Effect of diabetes mellitus on myocardial 18F-FDG SPECT using acipimox for the assessment of myocardial viability

During the noninvasive assessment of myocardial viability with (18)F-FDG metabolic imaging, adequate regulation of metabolic conditions is needed to ensure optimal image quality. The aim of this study was to compare the feasibility and image quality of cardiac (18)F-FDG SPECT imaging using acipimox in patients with diabetes and patients without diabetes.

METHODS

Seventy patients with ischemic cardiomyopathy underwent (18)F-FDG SPECT using acipimox for the assessment of myocardial viability, followed by resting 2-dimensional echocardiography to identify dysfunctional myocardial tissue. The image quality was scored visually and quantitatively; the myocardium-to-background ratio was determined by region-of-interest analysis. The plasma concentrations of glucose and free fatty acids were determined to evaluate the metabolic conditions before and during (18)F-FDG imaging.

RESULTS

Thirty-four patients had diabetes mellitus; of these, 12 had insulin-dependent diabetes mellitus and 22 had non-insulin-dependent diabetes mellitus. The remaining 36 patients had no diabetes. During (18)F-FDG SPECT, no severe side effects occurred. Acipimox significantly lowered plasma levels of free fatty acids in both groups. Fifteen of 34 patients with diabetes had a plasma glucose level > 9 mmol/L, which was lowered successfully in all patients with additional insulin. Visual evaluation of the (18)F-FDG images showed good, moderate, and poor image quality in 27, 5, and 2 patients, respectively, with diabetes mellitus and in 32, 4, and 0 patients, respectively, without diabetes (P = not statistically significant). The myocardium-to-background ratio of (18)F-FDG SPECT images was comparable in patients with and without diabetes mellitus (3.1 +/- 1.0 vs. 3.5 +/- 0.9, P = not statistically significant). The type of diabetes had no influence on (18)F-FDG image quality.

CONCLUSION

(18)F-FDG SPECT metabolic imaging after acipimox is safe and practical for routine assessment of viability in patients with ischemic cardiomyopathy. Image quality is good, even in patients with diabetes, although additional insulin is sometimes needed.

Long-term prognosis after a normal exercise stress Tc-99m sestamibi SPECT study

BACKGROUND

Patients with a normal stress technetium 99m sestamibi study were shown to have a favorable outcome at intermediate-term follow-up. However, long-term survival has not been studied. The aim of this study was to evaluate the incidence and predictors of mortality and cardiac events at long-term follow-up after a normal exercise stress sestamibi study. Methods and results We studied 218 patients (mean age, 53 +/- 10 years, 108 men) who had normal myocardial perfusion assessed by Tc-99m sestamibi single photon emission computed tomography at rest and during symptom-limited bicycle exercise stress test. Endpoints during a follow-up period of 7.4 +/- 1.8 years were hard cardiac events (cardiac death and nonfatal myocardial infarction) and all-cause mortality. During follow-up, 13 patients died of various causes (cardiac death in 1 patient). Ten patients had nonfatal myocardial infarction (a total of 11 hard cardiac events). By multivariate analysis, independent predictors of cardiac events were history of coronary artery disease (chi(2) = 5, P =.03) and lower exercise heart rate (chi(2) = 12, P =.001). Independent predictors of all-cause mortality were age (chi(2) = 4, P =.05) and exercise heart rate (chi(2) = 5, P =.03). The annual mortality rate was 0.6% in the first 5 years and 1.8% between the sixth and eighth years. The annual hard cardiac event rate was 0.7% in the first 5 years and 1.5% between the sixth and eighth years. Receiver operating characteristic curves identified an exercise heart rate lower than 130 beats/min as the cutoff value that separated patients with regard to their risk for mortality and hard cardiac events.

CONCLUSIONS

It is concluded that the annual mortality and cardiac event rate is less than 1% during 5-year follow-up after a normal exercise sestamibi study. Therefore repeated testing would not be required unless there is a change in symptoms. Follow-up should be closer in patients with a history of coronary artery disease and in those who fail to achieve an exercise heart rate of 130 beats/min or greater.

Statins are associated with a reduced incidence of perioperative mortality in patients undergoing major noncardiac vascular surgery

BACKGROUND

Patients undergoing major vascular surgery are at increased risk of perioperative mortality due to underlying coronary artery disease. Inhibitors of the 3-hydroxy-3-methylglutaryl coenzyme A (statins) may reduce perioperative mortality through the improvement of lipid profile, but also through the stabilization of coronary plaques on the vascular wall.

METHODS AND RESULTS

To evaluate the association between statin use and perioperative mortality, we performed a case-controlled study among the 2816 patients who underwent major vascular surgery from 1991 to 2000 at the Erasmus Medical Center. Case subjects were all 160 (5.8%) patients who died during the hospital stay after surgery. From the remaining patients, 2 controls were selected for each case and were stratified according to calendar year and type of surgery. For cases and controls, information was obtained regarding statin use before surgery, the presence of cardiac risk factors, and the use of other cardiovascular medication. A vascular complication during the perioperative phase was the primary cause of death in 104 (65%) case subjects. Statin therapy was significantly less common in cases than in controls (8% versus 25%; P<0.001). The adjusted odds ratio for perioperative mortality among statin users as compared with nonusers was 0.22 (95% confidence interval 0.10 to 0.47). Similar results were obtained in subgroups of patients according to the use of cardiovascular therapy and the presence of cardiac risk factors.

CONCLUSIONS

This case-controlled study provides evidence that statin use reduces perioperative mortality in patients undergoing major vascular surgery.

Nuclear imaging is more sensitive for the detection of viable myocardium than dobutamine echocardiography

Intact perfusion, preserved metabolism of free fatty acids and glucose, and the presence of contractile reserve have been used as markers of viable myocardium. However, not all viable myocardium may exhibit all these characteristics. Accordingly, these features were evaluated in patients with chronic coronary artery disease and left ventricular dysfunction. Fourteen patients with chronic ischaemic heart disease and depressed left ventricular function (LVEF 34+/-10%) perfusion was evaluated by early resting 201Tl single photon emission computed tomography (SPECT), fatty acid utilization by 15-p-[123I]iodophenyl-3-(R,S)-methylpentadecanoic acid SPECT, glucose utilization by 2-[18F]fluoro-2-deoxy-D-glucose SPECT and contractile reserve (CR) by dobutamine echocardiography. The comparison of the different modalities was restricted to akinetic or dyskinetic myocardium as assessed by resting 2-dimensional echocardiography. For all techniques a 13-segment model was used. Sixty-four of 182 segments (35%) showed akinesia or dyskinesia. Intact perfusion was found in 33/64 (52%) segments. Fatty acid utilization was maintained in 38/64 (59%) segments and glucose utilization was maintained in 38/64 (59%) segments. CR was present in significantly fewer segments: 21 of 64 (33%) (P<0.01 vs glucose and fatty acid utilization). In the 21 segments with preserved CR, perfusion was intact in 16/21 (76%) segments, fatty acid utilization in 19/21 (90%) segments and glucose utilization was preserved in all (100%) segments. Conversely, in the 43 segments without CR, 17 segments (40%) showed intact perfusion, 19 segments (44%) preserved fatty acid utilization and 17 (40%) still showed preserved glucose utilization. Disagreement in segments between the viability markers was caused mainly by segments without CR but preserved perfusion, fatty acid or glucose utilization. The substantial number of segments with preserved glucose and fatty acid utilization but without contractile reserve, suggests an underestimation of myocardial viability by dobutamine echocardiography.

Prognostic value of dobutamine stress echocardiography in patients with diabetes

OBJECTIVE

The aim of this study was to assess the incremental value of dobutamine stress echocardiography (DSE) for the risk stratification of diabetic patients who are unable to perform an adequate exercise stress test. Exercise capacity is frequently impaired in patients with diabetes. The role of pharmacologic stress echocardiography in the risk stratification of diabetic patients has not been well defined.

RESEARCH DESIGN AND METHODS

We studied 396 diabetic patients (mean age 61 +/- 11 years, 252 men [64%]) with limited exercise capacity who underwent DSE for evaluation of known or suspected coronary artery disease (CAD). End points were hard cardiac events (cardiac death and nonfatal myocardial infarction) and all causes of mortality.

RESULTS

During a median follow-up of 3 years, 97 patients (24%) died (55 cardiac deaths), and 27 patients had nonfatal myocardial infarction. In an incremental multivariate analysis model, clinical predictors of hard cardiac events were history of congestive heart failure, previous myocardial infarction, hypercholesterolemia, and ejection fraction at rest. The percentage of ischemic segments was incremental to the clinical model in the prediction of hard cardiac events (chi(2) = 37 vs. 18, P < 0.05). Clinical predictors of all causes of mortality were history of congestive heart failure, age, hypercholesterolemia, and ejection fraction at rest. Wall motion score index at peak stress was incremental to the clinical model in the prediction of mortality (chi(2) = 52 vs. 43, P < 0.05).

CONCLUSIONS

DSE provides incremental data for the prediction of mortality and hard cardiac events in patients with diabetes who are unable to perform an adequate exercise stress test.

Hemodynamic response to lower body negative pressure in hemodialysis patients

BACKGROUND

Hypovolemia is thought to have an important role in the pathogenesis of dialysis-related hypotension.

METHODS

We studied the effect of hypovolemia simulated by lower body negative pressure (LBNP) in 11 hypotension-prone (HP) and 11 hypotension-resistant (HR) hemodialysis patients. LBNP was applied stepwise from 0 to -20 to -40 mm Hg. Systolic arterial pressure, heart rate, and central venous pressure (CVP) were recorded continuously after cannulation of the right jugular vein. Stroke volume index was measured at each step echocardiographically. At the end of each level of LBNP, blood samples were obtained to measure norepinephrine (NE), epinephrine (E), and atrial natriuretic peptide (ANP) levels.

RESULTS

At baseline, CVP (12 +/- 5 and 16 +/- 7 mm Hg), heart rate (72 +/- 9 and 70 +/- 13 beats/min), cardiac index (2.3 +/- 0.6 and 2.5 +/- 0.9 L/min), NE (median, 341 pg/mL [range,198 to 789 pg/mL] and 365 pg/mL [range, 177 to 675 pg/mL] or 2.02 nmol/L [range, 1.17 to 4.66 nmol/L] and 2.16 nmol/L [range, 1.05 to 4.00 nmol/L]), E (median, 46 pg/mL [range, 18 to 339 pg/mL] and 58 pg/mL [range, 21 to 122 pg/mL] or 251 pmol/L [range, 98 to 1,951 pmol/L] and 317 pmol/L [range, 115 to 666 pmol/L]) were similar, whereas systolic arterial pressure (141 +/- 26 versus 164 +/- 22 mm Hg) and ANP (median, 441 pg/mL [range, 152 to 1,330 pg/mL] versus 804 pg/mL [range, 517 to 3,560 pg/mL] ng/L) were lower (P < 0.05) in HP patients. In response to LBNP (-40 mm Hg), CVP decreased by 6.5 +/- 4.0 mm Hg in the HP group and 4.9 +/- 4.9 mm Hg in the HR group. In HP patients, this decrease was associated with a greater decrease in SI (37% +/- 16% versus 27% +/- 16%) and systolic arterial pressure (19% +/- 21% versus 4% +/- 14%) than in HR patients. Plasma ANP levels did not change, whereas increases in NE and E levels were similar in HP and HR patients.

CONCLUSION

Patients who frequently experience episodes of hypotension during dialysis also are prone to develop hypotension during LBNP, which results from reduced myocardial contractile reserve and/or inadequate sympathetic tone.

Acute myocardial infarction

Acute myocardial infarction is a common disease with serious consequences in mortality, morbidity, and cost to the society. Coronary atherosclerosis plays a pivotal part as the underlying substrate in many patients. In addition, a new definition of myocardial infarction has recently been introduced that has major implications from the epidemiological, societal, and patient points of view. The advent of coronary-care units and the results of randomised clinical trials on reperfusion therapy, lytic or percutaneous coronary intervention, and chronic medical treatment with various pharmacological agents have substantially changed the therapeutic approach, decreased in-hospital mortality, and improved the long-term outlook in survivors of the acute phase. New treatments will continue to emerge, but the greatest challenge will be to effectively implement preventive actions in all high-risk individuals and to expand delivery of acute treatment in a timely fashion for all eligible patients.

Incremental value of exercise technetium-99m tetrofosmin myocardial perfusion single-photon emission computed tomography for the prediction of cardiac events

Technetium-99m (Tc-99m) tetrofosmin single-photon emission computed tomography (SPECT) is a useful alternative to thallium-201 scintigraphy for the assessment of myocardial perfusion. This study assessed the incremental value of exercise Tc-99m tetrofosmin SPECT for the prediction of cardiac events in patients with known or suspected coronary artery disease. Exercise Tc-99m tetrofosmin SPECT imaging was performed in 655 consecutive patients. Follow-up was successful in 648 patients (98.9%). Ten patients underwent early coronary revascularization and were excluded. End points were cardiac death, nonfatal infarction, and late (>60 days) coronary revascularization. An abnormal study was defined as the presence of fixed and/or reversible perfusion defects. A summed stress score (SSS) was derived to estimate the extent and severity of perfusion defects. An abnormal scan was detected in 344 patients (54%). During a mean follow-up period of 4 +/- 1.3 years, 56 patients (9%) died (22 cardiac deaths). Nonfatal myocardial infarction occurred in 19 patients (3%), and 89 patients (14%) underwent late coronary revascularization. An abnormal scan was an independent predictor of cardiac death (hazard ratio 3.5, confidence intervals [CI] 1.1 to 12.2) and provided incremental information over clinical and exercise test data (log-likelihood -133 to -125, p <0.05). The SSS provided incremental prognostic information over clinical data as well (log-likelihood -133 to -127, p <0.05) (hazard ratio 1.23, CI 1.10 to 1.38). An abnormal scan (hazard ratio 3.3, CI 1.1 to 12.2)) and the SSS (hazard ratio 1.25, CI 1.07 to 1.45)) were powerful independent predictors of the combined end point of any cardiac event. Thus, exercise Tc-99m tetrofosmin myocardial perfusion SPECT provides information incremental to clinical data for the prediction of cardiac events in patients with known or suspected coronary artery disease.

Feasibility and image quality of dual-isotope SPECT using 18F-FDG and (99m)Tc-tetrofosmin after acipimox administration

Currently, with the rapidly increasing number of patients with heart failure due to chronic coronary artery disease, the need for viability studies to guide treatment in these patients is increasing. The most accurate method for viability assessment is metabolic imaging with (18)F-FDG with PET or SPECT. To obtain excellent image quality in all patients, the (18)F-FDG studies should be performed during hyperinsulinemic euglycemic clamping. However, this approach is time-consuming and is not feasible in busy nuclear medicine laboratories. Recently, the use of a nicotinic acid derivative, acipimox, has been suggested, but limited data are available on the image quality of the (18)F-FDG studies using this approach.

METHODS

We evaluated the feasibility and image quality of (18)F-FDG SPECT (with dual-isotope simultaneous acquisition (DISA) using (99m)Tc-tetrofosmin to assess perfusion) after acipimox administration in 50 nondiabetic patients. The image quality of both (18)F-FDG and (99m)Tc-tetrofosmin was assessed visually and quantitatively using myocardium-to-blood-pool (M/B) ratios as a measure of target-to-background ratio. The image quality and diagnostic value of DISA (99m)Tc-tetrofosmin SPECT was compared with standard (99m)Tc-tetrofosmin SPECT at baseline.

RESULTS

After acipimox administration, the plasma levels of free fatty acids were extremely low (68 +/- 89 nmol/L). No severe side effects were observed, only paroxysmal flushing. The (18)F-FDG image quality was good in 46 patients (92%) and moderate but still interpretable in the other 4 patients (8%). The clinical information of the baseline (99m)Tc-tetrofosmin SPECT was retained in the DISA (99m)Tc-tetrofosmin SPECT images because we did observe no substantial fill-in of perfusion defects by high (18)F-FDG uptake in the same segment.

CONCLUSION

Cardiac (18)F-FDG SPECT after acipimox is safe and resulted consistently in good image quality; this simple approach may be the method of choice for routine cardiac metabolic imaging.

Comparison of late outcome in patients with versus without angina pectoris having reversible perfusion abnormalities during dobutamine stress technetium-99m sestamibi single-photon emission computed tomography

The aim of this study was to assess the prognostic significance of reversible perfusion abnormalities in patients without angina during dobutamine stress technetium-99m sestamibi single-photon emission computed tomography (SPECT). The study comprised 224 patients (age 60 +/- 11 years, 144 men) with completely or partially reversible perfusion abnormalities during dobutamine stress sestamibi SPECT. Follow-up end points were hard cardiac events (cardiac death and nonfatal myocardial infarction). Angina occurred in 93 patients (42%) during the dobutamine stress test (symptomatic ischemia group). The 131 patients without dobutamine-induced angina represented the silent ischemia group. There was no significant difference between patients with and without angina with regard to summed stress perfusion score (5.3 +/- 2.5 vs 5.2 +/- 2.2, p = 0.9) or summed ischemic score (3.1 +/- 1.7 vs 3.2 +/- 1.4, p = 0.7). During a median follow-up of 7.2 years, cardiac death occurred in 14 patients (15%) with and in 21 patients (16%) without angina. Nonfatal myocardial infarction occurred in 8 patients (9%) with and in 13 patients (10%) without angina. In a multivariate analysis model of clinical and perfusion data, independent predictors of cardiac events were age (hazard ratio 1.02, confidence intervals [CI] 1.01 to 1.05 per year increment), diabetes mellitus (hazard ratio 1.9, CI 1.2 to 3.4), and ischemic perfusion score (hazard ratio 2.1, CI 1.3 to 3.8). Patients with silent ischemia defined as reversible perfusion abnormalities without associated angina during dobutamine stress sestamibi SPECT imaging had similar incidences of ischemia and similar cardiac event rates compared with patients with symptomatic ischemia. Therefore, the absence of angina in association with reversible perfusion abnormalities should not be interpreted as a sign of a more benign prognosis.

Dobutamine-induced contractile reserve in stunned, hibernating, and scarred myocardium in patients with ischemic cardiomyopathy

Because of damage to cardiomyocytes and the contractile apparatus, contractile reserve may be observed less frequently in hibernating than in stunned myocardium. The aim of this study was to assess the presence of contractile reserve in response to dobutamine infusion in a large group of patients with stunned and hibernating myocardium.

METHODS

A total of 198 consecutive patients with ischemic cardiomyopathy (left ventricular ejection fraction < or = 40%) underwent resting 2-dimensional echocardiography to assess regional contractile dysfunction. On the basis of assessment of perfusion (with (99m)Tc-tetrofosmin SPECT) and glucose use (with (18)F-FDG SPECT), dysfunctional segments were grouped. Dysfunctional segments with normal perfusion were classified as stunned. Dysfunctional segments with a perfusion defect were classified as hibernating when a perfusion-(18)F-FDG mismatch was present. Dysfunctional segments with a perfusion defect were classified as scar tissue when a perfusion-(18)F-FDG match was present; these segments were subdivided into nontransmural and transmural scars. Contractile reserve was evaluated by dobutamine stress echocardiography.

RESULTS

Dobutamine-induced contractile reserve was more frequently found in stunned than in hibernating myocardium (61% vs. 51%, respectively; P < 0.01). Only 14% of the scarred segments improved in wall motion during dobutamine infusion, significantly less than stunned or hibernating myocardium (P < 0.001). Nontransmural scars exhibited contractile reserve more frequently than did transmural scars.

CONCLUSION

The progressive reduction of contractile reserve in stunned, hibernating, and scarred myocardium supports the hypothesis that stunning, hibernation, and scarring are not circumscript pathophysiologic entities but represent gradual ultrastructural damage on the myocyte level.

Comparison between serum creatinine and creatinine clearance for the prediction of postoperative mortality in patients undergoing major vascular surgery

BACKGROUND

Poor renal function prior to surgery is associated with increased risk for mortality in patients undergoing major vascular surgery. Traditionally, this function is assessed by serum creatinine concentration (SeCreat). However, SeCreat is also influenced by age, gender and body weight. Hence, creatinine clearance (C(Cr)) is considered to be a better reflection of renal function. This study was undertaken to explore the prognostic value of preoperative calculated Cc, compared to SeCreat for the prediction of postoperative mortality.

PATIENTS AND METHODS

The study group comprised 852 consecutive patients who underwent elective major vascular surgery at the Erasmus Medical Center, Rotterdam. Preoperative C(Cr) was calculated based on the Cockroft-Gault equation using preoperative SeCreat, age, body weight and gender. Univariable logistic regression analyses were used to study the relation between preoperative SeCreat, C(Cr) and postoperative mortality. Furthermore, multivariable logistic regression analysis was applied to evaluate the additional predictive value of age, body weight and gender additional to SeCreat. The receiver operating characteristic (ROC) curve was determined to evaluate the predictive power of several regression models for perioperative mortality.

RESULTS

Postoperative mortality was 5.9% (50/852) within 30 days of surgery. In a univariable analysis, 10 micromol/l increment of SeCreat were associated with a 20% increased risk of postoperative mortality (OR = 1.2, 95% CI, 1.1-1.3) with an area under the ROC curve of 0.64 (95% CI, 0.56-0.71). If age, gender and body weight were added, the area under the ROC curve increased to 0.70 (95% CI, 0.63-0.77; p < 0.001), indicating that these risk factors had additional prognostic value. Indeed, in a separate regression analysis 10 ml/min decrease in C(Cr) was associated with a 40% increased risk of postoperative mortality (OR = 1.4,95% CI, 1.2-1.5; ROC area: 0.70, 95% CI, 0.63-0.76). ROC curve analysis showed that the cut-off value of 64 ml/min for C(Cr) yielded the highest sensitivity/specificity to predict postoperative mortality.

CONCLUSION

Preoperative SeCreat was strongly associated with postoperative mortality, and adding age, gender, and body weight to the model showed improved predictive power indicating that preoperative C(Cr) calculated with these data has additional prognostic value.

Validation of two risk models for perioperative mortality in patients undergoing elective abdominal aortic aneurysm surgery

The authors validated 2 clinical risk models for perioperative mortality in patients scheduled for elective open abdominal aortic aneurysm surgery (AAA surgery). They studied 361 patients who underwent elective AAA surgery between 1991 and 1999 (validation population). Two clinical risk models were validated. The first was developed in 238 patients from Leiden University Hospital (Leiden risk model). The Leiden risk model was modified to provide predictions for the validation population based on 6 predictors including age, gender, a history of previous myocardial infarction, congestive heart failure, renal disease, and pulmonary disease. The second was a recently published simpler risk model developed in 820 patients in the UK Small Aneurysm Trial (UK risk model) and included 3 predictors (age and renal and pulmonary comorbidity). Logistic regression was used to quantify the relationship between predictors and outcome (mortality within 30 days of surgery). Validation further included the concordance statistic (c-statistic) for discriminative ability and the Hosmer-Lemeshow test for model reliability. The perioperative mortality in the validation population was 6.6% (24/361). Predictors had similar odds ratios, with particularly strong effects of congestive heart failure, pulmonary disease, and renal impairment. The Leiden risk model had reasonable good ability (c-statistic 0.72) and showed adequate calibration (chi(2)=3.3, p=0.97). It could particularly identify a low-risk group. The UK risk model did not perform well (c-statistic 0.60), showing statistically significant lack of fit (chi(2)=64.9, p<0.001). This study showed similar predictive ability of previously identified predictors for perioperative mortality. The Leiden risk model could identify a low-risk group, while the UK risk model showed a relatively poor performance. The current study supports the use of the Leiden model for preoperative risk assessment.

Long-term prognostic value of dobutamine stress 99mTc-sestamibi SPECT: single-center experience with 8-year follow-up

PURPOSE

To determine the long-term prognostic value of dobutamine stress technetium 99m (99mTc)-labeled sestamibi single photon emission computed tomography (SPECT) in patients with limited exercise capacity.

MATERIALS AND METHODS

Clinical data and SPECT results were analyzed in 531 consecutive patients. Follow-up was successful in 528 (99.4%) patients; 55 underwent early revascularization and were excluded. Normal or abnormal findings were considered in the absence or presence of fixed and/or reversible perfusion defects. A summed stress score was calculated to estimate the extent and severity of perfusion defects. Univariate and multivariate Cox proportional hazards regression models were used to identify independent predictors of late cardiac events. The incremental value of myocardial perfusion scintigraphy over clinical variables in predicting events was determined according to two models. The probability of survival was calculated by using the Kaplan-Meier method.

RESULTS

Findings were abnormal in 312 patients. During 8.0 years +/- 1.5 of follow-up (range, 4.5-10.6 years), cardiac death occurred in 67 patients (total deaths, 165); nonfatal myocardial infarction, in 34; and late revascularization, in 49. The annual rates for cardiac death, cardiac death or infarction, and all events were 0.9%, 1.2%, and 1.5%, respectively, after normal findings and 2.7%, 3.4%, and 4.4%, respectively, after abnormal findings (P <.05). In a multivariable Cox proportional hazards model, not only an abnormal finding but also the summed stress score provided incremental prognostic information in addition to clinical data. The hazard ratio for cardiac death was 1.09 (95% CI: 1.01, 1.18) per 1-unit increment of the summed stress score.

CONCLUSION

The incremental prognostic value of dobutamine stress 99mTc-sestamibi SPECT over clinical data was maintained over an 8-year follow-up in patients with limited exercise capacity.

Non-compaction cardiomyopathy-echocardiographic diagnosis

Non-compaction cardiomyopathy is a recently recognized disorder caused by a defect in endomyocardial morphogenesis. The disease can present with heart failure, systemic embolic events, and ventricular arrhythmias. Long-term prognosis is poor. Echocardiography is used to confirm the diagnosis; in the current case-report, we describe the typical abnormalities observed on echocardiography in a patient with non-compaction cardiomyopathy.

Dobutamine stress myocardial perfusion imaging in coronary artery disease

The accurate noninvasive diagnosis and functional evaluation of coronary artery disease is an important step in selecting the appropriate management strategy. Dobutamine stress myocardial perfusion imaging is an alternative to exercise in patients with limited exercise capacity. In many centers, the test is performed on patients who have a contraindication for vasodilator stress testing. Recent studies have shown hyperemia induced by the standard dobutamine-atropine stress test is not less than hyperemia induced by dipyridamole. The feasibility of the test is 90% and is often higher in patients without beta-blocker therapy. The safety of the test has been well studied and was also demonstrated in specific patients groups, such as patients with left ventricular dysfunction, the elderly, and heart transplant recipients. The diagnostic accuracy has been demonstrated in patients with and without myocardial infarction and in specific groups such as those with hypertension, left ventricular hypertrophy, and heart transplant recipients and after revascularization. The technique has a high sensitivity for prediction of functional recovery in patients with myocardial dysfunction referred for revascularization. The presence and severity of myocardial perfusion abnormalities assessed by this method are powerful predictors of cardiac events, incremental to clinical data. This article describes the methodology, safety, feasibility, diagnostic accuracy, and prognostic value of dobutamine stress myocardial perfusion imaging in patients with known or suspected coronary artery disease, with additional considerations for the application of the test in specific patient groups.

Safety and feasibility of cardiac FDG SPECT following oral administration of Acipimox, a nicotinic acid derivative: Comparison of image quality with hyperinsulinemic euglycemic clamping in nondiabetic patients

BACKGROUND

Image quality of cardiac fluorine-18-deoxyglucose (FDG) studies is highly dependent on the metabolic conditions during the study; hyperinsulinemic euglycemic clamping ensures adequate image quality. However, the approach is time-consuming. Data in a small number of patients suggest that oral administration of a nicotinic acid derivative (Acipimox, 250 mg; Byk, The Netherlands) results in good image quality.

METHODS AND RESULTS

The safety and image quality of cardiac FDG single photon emission computed tomography studies after Acipimox administration were evaluated (21 patients, group 2); the results were compared with studies performed during hyperinsulinemic euglycemic clamping (69 patients, group 1). Image quality was assessed visually and quantitatively with use of heart-to-lung, heart-to-liver, and myocardium-to-background ratios. Blood samples were drawn at baseline and at the time of FDG injection to determine levels of glucose, free fatty acids, and insulin. Baseline characteristics of group 1 and 2 patients were comparable. No side effects occurred in group 1. Four patients in group 2 (19%) had paroxysmal flushing. Image quality, assessed visually, was good in 100% of group 1 patients and in 86% of group 2 patients. Images were uninterpretable in only 1 patient in group 2 (5%). All quantitative parameters of image quality (heart-to-lung, heart-to-liver, and myocardium-to-background ratios) were comparable between group 1 and 2 patients. Baseline plasma levels of all substrates were comparable between groups. At the time of FDG injection, plasma levels of glucose and free fatty acids were comparable between groups; insulin was higher in group 1 patients.

CONCLUSIONS

Cardiac FDG single photon emission computed tomography after Acipimox is a simple and safe approach that renders comparable image quality to that obtained during hyperinsulinemic euglycemic clamping.

Assessment of residual myocardial viability in regions with chronic electrocardiographic Q-wave infarction

BACKGROUND

Q waves on the electrocardiogram are often considered to be reflective of irreversibly scarred myocardium due to antecedent transmural myocardial infarction. However, there are some indications that residual viable tissue may be present in Q-wave-infarcted regions. It is clinically relevant to know how many Q-wave regions contain viable tissue because these patients may benefit from revascularization in terms of improvement of function and long-term survival.

METHODS

Patients (n = 150) with chronic electrocardiographic Q-wave infarction, heart failure symptoms, and chronic coronary artery disease underwent dobutamine-atropine stress echocardiography to assess myocardial viability. Residual viability in regions with Q-wave infarction was considered present when the end-diastolic wall thickness (EDWT) was >6 mm and the response during dobutamine infusion indicated viable tissue.

RESULTS

Baseline echocardiography revealed 517 dysfunctional myocardial regions; 202 of the dysfunctional regions were related to Q waves on the electrocardiogram and the other 315 dysfunctional regions were not. EDWT was < or =6 mm in 13 regions with a Q wave on the electrocardiogram, with only 1 region exhibiting viable tissue during dobutamine stress echocardiography. EDWT was >6 mm in 189 regions with a Q wave, with 118 (62%) having viable tissue on dobutamine stress echocardiography. In 6 dysfunctional regions without a Q wave, EDWT was < or =6 mm, with all being nonviable on dobutamine stress echocardiography; of the 309 regions without a Q wave and EDWT >6 mm, 204 (66%) exhibited viability on dobutamine stress echocardiography.

CONCLUSIONS

Fifty-eight percent of dysfunctional regions related to chronic Q waves were viable according to the combined information of EDWT and dobutamine stress echocardiography. EDWT </=6 mm virtually excludes viability; regions with EDWT >6 mm need additional testing to detect or exclude viability.

Left ventricular hypertrophy screening using a hand-held ultrasound device

AIMS

To test the diagnostic potential of a hand-held ultrasound device for screening for left ventricular hypertrophy in a hypertensive population using a standard echocardiographic system as a reference.

METHODS

One hundred consecutive hypertensive patients were enrolled. An experienced investigator performed measurements of the thickness of the anterior septum and posterior wall using the parasternal 2D-long axis view and the end-diastolic dimension of the left ventricle with both imaging devices. Left ventricular hypertrophy was defined as an increase in left ventricular mass > or = 134 g x m(-2) for men and > or = 110 g x m(-2) for women, when indexed for body surface area and > or = 143 g x m(-1) for men and > or = 102 g x m(-1) for women, when indexed for height.

RESULTS

Sixty-five men and 35 women were studied (age 60 +/- 11 years); mean duration of hypertension: 13 +/- 11 years; mean blood pressures: systolic 150 +/- 20 mmHg and diastolic 89 +/- 11 mmHg. The anterior septum and posterior wall were visualized in all patients with both imaging devices. The standard echocardiographic system identified left ventricular hypertrophy by body surface area in 18 (18%) patients and by height in 26 (26%) patients. The agreement between the standard echocardiographic system and the hand-held device for the assessment of left ventricular hypertrophy was 93%, kappa: 0.77 (left ventricular mass/body surface area) and 90%, kappa: 0.76 (left ventricular mass/height).

CONCLUSIONS

We conclude that hand-held devices can be effectively applied for screening for left ventricular hypertrophy in hypertensive patients.