Exercise versus dobutamine-induced ST elevation in the infarct-related electrocardiographic leads: clinical significance and correlation with functional recovery.

BACKGROUND: The clinical significance of stress-induced ST elevation early after acute myocardial infarction and its relation to functional recovery remain controversial. The aims of this study were (1) to determine the incidence of ST elevation during dobutamine and exercise tests and (2) to assess the relative accuracy of exercise and dobutamine ST elevation for predicting functional recovery after acute myocardial infarction. METHODS AND RESULTS: We investigated 52 patients who underwent supine exercise (from 25 W to maximal charge) and dobutamine (from 5 to 40 microg/kg per minute and up to 1 mg atropine) stress electrocardiography in the same position. ST elevation was defined as new or worsening at >1 mm, 80 ms after J point. Echocardiography and quantitative angiography were available in all patients before hospital discharge. The follow-up resting echocardiogram was recorded 30 +/- 6 days after the acute event. ST elevation developed during 30 (58%) dobutamine and 24 (46%) exercise tests. The sum of ST elevation was higher during dobutamine testing (7.7 +/- 3.8 mm) than during exercise (5.5 +/- 2.5 mm) (P =.03). A low peak creatine kinase level was the single independent predictor of dobutamine-induced ST elevation. Functional improvement occurred in 35 patients. Two independent predictors of functional recovery were selected from multivariate analysis: dobutamine ST elevation (chi(2) = 9.1; P =.0026) and low peak creatine kinase level (chi(2) = 5.1; P =.025). When dobutamine ST elevation was not included in multivariate analysis, exercise-induced ST elevation emerged as an independent predictor of functional recovery (chi(2) = 5.0; P =.023). Significant linear correlation was found between the sum of ST elevation at peak dobutamine stress and the extent of functional recovery (r = 0.87; P <.0001). In contrast, no correlation was observed with exercise ST elevation (r = 0.06; P = not significant). CONCLUSIONS: Stress-induced ST elevation is an ancillary sign of viable myocardium that can recover. The sum of ST elevation at peak dobutamine stress correlates with the extent of functional recovery.

Identification of viable myocardium early after acute myocardial infarction using closed-loop arbutamine echocardiography: comparison with positron emission tomography.

OBJECTIVE: This study sought to evaluate the safety and efficacy of arbutamine echocardiography in identifying contractile reserve and predicting functional improvement early after acute myocardial infarction (AMI). METHODS AND RESULTS: Seventeen patients with first AMI underwent arbutamine echocardiography 48 to 96 hours after AMI. Arbutamine was infused by a closed-loop delivery device. The heart rate slope was 4 beats/min and the heart rate target was 20 beats/min above baseline heart rate. A follow-up echocardiogram was obtained one month later. N-13 ammonia and F-18 FDG positron emission tomographic (PET) imaging were performed 6 +/- 2 days after AMI, before coronary angiography. Mean duration of arbutamine infusion was 6 +/- 2 min. There was no complication and there were no major side effects. Myocardial viability was identified with PET in 15 of the 17 patients. Contractile reserve was observed in 10 patients during arbutamine infusion. Functional recovery was identified in 12 patients. Sensitivity, specificity and accuracy of PET and arbutamine echocardiography for predicting functional recovery were 100%, 40%, 76% and 67%, 80%, 84%, respectively. CONCLUSIONS: Low-dose arbutamine stress testing is safe early after AMI. Contractile reserve can be rapidly identified by echocardiography and is specific, but moderately sensitive for predicting reversible dysfunction.

Assessment of ultra low frequency band power of heart rate variability: validation of alternative methods.

UNLABELLED: Alternative methods for assessing ULF spectral power using data from commercial Holter analysers were studied. Different heuristics for ULF calculation were compared with standard research software-based determination of ULF. SETTING: University Hospital. PATIENTS: 43 patients in NYHA classes I-IV heart failure and seven normals of similar ages. METHODS: SDNN, SDANN, ULF, VLF, LF, HF calculated from 24 h Holter monitoring using Oxford scanner software (method 1). ULF power also calculated by subtracting the sum of VLF. LF and HF powers obtained from the Holter scanner from the total variance (method 2) from 2 x ln(SDANN) (method 3), and by performing a standard, research-quality 24-h EFT analysis on the beat files (standard). Results of methods 1-3 were compared with standard using two-way ANOVA with repeated measures, regression analysis and a graphical technique. RESULTS: ULF calculated by method 1 correlated r=0.66 with standard but means differed substantially. In contrast, ULF calculated by method 2 correlated r=0.99 with standard with no significant differences between means. ULF calculated from SDANN (method 3) correlated r=0.983 with standard but means, while similar, were significantly lower (P=0.005). CONCLUSION: ULF reported by commercial HOLTER software is not equivalent to ULF power derived from 24 h FFT analysis. ULF calculated by method 2 can be considered equivalent to the ULF derived by standard 24-h FFT. ULF estimated by method 3 offers direct ULF power estimation from a temporal measure of HRV and can be useful when spectral values are not available.

ST-segment elevation during dobutamine stress testing predicts functional recovery after acute myocardial infarction.

OBJECTIVES: The aims of this study were (1) to assess the relation between ST-segment elevation and wall motion response occurring during dobutamine testing and (2) to evaluate the usefulness of stress-induced ST-segment elevation for predicting functional recovery after acute myocardial infarction. BACKGROUND: Clinical significance of stress-induced ST-segment elevation after acute myocardial infarction remains controversial. According to previous studies, it may reflect a larger infarcted area, depressed left ventricular function, left ventricular aneurysm, stress-induced dyskinesia, residual myocardial ischemia, or viability in the affected region. Whether transient ST-segment elevation occurring during dobutamine testing may predict functional recovery is unknown. METHODS AND RESULTS: We studied 38 patients who underwent dobutamine stress testing early (5 +/- 2 days) after a first acute myocardial infarction. Dobutamine was infused at increasing doses from 5 to a maximum of 40 microg/kg per minute, with the addition of up to 1 mg of atropine if the target rate could not be reached by dobutamine alone. Twelve-lead electrocardiography and cross-sectional echocardiography were continuously monitored throughout the test. Dobutamine-induced ST-segment elevation was defined as a new or worsening >/=1 mm elevation, 80 ms after J point, in >/=2 infarct-related leads. Quantitative angiography was available in all patients before hospital discharge. Follow-up resting echocardiography was recorded in all patients 12 to 18 months after the acute event. ST-segment elevation was observed in 20 of the 38 patients. There were no significant differences between patients with and those without dobutamine-induced ST-segment elevation in age, site of infarction, peak level of total creatine kinase enzyme, and use of thrombolytic therapy, angioplasty, or both. Persistent akinesis without change during dobutamine stress testing was more frequently observed in patients without ST elevation (P <. 05). A biphasic response during dobutamine testing was more frequently observed in patients with ST-segment elevation (P =.01). Multivariate analysis selected 2 independent variables associated with ST-segment elevation: a biphasic response during dobutamine stress (chi-square = 7.3; P =.007) and the minimal lumen diameter of the infarct-related vessel at quantitative angiography (chi-square = 5.5; P <.02). Functional recovery was demonstrated in 26 patients. Sensitivity of ST-segment elevation for the prediction of functional recovery was 69%, specificity 83%, positive predictive value 90%, and accuracy 74%. Two independent variables predicting functional recovery were selected: dobutamine-induced ST-segment elevation (chi-square = 9.1; P =.003) and a biphasic response during stress (chi-square = 6.15; P =.013). CONCLUSIONS: Dobutamine-induced ST-segment elevation in the infarct-related leads is an ancillary sign of viable myocardium in jeopardy. It has a high specificity and an acceptable sensitivity for the prediction of functional recovery after acute myocardial infarction.

Wiktor stent for treatment of chronic total coronary artery occlusions: short- and long-term clinical and angiographic results from a large multicenter experience.

OBJECTIVES: This study reports the first multicenter experience with the Wiktor coil stent for treatment of chronic total coronary artery occlusions (CTOs). BACKGROUND: Percutaneous transluminal coronary angioplasty (PTCA) of CTO is associated with very high restenosis and reocclusion rates. Coronary stenting has been proposed as a means of improving outcome. However, the Wiktor device for CTOs has never been tested in a large patient sample. METHODS: From January 1993 to December 1996, 89 patients with 91 CTOs underwent Wiktor stent implantation after successful PTCA. The post-stenting regimen consisted of warfarin (Coumadin) plus aspirin in the initial 49 patients (55%) and aspirin plus ticlopidine in 40 patients (45%). RESULTS: Stenting was successful in 87 patients (98%). At 1 month, 6% of patients had subacute stent thrombosis, 3% had a major bleeding event, and 1% had access-site complications. Subacute stent thrombosis showed univariate association with warfarin therapy (p = 0.009). Angiographic follow-up was obtained in 76 (93%) of 82 eligible patients. The restenosis rate was 32%, including 4% reocclusions. By multiple logistic regression analysis, restenosis was independently associated with multiple stents (adjusted odds ratio [OR] 27.67, 95% confidence interval [CI] 4.25 to 79.95, p = 0.0008) and increasing values of occlusion length (adjusted OR 1.23, 95% CI 1.09 to 1.39, p = 0.001). Freedom from death, myocardial infarction or stented vessel revascularization was 87% and 72% at 1 and 3 years, respectively. CONCLUSIONS: Short- and long-term clinical and angiographic outcomes are favorable in patients undergoing Wiktor stent implantation in CTO. Further technical improvement is needed to reduce the restenosis rate in patients with long lesions and multiple stents.

The role of early measurement of nitrogen-13 ammonia uptake for predicting contractile recovery after acute myocardial infarction.

Previous studies have shown that the maintenance of cell membrane integrity and metabolism requires the persistence of residual myocardial blood flow. The purpose of this study was to assess the role of N-13 ammonia positron emission tomographic (PET) imaging performed early after an acute myocardial infarction for predicting functional recovery. Seventeen patients with an acute myocardial infarction were included in the study. Thirteen received thrombolytic therapy, 2 underwent immediate angioplasty of the infarct-related artery and 2 were treated with heparin. N-13 ammonia imaging was performed 6 +/- 2 days after the acute event and was followed by elective angioplasty in 13 patients. Using a 16-segment polar map display, regional N-13 ammonia uptake was expressed as a percentage of maximal segmental uptake and classified as normal (> 63%), moderately reduced (63-50%) and severely reduced (< 50%) based on values of tracer uptake obtained from healthy subjects. By echocardiographic assessment of regional wall thickening within 96 hours and at 1 month after the infarct, we examined the relationship between blood flow and functional outcome of myocardial segments in the infarct-related area. Regional wall thickening was graded on a 4-point scale: normal (1), hypokinesia (2), akinesia (3) and dyskinesia (4). Of 77 dyssynergic segments at baseline echocardiographic study, 43 had normal flow, 15 moderately reduced flow and 19 severely reduced flow. Segments with N-13 ammonia uptake > or = 50% demonstrated a significant improvement in wall thickening score at follow-up (p < 0.001), whereas segments with N-13 ammonia uptake < 50% showed no improvement in wall thickening scores (p < 0.001). The proportion of segments improving contractility by at least 1 score was significantly higher in the group of segments with N-13 ammonia uptake > 63%. The predictive value for defining functional recovery with segmental N-13 ammonia uptake > 63% was 86%. The predictive value for absence of recovery (uptake < 50%) was 54%. In conclusion, our data showed that early after an acute myocardial infarction N-13 ammonia imaging provides information regarding functional outcome.

Relation between contractile reserve and positron emission tomographic patterns of perfusion and glucose utilization in chronic ischemic left ventricular dysfunction: implications for identification of myocardial viability.

OBJECTIVES: This study sought to determine the incidence and extent of dobutamine-induced contractile reserve in myocardial regions characterized by classical and new positron emission tomographic (PET) patterns in patients with chronic ischemic left ventricular dysfunction. BACKGROUND: PET is considered the most accurate method for assessment of myocardial viability, which is traditionally identified by perfusion-metabolism mismatch. METHODS: In 23 patients, segmental wall thickening expressed by four echocardiographic scores at rest and during low dose (5 and 10 microg/kg body weight per min) dobutamine infusion and regional myocardial uptake of potassium-38 and fluorine-18 fluorodeoxyglucose (F-18 FDG) during glucose clamp were compared in 16 corresponding segments. RESULTS: Of a total of 368 segments, data analysis focused on 214 (58%) dyssynergic segments at baseline. Contractile reserve was identified with increasing incidence according to the six following PET patterns: 1) diminished perfusion and moderate reduction of F-18 FDG uptake (3 [11%] of 28 segments); 2) proportional reduction of perfusion and F-18 FDG uptake (10 [23%] of 43 segments); 3) perfusion-metabolism mismatch (19 [46%] of 41 segments); 4) preserved perfusion but moderate reduction of F-18 FDG uptake (13 [46%] of 27 segments); 5) preserved perfusion and F-18 FDG uptake (37 [59%] of 63 segments) compared with our normal database; and 6) normal perfusion but absolute increased F-18 FDG uptake (8 [73%] of 11 segments). In the latter category, only 7 of 24 segments had normal rest function. In dyssynergic segments with F-18 FDG uptake > or = 50% supplied by vessels with > or = 75% stenosis, improvement in contractility during dobutamine correlated with the presence of collateral channels. CONCLUSIONS: Myocardial regions with the traditional mismatch pattern of viability show contractile reserve in slightly < 50%. In segments with moderate reduction of F-18 FDG uptake, the contractile response to dobutamine is linked to the level of rest perfusion. Most segments with preserved perfusion and increased F-18 FDG uptake have impaired rest function, but contractile reserve is still present. These data suggest that in chronic ischemic left ventricular dysfunction, myocardial hibernation is a heterogeneous condition.

[Immediate and long-term clinical and angiographic results of the Wiktor stent in the treatment of chronic coronary occlusions]. / Risultati clinici ed angiografici immediati ed a lungo termine dello stent Wiktor nel trattamento delle occlusioni coronariche croniche.

BACKGROUND: Percutaneous transluminal coronary angioplasty (PTCA) of chronic total coronary artery occlusions is associated with very high restenosis and reocclusion rates. Coronary stenting has been proposed as a means of improving outcome. However, the Wiktor device for chronic coronary occlusion has never been tested in a large patient sample. This study reports the first multicenter experience with the Wiktor stent for treatment of chronic occlusions. METHODS: From January 1993 to December 1996, 89 consecutive patients with 91 chronic occlusions underwent Wiktor stent implantation after successful PTCA. Post-stenting regimen consisted of coumadin plus aspirin in the first 49 (55%) patients and aspirin plus ticlopidine in the following 40 (45%). RESULTS: Stenting was successful in 87 (98%) patients. At 1 month, 6% of patients had subacute stent thrombosis, 1% access-site complications and 3% major bleeding events. Stent thrombosis showed a univariate association with coumadin therapy (p = 0.009). Angiographic follow-up was obtained in 93% of 82 eligible patients. Restenosis rate was 32%, including 4% reocclusions. Through multiple logistic regression analysis, restenosis was independently associated with multiple stents (odds ratio-OR = 27.67, 95% confidence interval-CI = 4.25 to 79.95, p = 0.0008) and increasing values of occlusion length (OR = 1.23, 95% CI = 1.09 to 1.39, p = 0.001). Freedom from death, myocardial infarction or stented vessel revascularization was 87 and 72% at one and three years, respectively. CONCLUSIONS: Short- and long-term clinical and angiographic outcomes are favorable in patients undergoing Wiktor stent implantation for chronic coronary occlusion. Further technical refinements are needed to reduce restenosis rate in patients with long lesions and multiple stents.

Myocardial kinetics of potassium-38 in humans and comparison with copper-62-PTSM.

UNLABELLED: The aim of this study was to define the kinetics of 38K and its suitability to evaluate myocardial blood flow at rest and during pharmacological vasodilation in normal subjects. Potassium-38's kinetic characteristics were also compared to those of a 62Cu-pyruvaldehyde bis(n4-methyl-thio-semicarbazone) copper (II) (PTSM) flow tracer. METHODS: Potassium-38 and 62Cu-PTSM were injected at rest and after pharmacological vasodilation in six healthy volunteers. Dynamic PET acquisition was performed over 20 min and myocardial tracer retention calculated. Homogeneity of regional myocardial tracer distribution was also evaluated. RESULTS: High image quality of the heart was observed at rest and after dipyridamole with both tracers. Potassium-38 demonstrated prolonged myocardial retention with minimal lung and liver accumulation. In contrast to 38K, 62Cu-PTSM demonstrated high liver uptake which may hinder observation of the inferior wall of the myocardium. Copper-62-PTSM dipyridamole-to-rest retention ratio was 1.49. CONCLUSIONS: Potassium-38 and 62Cu-PTSM display suitable kinetics for the qualitative evaluation of blood flow and flow reserve in the human heart. Compared to 62Cu-PTSM, potassium-38, which does not show high liver uptake, may more accurately estimate blood flow in the inferior wall of the heart. However, accurate quantification of myocardial blood flow using 38K or 62Cu-PTSM retention appears to be limited to decreasing retention fraction at hyperhemic states.

Predictors of spontaneous predischarge ischemia following acute myocardial infarction.

To determine if the occurrence and the consequences of spontaneous predischarge postinfarction ischemia could be predicted early after hospital admission, a consecutive series of patients with acute myocardial infarction was studied and followed for 3 years. No patient was treated by thrombolysis. Spontaneous predischarge ischemia was defined as angina that occurred at rest before hospital discharge, at least 3 days after the acute event, and that was accompanied by electrocardiographic changes, but not by an increase in cardiac enzymes. Patients who died within the first 3 days were excluded from analysis. Among the 943 patients who survived at least 3 days, 165 (17.5%) had spontaneous ischemia before discharge. They had a higher 1-year post-hospital mortality (16 vs. 10%), but did not have significantly higher total 3-year mortality rates. Four independent, early available variables predictive of the occurrence of spontaneous ischemia were selected from a stepwise logistic discriminant analysis: history of angina before infarction, non-Q-wave infarct, absence of smoking, and higher age. Among the 165 patients with spontaneous ischemia, 3 independent variables predictive of 3-year mortality were selected stepwise: left ventricular function score, history of previous infarction, and absence of smoking.

Long-term follow-up of elderly patients with severe aortic stenosis treated by balloon aortic valvuloplasty. Importance of haemodynamic parameters before and after dilatation.

Early and late prognosis after percutaneous balloon aortic valvuloplasty (PBAV) was assessed in 38 consecutive elderly patients (mean age, 78.5 +/- 6.1 years). Significant valve opening was achieved in 35 patients. The hospital mortality was 8% (three patients); two other patients died within the first month and three underwent aortic valve replacement. At 2 years follow-up, there were 10 additional deaths (seven cardiac deaths) and five patients had symptom recurrence managed by aortic valve replacement (3) or repeat PBAV (2). Overall, six patients underwent surgery without untoward events and six had repeat PBAV. Only two out of six patients with repeat PBAV had sustained improvement; one was referred to surgery and the remaining three died soon after the second PBAV. One- and 2-year survival were respectively 72 and 62% and percentage of survivors with persistent improvement 68 and 41%. Although aortic valve area after PBAV was associated with outcome, predictors of poor long-term prognosis were primarily related to the pre-operative haemodynamic status. Patients with pulmonary resistances greater than 400 dynes cm-1 s-5 had the poorest outcome (chi 2 = 18.4-P less than 0.0001). Overall, signs of heart failure were predictors of poor long term follow-up. These data indicate that long-term success of PBAV is mainly related to the left ventricular dysfunction noted prior to intervention.

Antiarrhythmic treatment of atrial arrhythmias.

Atrial premature beats seldom require an antiarrhythmic treatment; reassurance and suppression of coffee, alcohol, and tobacco generally suffice. Acute atrial fibrillation is best treated by electrical cardioversion if it induces acute cardiovascular decompensation. If it is not poorly tolerated, the arrhythmia may be treated with digitalis at doses sufficient to keep the ventricular response rate at 70-90/min. This therapy may restore sinus rhythm, but conversion to sinus rhythm often requires the combined use of digitalis with a beta-blocker or class I antiarrhythmic drug (quinidine, disopyramide, procainamide, propafenone, or flecainide). Digitalis must be avoided in the presence of a preexcitation, and class IA agents, which facilitate atrioventricular (AV) nodal transport, must never be used without digitalis. Chemical cardioversion may also be achieved by i.v. amiodarone. Long-term prevention of recurrences after cardioversion or in the presence of recurrent paroxysmal atrial fibrillation requires digitalis combined with a class I agent, or a beta-blocker, preferably sotalol. Amiodarone is also very efficacious. Special mention should be made of atrial fibrillations of vagal or sympathetic origin, which are best treated by amiodarone, or beta-blockade (nadolol), respectively. In the presence of chronic established atrial fibrillation, digitalis in combination with a beta-blocking agent or a calcium antagonist, such as verapamil or diltiazem, may be useful to slow the ventricular response rate. If successful control cannot be obtained, catheter ablation of the AV node with implantation of a rate-responsive pacemaker must be contemplated. The therapeutic approach in patients with chronic atrial fibrillation, whether or not associated, is similar to atrial flutter.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of viable myocardium by echocardiography during dobutamine infusion in patients with myocardial infarction after thrombolytic therapy: comparison with positron emission tomography.

To assess the presence of viable myocardium salvaged by coronary artery reperfusion, 17 patients with acute anterior myocardial infarction were studied. Each received intravenous thrombolysis within the first 3 h of symptoms and underwent two-dimensional echocardiography before and during dobutamine infusion (10 micrograms/kg per min) 7 +/- 4 days after admission and positron emission tomography 9 +/- 5 days after admission. Echocardiography and positron emission tomography were again performed 9 +/- 7 months later. Six comparable segments specific for the territory of the left anterior descending artery were selected for comparison of the two techniques. Wall thickening was evaluated by using an echocardiographic score index. Segmental perfusion and glucose uptake were measured and normalized to the peak activity. A ratio of glucose uptake to perfusion was calculated for each segment. Concordant interpretation of the two techniques was found in 79% of affected segments for both acute and follow-up studies. Positron emission tomography revealed the presence of viable myocardium in 11 patients (group 1); perfusion was within normal limits in 5 of these (group 1A). Myocardial thickening improved with dobutamine infusion in these five patients, the echocardiographic score index decreasing from 12 +/- 2 at rest to 7.8 +/- 1.3 during dobutamine infusion (p = 0.003). Functional recovery was demonstrated in all five patients (follow-up score index 7.4 +/- 1.7). Six patients exhibited decreased perfusion but an abnormally high glucose to perfusion ratio (group 1B); their score index improved with dobutamine from 14.8 +/- 2.2 to 12 +/- 2.1 (p = 0.05), but late functional recovery was found in only one of the six patients (mean follow-up score index in group 1B 16 +/- 1.7). In the six remaining patients in whom no viable myocardium was detected with positron emission tomography (group 2), the echocardiographic score index did not change with dobutamine (15 +/- 0.9 to 14.7 +/- 0.8, p = NS) and there was no functional recovery (follow-up score index 15.5 +/- 1.0). Echocardiography during dobutamine infusion is a promising method to unmask viable myocardium in acute myocardial infarction. Early recovery of perfusion in the area at risk is associated with a good functional outcome, whereas a high glucose to perfusion ratio indicates jeopardized myocardium that frequently loses viability.