45 patients and of other coronary arteries in 22 patients. Sensitivity and specificity of remote ischemia for diagnosis of remote coronary stenosis were 68% (95% confidence interval [CI] 57 to 80) and 93% (CI 86 to 99) for DSE, and 64% (CI 52 to 76), and 90% (CI 83 to 98) for MIBI SPECT, respectively. The positive predictive value and specificity of peri-infarction ischemia for the diagnosis of infarct-related artery stenosis were 89% (CI 81 to 97) and 82% (CI 73 to 92) for DSE, and 87% (CI 79 to 95) and 82% (CI 73 to 92) for SPECT, respectively. The agreement between both techniques was higher for the diagnosis of remote than peri-infarction ischemia (84% vs 66%, p = 0.02). It is concluded that in patients with myocardial infarction undergoing dobutamine stress testing, both echocardiography and MIBI SPECT are clinically useful methods for the diagnosis of remote and infarct-related coronary artery stenosis.

Optimal Criteria for the Diagnosis of Coronary Artery Disease by Dobutamine Stress Echocardiography

Abstract The diagnosis of coronary artery disease (CAD) on the basis of inducible ischemia in ≥2, rather than ≥1, segments was suggested to improve specificity of dobutamine stress echocardiography (DSE). However, the impact of using these criteria on the sensitivity and accuracy of DSE was not studied. We studied the accuracy of DSE (up to 40 μg/kg/min) for the diagnosis of CAD in 290 patients with suspected myocardial ischemia using the criteria of ≥1 and ≥2 ischemic segments. Ischemia was defined as new or worsening wall motion abnormalities using a 16-segment model. Among the 85 patients without previous myocardial infarction, significant CAD was detected in 51 (60%). Sensitivity, specificity, and accuracy of DSE using ≥1 ischemic segment were 73%, 85%, and 78%, respectively. Those using ≥2 segments were 67%, 94%, and 78%, respectively (p = NS). Regional specificity improved by using ≥2 segments (91% vs 96%, p

Relation between ST segment elevation during dobutamine stress test and myocardial viability after a recent myocardial infarction.

OBJECTIVE: To assess the relation between ST segment elevation during the dobutamine stress test and late improvement of function after acute Q wave myocardial infarction. PATIENTS AND DESIGN: 70 patients were studied a mean (SD) 8 (3) days after acute myocardial infarction with high dose dobutamine-atropine stress echocardiography and a follow up echocardiogram at 85 (10) days. A score model based on 16 segments and four grades was used to assess left ventricular function. Functional improvement was defined as a reduction of wall motion score > or = 1 in > or = 1 segments at follow up. INTERVENTION: Myocardial revascularisation was performed in 23 patients (33%) before follow up studies. RESULTS: ST segment elevation occurred in 40 patients (57%). Late functional improvement occurred in 35 patients (50%). Functional improvement was more common in patients with ST segment elevation (68% v 30%, P < 0.005) and they had a higher mean (SD) number of improved segments at follow up (1.9 (2.2) v 0.5 (1.1), P < 0.005). The wall motion score index decreased between baseline and follow up in patients with ST segment elevation (1.54 (0.50) v 1.48 (0.43), P < 0.05) but not in patients without ST segment elevation (1.39 (0.60) v 1.45 (0.47)). The accuracy of ST segment elevation for the prediction of functional improvement was similar to that of low dose dobutamine echocardiography in patients with anterior infarction (80% v 83%) and in patients who underwent revascularisation (78% v 83% respectively). CONCLUSION: In patients with a recent Q wave myocardial infarction, dobutamine-induced ST segment elevation is a valuable marker of myocardial viability particularly when the test is performed without or with suboptimal echocardiographic imaging.

The functional significance of chronotropic incompetence during dobutamine stress test

OBJECTIVE To investigate the functional significance of chronotropic incompetence during dobutamine stress echocardiography. PATIENTS AND METHODS The functional significance of chronotropic incompetence was evaluated during dobutamine stress echocardiography in 512 patients without β blocker treatment who underwent dobutamine stress echocardiography (up to 40 μg/kg/min) and completed the protocol or reached the target heart rate. Mean (SD) age was 60 (12) years (313 men, 199 women). Chronotropic incompetence was defined as failure to achieve 85% of the maximum exercise heart rate predicted for age and sex (220 − age in men; 200 − age in women) at maximum dobutamine dose. RESULTS Chronotropic incompetence occurred in 196 patients (38%). Affected patients were significantly younger, more likely to be men (both p << 0.001) and smokers (p < 0.05), had a higher prevalence of previous myocardial infarction (p < 0.005) and resting wall motion abnormalities (p < 0.05), and had a lower resting heart rate (p << 0.001) and systolic blood pressure (p << 0.001) than patients without chronotropic incompetence, but there was no difference in the overall prevalence of ischaemia and significant coronary artery disease. By multivariate analysis, independent predictors of chronotropic incompetence were a lower resting heart rate (p << 0.001), younger age (p << 0.001), and male sex (p << 0.001). CONCLUSIONS The relations among sex, age, and chronotropic incompetence show the need to titrate the dobutamine dose using specific data based on age and sex related heart rate responses to dobutamine rather than to an exercise stress test. Obtaining specific heart rate criteria is necessary to determine whether chronotropic incompetence represents a real failure to achieve a normal response or is the result of applying an inappropriate gold standard.

Impact of Severity of Coronary Artery Stenosis and the Collateral Circulation on the Functional Outcome of Dyssynergic Myocardium After Revascularization in Patients With Healed Myocardial Infarction and Chronic Left Ventricular Dysfunction

The aim of this study was to assess the influence of the severity of coronary artery stenosis and the grade of collateral circulation on myocardial viability in patients with chronic left ventricular (LV) dysfunction undergoing coronary artery bypass grafting. Forty patients (age 59 +/- 8 years) with old myocardial infarction were studied by dobutamine stress echocardiography (DSE) before coronary artery bypass grafting. LV function was assessed using a 16-segment, 5-grade score model. Viability and functional recovery were respectively defined as a reduction in wall motion score > or = 1 at low-dose DSE and at follow-up echocardiograms obtained 3 months after surgery. There were 56 stenotic coronary arteries subtending severely dyssynergic myocardial segments, of which 38 were occluded. Among 186 severely dyssynergic segments, functional recovery occurred in 42 (23%). There was no significant difference between myocordial regions with patent or occluded coronary arteries with respect to prevalence of viability or functional recovery and percentage of viable or recovered segments relative to the total number of dyssynergic segments. In patients with total occlusion, these parameters were not different between regions with different collateral grades. Sensitivity, specificity, and accuracy of low-dose DSE for prediction of regional functional recovery were 71%, 90%, and 86%, respectively. It is concluded that in patients with chronic LV dysfunction, the presence of total occlusion of coronary arteries supplying severely dyssynergic regions does not imply a lower prevalence or extent of functional recovery after revascularization, regardless of the grade of angiographically visualized collaterals. Low-dose DSE can identify myocardial regions with a high probability of functional improvement after revascularization regardless of the severity of underlying coronary stenosis or collateralization of the involved coronary vessel.

Dobutamine-atropine stress myocardial perfusion SPECT imaging in the diagnosis of graft stenosis after coronary artery bypass grafting

ObjectiveTo assess the accuracy of dobutamine stress myocardial perfusion single photon emission computed tomographic imaging (SPECT) for the diagnosis of vascular stenosis after coronary artery bypass grafting (CABG).BackgroundExercise thallium scintigraphy is a clinically useful method for the diagnosis of graft stenosis after CABG. Although dobutamine perfusion scintigraphy is an alternative method for the evaluation of patients with limited exercise capacity, its value in the diagnosis of vascular stenosis after CABG has not been studied.MethodsDobutamine (up to 40 μg/kg/min)-atropine (up to 1 mg) stress test in conjunction with myocardial perfusion SPECT imaging (201Tl or 99m technetium sestamibi [MIBI]) was performed in 71 patients (mean age 58±9 years, 57 men) with limited exercise capacity referred for evaluation of myocardial ischemia 3.7±3.5 years after CABG. Significant vascular stenosis was defined as ≥50% luminal diameter stenosis of a graft or a native nongrafted coronary artery and was predicted on the basis of reversible perfusion abnormalities.ResultsSignificant vascular stenosis was detected in 52 patients. Sensitivity, specificity, and accuracy of reversible perfusion defects at dobutamine SPECT for the overall diagnosis of vascular stenosis were 81%, confidence interval (CI) 72 to 90, 79%, CI 69 to 88, and 80%, CI 71 to 90, respectively. Significant vascular stenosis was detected in 73 arterial regions. Sensitivity, specificity, and accuracy of dobutamine SPECT for the diagnosis of regional vascular stenosis were 66%, CI 58 to 74, 83%, CI 76 to 89, and 74%, CI 67 to 81, respectively. Patients with multivessel stenosis had a higher number of ischemic segments (1.6±1.3 vs 1±1, P<.05) and ischemic perfusion score (3.2±2.7 vs 2.2±2.3, P<.05) than patients with single-vessel stenosis, respectively. Significant graft stenosis was detected in 67 graft regions. Sensitivity, specificity, and accuracy of dobutamine SPECT for the diagnosis of regional graft stenosis were 64%, CI 56 to 73, 85%, CI 78 to 91, and 74%, CI 66 to 82, respectively.ConclusionDobutamine stress myocardial perfusion SPECT imaging is a useful method for the diagnosis of significant vascular stenosis after CABG in patients with limited exercise capacity.

Dobutamine 99Tcm-MIBI SPET myocardial perfusion scintigraphy in the prediction of restenosis after percutaneous transluminal coronary angioplasty in patients unable to perform an exercise stress test

After successful percutaneous transluminal coronary angioplasty (PTCA), restenosis occurs in a relatively high proportion of patients. Exercise thallium scintigraphy is a useful method for the detection of restenosis. In patients unable to exercise, dobutamine perfusion scintigraphy may represent a feasible alternative. However, its diagnostic accuracy in this clinical setting has not been evaluated. We studied 40 patients (29 males, 11 females) aged 57 ± 9 years, at a mean of 185 ± 80 days after successful PTCA with a high-dose dobutamine (up to 40 μg kg−1 min−1) stress test, in conjunction with 99Tcm-methoxyisobutyl isonitrile (99Tcm-MIBI) single photon emission tomography (SPET). Significant restenosis was defined as a 50% luminal diameter stenosis of a coronary segment with previous PTCA and was predicted on the basis of the occurrence of reversible perfusion defects in the corresponding territories. Reversible perfusion defects occurred in 20 of 29 arteries with and in 4 of 17 arteries without restenosis. The sensitivity of dobutamine MIBI for the detection of restenosis in arteries with previous PTCA was 69% (CI = 56–82), the specificity 76% (CI = 64–89), the positive predictive value 83% (CI = 73–94), the negative predictive value 59% (CI = 45–73) and accuracy 72% (CI = 59–85). The overall sensitivity of 99Tcm-MIBI SPET for the diagnosis of significant coronary stenosis (including arteries without previous PTCA) on a patient basis was 79% (CI = 67–92), the specificity 82% (CI = 70–94) and accuracy 80% (CI = 68–92). The sensitivity of 99Tcm-MIBI SPET was significantly higher than that of electrocardiography (79 vs 38%, P < 0.005). It is concluded that dobutamine 99Tcm-MIBI SPET is a useful method for the detection of restenosis after PTCA in patients unable to perform an exercise stress test.