technetium-tc-99m-tetrofosmin and Arrhythmias--Cardiac

There are currently limited data on the relationships between resting perfusion abnormalities, left ventricular ejection fraction (LVEF), New York Heart Association (NYHA) functional class, and exercise capacity as defined by peak VO(2) and 6-minute walk test in patients with heart failure (HF) and reduced LVEF. Furthermore, the association between resting perfusion abnormalities and left ventricular dyssynchrony is currently unknown. This article addresses the Heart Failure and A Controlled Trial Investigating Outcomes of Exercise TraiNing (HF-ACTION) gated SPECT imaging (gSPECT) substudy baseline results.. HF-ACTION was a multicenter, randomized controlled trial of aerobic exercise training versus usual care in 2,331 stable patients with LVEF of < or = 35% and NYHA class II to IV HF symptoms treated with optimal medical therapy. Subjects enrolled in the HF-ACTION substudy underwent resting Tc-99m tetrofosmin gSPECT at baseline (n = 240). Images were evaluated for extent and severity of perfusion abnormalities using a 17-segment and a 5-degree gradation severity score (summed rest score [SRS]). Left ventricular function and dyssynchrony were assessed using validated available commercial software.. The average age of patients enrolled was 59, 69% were male, 63% were white, and 33% were African American. Of the 240 participants, 129 (54%) were ischemic and 111 (46%) were nonischemic in etiology. The median LVEF by gSPECT for the entire cohort was 26%. Among the nuclear variables, there was a modest correlation between LVEF and SRS (r = -0.31, P < .0001) and there were stronger correlations between phase SD and SRS (r = 0.66, P < .0001) as well as phase SD and LVEF (r = -0.50, P < .0001). Patients with NYHA class III symptoms had more severe and significant degrees of dyssynchrony (median phase SD 54 degrees ) than those with NYHA class II symptoms (median phase SD 39 degrees, P = .001). Patients with an ischemic etiology had a higher SRS (P < .0001) and significantly more dyssynchrony (P < .0001) than those who were nonischemic. However, there was no difference in LVEF or objective measures of exercise capacity between these groups. With respect to peak VO(2), there was a weak correlation with LVEF (r = 0.18, P = .006) and no correlation with SRS (r = -0.04, P = 0.59) or with dyssynchrony (r = -0.13, P = .09). A weak but statistically significant correlation between SRS and 6-minute walk was observed (r = -0.15, P = .047).. Gated SPECT imaging can provide important information in patients with HF due to severe LV dysfunction including quantitative measures of global systolic function, perfusion, and dyssynchrony. These measurements are modestly but significantly related to symptom severity and objective measures of exercise capacity.

Topics: Aged; Arrhythmias, Cardiac; Data Collection; Exercise Test; Exercise Therapy; Exercise Tolerance; Heart; Heart Failure; Heart Ventricles; Humans; Male; Middle Aged; Myocardial Perfusion Imaging; Organophosphorus Compounds; Organotechnetium Compounds; Stroke Volume; Tomography, Emission-Computed, Single-Photon; Ventricular Dysfunction, Left; Ventricular Function, Left

Disturbances of autonomic function after infarction are associated with both total mortality and sudden death. Although many imaging techniques for assessing the cardiac autonomic nervous system have been studied, the clinical usefulness of these techniques remains uncertain. This exploratory pilot study examined the relationship between abnormalities of ventricular sympathetic innervation delineated by scintigraphic imaging with (123)I-mIBG and inducible ventricular tachyarrhythmias in patients with left ventricular dysfunction and previous myocardial infarction.. Fifty patients underwent electrophysiological (EP) testing and 15-minute and 4-hour planar and single photon emission computed tomography (SPECT) imaging with (123)I-mIBG and SPECT imaging with (99m)Tc-tetrofosmin. The primary efficacy variables were the 4-hour heart:mediastinum ratio (H/M) and the (123)I-mIBG/(99m)Tc-tetrofosmin SPECT mismatch score. EP studies were categorized as positive (EP(+)) or negative (EP(-)) for inducibility of sustained (>30 seconds) ventricular tachyarrhythmias. Thirty patients were EP(+), and 20 were EP(-). There were no significant differences in the 4-hour H/M ratios or (123)I-mIBG/(99m)Tc-tetrofosmin SPECT mismatch scores between the two groups. In a multivariable analysis using all (123)I-mIBG and (99m)Tc-tetrofosmin SPECT measurements, the only variable that showed a significant difference between EP(+) and EP(-) patients was the 4-hour (123)I-mIBG SPECT defect score. A 4-hour (123)I-mIBG SPECT defect score of > or =37 yielded a sensitivity of 77% and specificity of 75% for predicting EP results.. The standard indices of (123)I-mIBG imaging (H/M and innervation-perfusion mismatch score) are not predictive of EP test results. The association of (123)I-mIBG SPECT defect severity with EP test inducibility in this exploratory study will require confirmation in a larger cohort of patients.

Topics: 3-Iodobenzylguanidine; Aged; Arrhythmias, Cardiac; Autonomic Nervous System; Electrophysiologic Techniques, Cardiac; Female; Heart; Humans; Iodine Radioisotopes; Male; Middle Aged; Myocardial Infarction; Organophosphorus Compounds; Organotechnetium Compounds; Positron-Emission Tomography; Radiopharmaceuticals; Sympathetic Nervous System; Tomography, Emission-Computed, Single-Photon; Ventricular Function, Left

471 patients had images adequate for total 17-segment scoring. There were 48 ArEs (10.2%). Neither. The presumption of a monotonic increase in ArE risk with increasing summed

Topics: 3-Iodobenzylguanidine; Arrhythmias, Cardiac; Causality; Comorbidity; Female; Heart Failure; Humans; Incidence; Internationality; Male; Middle Aged; Myocardial Ischemia; Organophosphorus Compounds; Organotechnetium Compounds; Prognosis; Radiopharmaceuticals; Reproducibility of Results; Risk Factors; Sensitivity and Specificity; Single Photon Emission Computed Tomography Computed Tomography; Survival Rate

Despite widespread prophylactic use of implantable cardioverter defibrillator (ICD) therapy, sudden cardiac death and refractory arrhythmia events are still important clinical issues to be overcome. We examined whether the impairment of cardiac sympathetic innervation and myocardial perfusion is responsible for lethal arrhythmic events and has prognostic value by comparing conventional clinical indices.. In consecutive ICDs implanted in 60 patients, cardiac uptake of (123)I-metaiodobenzylguanidine and (99m)Tc-tetrofosmin at rest was quantified, and then patients were prospectively followed with endpoints of appropriate ICD shocks or cardiac death. Cardiac metaiodobenzylguanidine activity was quantified as a heart-to-mediastinum ratio (HMR), and impaired tetrofosmin uptake was graded as a summed score (SS) using a computerized technique with a percentage of tracer uptake.. During a mean 29-mo interval, ICD shock was documented in 30 patients (50%); 3 cardiac deaths were also observed in this group of patients. Patients with ICD shocks had a significantly smaller HMR and a greater SS than did those without (1.73 +/- 0.34 vs. 2.06 +/- 0.46, P = 0.003, and 18.0 +/- 16.2 vs. 5.7 +/- 4.4, P = 0.001, respectively). Kaplan-Meier analysis showed that patients who had both an HMR of 1.90 or less and an SS of 12 or greater had a significantly greater ICD discharge rate than did those who had both an HMR greater than 1.90 and an SS less than 12 (94% vs. 18%, P < 0.005) (log rank, 15.14; P < 0.0005). Multivariate analysis with a Cox model identified the greatest Wald chi(2) of 6.454 and a hazard ratio of 3.857 (P = 0.011) when an HMR of 1.9 or less and tetrofosmin SS of 12 or greater were combined.. Impairment of cardiac sympathetic innervation and myocardial perfusion is related to lethal arrhythmic events leading to sudden death, and the combined assessment of these can identify patients for whom prophylactic ICD use has the greatest potential.

Topics: 3-Iodobenzylguanidine; Adult; Aged; Analysis of Variance; Arrhythmias, Cardiac; Coronary Circulation; Death, Sudden, Cardiac; Defibrillators, Implantable; Electrocardiography; Endpoint Determination; Female; Follow-Up Studies; Heart; Humans; Kaplan-Meier Estimate; Male; Middle Aged; Organophosphorus Compounds; Organotechnetium Compounds; Prognosis; Proportional Hazards Models; Radiopharmaceuticals; Sympathetic Nervous System; Tomography, Emission-Computed, Single-Photon

Failure to reach 80% of maximal predicted heart rate (HR) during exercise may render a myocardial perfusion single photon emission computed tomography (SPECT) study non-diagnostic for ischemia detection. We sought to investigate the injection of atropine in patients who fail to achieve 80% of age-predicted HR during exercise performed for myocardial perfusion SPECT (MPS), defining its safety and efficacy to raise HR to adequate levels as well as its effect on MPS interpretation.. Between January 2002 and December 2004, we studied 3,150 consecutive patients (2,253 men and 897 women, mean age 55 +/- 6 years) who were referred to a single office-based nuclear cardiology laboratory for MPS using SPECT imaging. One milligram of atropine was administered to patients that were unable to continue because of fatigue before reaching minimal HR, without an ischemic response (group A, n = 397). The scintigraphic results for group A were compared with those of patients who spontaneously achieved target HR (group B, n = 2,753). In group A, mean HR before atropine injection was 119.5 +/- 13.6 beats per minute (bpm), and it increased up to 137.3 +/- 13.5 bpm after drug administration, with an incremental of 17.8 +/- 6.9 bpm (P < 0.0001). The mean percentage of age-related HR achieved in this group was 83.5 +/- 8.1%. In 302 of this patients (76.1%) more than 80% of their aged-related HR (86.9 +/- 5.1%) was attained. No major adverse effects occurred. When groups A and B were compared, baseline and peak HR, rate pressure product, and maximal metabolic equivalents achieved were higher in group B. There were no significant differences in the percentage of total positive perfusion studies between both groups: 210/397 patients (52.9%) in group A and 1,342/2,753 patients (48.7%) in group B (P = 0.39). Ischemia or ischemia plus scar was found in 112/397 patients (28.2%) in group A and in 923/2,753 patients (33.5%) of group B (P = 0.14).. Atropine added to exercise stress testing in patients who cannot achieve their 80% age-related HR is a safe, well-tolerated, and feasible method for MPS.

Topics: Arrhythmias, Cardiac; Atropine; Blood Pressure; Cholinergic Antagonists; Coronary Circulation; Exercise Test; Feasibility Studies; Female; Heart Rate; Humans; Male; Middle Aged; Myocardial Ischemia; Organophosphorus Compounds; Organotechnetium Compounds; Radiopharmaceuticals; Research Design; Severity of Illness Index; Tomography, Emission-Computed, Single-Photon

Patients with permanent ventricular pacemakers (PP) are a difficult subgroup to assess in the study of coronary artery disease. The objective of this study was to evaluate the diagnostic value of the myocardial perfusion scintigraphy with 99mTC-Tetrofosmin (Tc-Tf) and stimulus with dipyridamole in patients with PP and suspected coronary artery disease.. Fourteen patients with suspected coronary artery disease and without structural cardiopathy, who underwent Tc-Tf and cardiac catheterization, were studied retrospectively. Sensitivity, specificity, predictive values and Kappa index were calculated for the diagnosis of coronary artery disease, multivessel disease, and for each one of the coronary arteries (left anterior descending, right coronary, and circumflex). In addition, the correlation between the number of territories with perfusion defects and the number of diseased vessels was studied.. In regards to the diagnosis of coronary artery disease, sensitivity, specificity, positive predictive value, negative predictive value and the Kappa index were 100%, 50%, 83%, 100% and 0.55, respectively. For multi-vessel disease, these values were 83%, 64%, 64%, 83% and 0.43 respectively. The correlation coefficient between the number of territories with perfusion defects and the number of diseased vessels was 0.61 (p = 0.02). In the diagnosis of anterior descending disease, sensitivity and specificity were 83% and 88% respectively. For the right coronary artery, these values were 100% and 44% and for the circumflex artery 38% and 83%, respectively.. In patients with PP and suspected coronary artery disease, myocardial perfusion scintigraphy with Tc-Tf and stimulus with dipyridamole is of great value in the diagnosis of coronary artery disease and in the assessment of its extension.

Topics: Aged; Aged, 80 and over; Angina Pectoris; Arrhythmias, Cardiac; Cardiac Catheterization; Comorbidity; Coronary Angiography; Coronary Circulation; Dipyridamole; Female; Humans; Male; Myocardial Infarction; Organophosphorus Compounds; Organotechnetium Compounds; Pacemaker, Artificial; Predictive Value of Tests; Radiopharmaceuticals; Risk Factors; Sensitivity and Specificity; Tomography, Emission-Computed, Single-Photon; Vasodilator Agents