Comparison of myocardial reperfusion in patients undergoing percutaneous coronary intervention in ST-segment elevation acute myocardial infarction with versus without diabetes mellitus (from the EMERALD Trial)

Diabetes mellitus is strongly associated with increased cardiovascular morbidity and mortality in patients with ST-segment elevation myocardial infarction. It is unknown whether myocardial perfusion is decreased in diabetic compared with nondiabetic patients after primary percutaneous coronary intervention (PCI), which may contribute to their worse prognosis. We compared myocardial perfusion and infarct sizes between diabetic and nondiabetic patients undergoing PCI for acute ST-segment elevation myocardial infarction in the EMERALD trial. EMERALD was a prospective, randomized, multicenter study evaluating distal embolic protection during primary PCI in ST-segment elevation myocardial infarction. End points included final myocardial blush grade, complete ST-segment resolution (STR) 30 minutes after PCI, and final infarct size as determined by technetium-99m single proton emission computed tomography measured between days 5 and 14. Of 501 patients, 62 (12%) had diabetes mellitus. Diabetic patients had impaired myocardial perfusion after PCI as measured by myocardial blush grade 0/1 (34% vs 16%, p = 0.002) and lower rates of complete 30-minute STR (45% vs 65%, p = 0.005). Infarct size (median 20% vs 11%, p = 0.005), development of new onset severe congestive heart failure (12% vs 4%, p = 0.016), and 30-day mortality (10% vs 1%, p <0.0001) were also greater in diabetic patients. After multivariate adjustment, diabetes remained associated with lack of complete STR and mortality at 6 months. Use of distal protection devices did not improve outcomes in diabetic or nondiabetic patients. In conclusion, in patients with ST-segment elevation myocardial infarction undergoing primary PCI, diabetes is independently associated with decreased myocardial reperfusion, larger infarct, development of congestive heart failure, and decreased survival.

Acute Myocardial Infarction With Hyperoxemic Therapy (AMIHOT)

OBJECTIVES

This study sought to determine whether hyperoxemic reperfusion with aqueous oxygen (AO) improves recovery of ventricular function after percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI).

BACKGROUND

Hyperbaric oxygen reduces myocardial injury and improves ventricular function when administered during ischemia-reperfusion.

METHODS

In a prospective, multicenter study, 269 patients with acute anterior or large inferior AMI undergoing primary or rescue PCI (<24 h from symptom onset) were randomly assigned after successful PCI to receive hyperoxemic reperfusion (treatment group) or normoxemic blood autoreperfusion (control group). Hyperoxemic reperfusion was performed for 90 min using intracoronary AO. The primary end points were final infarct size at 14 days, ST-segment resolution, and delta regional wall motion score index of the infarct zone at 3 months.

RESULTS

At 30 days, the incidence of major adverse cardiac events was similar between the control and AO groups (5.2% vs. 6.7%, p = 0.62). There was no significant difference in the incidence of the primary end points between the study groups. In post-hoc analysis, anterior AMI patients reperfused <6 h who were treated with AO had a greater improvement in regional wall motion (delta wall motion score index = 0.54 in control group vs. 0.75 in AO group, p = 0.03), smaller infarct size (23% of left ventricle in control group vs. 9% of left ventricle in AO group, p = 0.04), and improved ST-segment resolution compared with normoxemic controls.

CONCLUSIONS

Intracoronary hyperoxemic reperfusion was safe and well tolerated after PCI for AMI, but did not improve regional wall motion, ST-segment resolution, or final infarct size. A possible treatment effect was observed in anterior AMI patients reperfused <6 h of symptom onset.

Relationship and prognostic value of coronary artery calcification by electron beam computed tomography to stress-induced ischemia by single photon emission computed tomography

BACKGROUND

Stress single photon emission computed tomography (SPECT) is commonly performed in patients with abnormal electron beam computed tomography (EBCT) to define risk stratification, but the published prognostic data for patients undergoing both SPECT and EBCT are limited. The objective of the study was to examine the association and prognostic value between EBCT, coronary artery calcium score (CACS), and stress SPECT imaging.

METHODS

We identified 835 patients (age 54.8 +/- 10.0 years, 77% male) who underwent EBCT and stress SPECT within a 3-month period. Coronary artery calcium score was categorized as normal (0), minimal (1-10), mild (11-100), moderate (101-400), and severe (>400). Single photon emission computed tomography summed stress score (SSS) was categorized as normal, low risk, intermediate risk, and high risk per Cedar Sinai criteria. Average follow-up was 4.8 +/- 3.2 years. End points were all-cause death, death/myocardial infarction (MI), and death/MI/late revascularization.

RESULTS

The correlation of CACS to SSS was weak but statistically significant (r = +0.19, P < .001). The percentage of high-risk SSS increased with higher CACS scores; 4% of patients with normal EBCT and 18% with severe CACS had high-risk SSS. Coronary artery calcium score (chi2 = 11.4, P < .001), diabetes mellitus (chi2 = 4.6, P = .031), and chest pain class (chi2 = 8.7, P = .003) were independently associated with high-risk SPECT. The SSS (chi2 = 6.9, P = .009) and CACS (chi2 = 7.8, P = .005) were independently associated with mortality, as well as with both secondary end points of death/MI and death/MI/late revascularization. Only CACS predicted mortality in the 408 asymptomatic patients (chi2 = 5.2, P = .02), but these patients had an annual mortality of only 0.4% over the next 5 years.

CONCLUSIONS

In selected patients undergoing both EBCT and SPECT, CACS is weakly correlated with SPECT SSS, likely reflecting the different information provided by EBCT and SPECT. Coronary artery calcium score is independently associated with high-risk SPECT after adjustment for clinical variables. Coronary artery calcium score and SSS are complementary for the prediction of mortality in symptomatic patients. Only CACS predicted mortality in the asymptomatic patients, but they had a low annual mortality.

A normal stress SPECT scan is an effective gatekeeper for coronary angiography

BACKGROUND

The effectiveness of stress single photon emission computed tomography (SPECT) as a gatekeeper for coronary angiography has not been extensively investigated. The characteristics of patients referred for early angiography after a normal stress SPECT study have not been described.

METHODS AND RESULTS

Over a 10-year period, 14,273 patients without documented coronary artery disease (CAD) underwent stress SPECT. Images were abnormal in 47% and normal in 53%. The overall survival rate at 15 years was 55% for patients with abnormal images versus 71% for those with normal images (P < .001). Early coronary angiography (< or =3 months) was performed in only 97 patients (1.3%) with normal SPECT studies versus 1,756 patients (26%) with abnormal SPECT studies (P < .001). Most patients with normal SPECT studies referred for early angiography (85%) had clinical, exercise, or scintigraphic findings worrisome for CAD. Two thirds of these highly selected patients with normal SPECT studies who underwent angiography did not have significant CAD; the remaining one third had primarily 1- and 2-vessel CAD.

CONCLUSIONS

Stress SPECT is an effective gatekeeper for coronary angiography. The annual overall mortality rate for patients with normal images was 1.9%. Only 1.3% of patients with normal images were referred for early angiography.

Pathophysiological characteristics of heart rate recovery in heart failure

PURPOSE

Heart failure (HF) is associated with blunted HR recovery after exercise. The determinants of altered HR recovery in HF are unknown. The aim of this study was to investigate clinical correlates of HR recovery in HF patients.

METHODS

Echocardiography, pulmonary function tests, exercise testing, and neurohormonal measurements were performed in 98 HF patients. HR recovery was calculated as the difference between heart rate at peak exercise and at 1 min into a recovery period. Study subjects were divided into three groups based on HR recovery tertiles: group 1 (HR recovery < or = 6 bpm), group 2 (7 < or = HR recovery < or = 12), and group 3 (HR recovery > or = 13).

RESULTS

There were significant differences between the groups in multiple parameters. Compared with group 3, patients in group 1 had greater E/A ratios (1.81 +/- 0.26 vs 0.98 +/- 0.12, P = 0.011), shorter deceleration time (170 +/- 11 vs 223 +/- 11 ms, P = 0.016), and higher plasma atrial natriuretic peptide levels (207 +/- 32 vs 101 +/- 12 pg.mL, P = 0.008), indicating higher left ventricular filling pressures and elevated left atrial pressures. Pulmonary function tests were suggestive of greater restrictive changes in the lungs. Finally, subjects in group 1 had impaired exercise capacity, as evidenced by shorter exercise duration (5.2 +/- 0.2 vs 8.3 +/- 0.4 min, P < 0.001), lower peak VO2 (14.6 +/- 0.6 vs 22.2 +/- 1.0 mL.kg(-1).min(-1), P < 0.001), higher VE/VCO2 ratios (36.4 +/- 1.1 vs 31.1 +/- 0.9, P = 0.001), and reduced chronotropic responses to exercise (39 +/- 3 vs 69 +/- 4 bpm, P < 0.001).

CONCLUSION

HR recovery may be a clinically useful index identifying HF patients with distinct echocardiographic, neurohormonal, and hemodynamic characteristics. This may have implications for our understanding of the pathophysiology of impaired HR recovery in HF as well as for the clinical evaluation of such patients.

Differences in left ventricular ejection fraction and volumes measured at rest and poststress by gated sestamibi SPECT

BACKGROUND

Some studies suggested that the poststress left ventricle ejection fraction (LV EF) is lower than rest LV EF in patients with stress-induced ischemia.

METHODS AND RESULTS

By using a 2-day protocol and 30 mCi Tc-99m sestamibi, LV EF, end-systolic volume (ESV), and end-diastolic volume (EDV) were measured with gated SPECT. Of 99 eligible patients, 91 had technically adequate studies. Poststress LV EF minus rest LV EF was defined as DeltaLV EF. DeltaEDV and DeltaESV were similarly defined. Rest and poststress LV EF (r = 0.89), EDV (r = 0.78), and ESV (r = 0.93) were highly correlated (P <.001). Rest LV EF, EDV, and ESV were not significantly different between patients with and without stress-induced ischemia. DeltaLV EF was significantly lower in patients with stress-induced ischemia (-3.5% +/- 4.5% vs -1.1% +/- 4.7%, P = .02). Mean LV EF poststress in ischemic patients was 55.0% +/- 10.5% vs 61.2% +/- 10.0% in nonischemic patients (P = .008). However, only 1 patient (3%) with ischemia had DeltaLV EF that exceeded the 95% confidence limit of DeltaLV EF for normal patients. Ischemia was significantly associated with increased DeltaEDV and DeltaESV (P < .01).

CONCLUSIONS

Stress-induced ischemia is associated with poststress reduction in LV EF and increased poststress EDV and ESV. However, the effect of ischemia on the difference between poststress and rest EF measurements is modest and rarely exceeds the confidence limits in normal patients undergoing 2-day protocols. In most patients, poststress LV EF is an accurate reflection of rest LV EF.

The value of stress single photon emission computed tomography in patients without known coronary artery disease presenting with dyspnea

BACKGROUND

Dyspnea is a complex system with multiple etiologies, including myocardial ischemia ("anginal equivalent"). Few studies have examined the utility of stress testing to detect coronary artery disease in this setting. The purpose of this study was to examine the prevalence, severity, and prognostic value of perfusion defects detected by stress single photon emission computed tomography (SPECT) imaging in patients with dyspnea.

METHODS

SPECT imaging was performed in 1864 patients (age 65.8 +/- 10.2 years, 52% male, 23% diabetic, 89% overweight/obese) without known coronary artery disease referred for evaluation of dyspnea. Dyspnea was rated mild, moderate, or severe. SPECT scans were categorized low, intermediate, or high risk. The associations of stress SPECT imaging results with clinical variables and mortality were analyzed.

RESULTS

An abnormal perfusion SPECT image was present in 45% of patients and a high-risk scan in 11%. Male sex, diabetes, and clinical severity of dyspnea were the strongest predictors of both an abnormal and high-risk SPECT scan. A high-risk scan was present in 5% of nondiabetic women with mild dyspnea versus 22% of diabetic men with dyspnea of any severity. At 10 years, survival by SPECT scan category was low risk 75%, intermediate risk 68%, and high risk 53% (P < .001).

CONCLUSIONS

In this population of older overweight patients referred for evaluation of dyspnea, there was a high prevalence of abnormal (45%) and high-risk (11%) SPECT scans. High-risk scans were associated with much worse 10-year survival.

Reproducibility of measurements of regional myocardial blood flow in a model of coronary artery disease: Comparison of H215O and 13NH3 PET techniques

PET absolute myocardial blood flow (MBF) with H(2)15O and 13NH3 are widely used in clinical and research settings. However, their reproducibility with a 16-myocardial segment model has not been examined in chronic coronary artery disease (CAD). We examined the short-term reproducibility of PET H(2)15O MBF and PET 13NH3 MBF in an animal model of chronic CAD.

METHODS

Twelve swine (mean weight +/- SD, 38 +/- 5 kg) underwent percutaneous placement of a copper stent in the mid circumflex coronary artery, resulting in an intense inflammatory fibrotic reaction with luminal stenosis at 4 wk. Each animal underwent repeated resting MBF measurements by PET H(2)15O and PET 13NH3. Attenuation-corrected images were analyzed using commercial software to yield absolute MBF (mL/min/g) in 16 myocardial segments. MBF was also normalized to the rate.pressure product (RPP).

RESULTS

By Bland-Altman reproducibility plots, the mean difference was 0.01 +/- 0.18 mL/min/g and 0.01 +/- 0.11 mL/min/g, with confidence limits of +/-0.36 and +/-0.22 mL/min/g for uncorrected regional PET H(2)15O MBF and for uncorrected regional PET 13NH3 MBF, respectively. The repeatability coefficient ranged from 0.09 to 0.43 mL/min/g for H(2)15O and from 0.09 to 0.18 mL/min/g for 13NH3 regional MBF. RPP correction did not improve reproducibility for either PET H(2)15O or PET 13NH3 MBF. The mean difference in PET H(2)15O MBF was 0.03 +/- 0.14 mL/min/g and 0.02 +/- 0.19 mL/min/g for infarcted and remote regions, respectively, and in PET 13NH3 MBF was 0.03 +/- 0.11 mL/min/g and 0.00 +/- 0.09 mL/min/g for infarcted and remote regions, respectively.

CONCLUSION

PET H(2)15O and PET 13NH3 resting MBF showed excellent reproducibility in a closed-chest animal model of chronic CAD. Resting PET 13NH3 MBF was more reproducible than resting PET H(2)15O MBF. A high level of reproducibility was maintained in areas of lower flow with infarction for both isotopes.

Impact of time to therapy and reperfusion modality on the efficacy of adenosine in acute myocardial infarction: the AMISTAD-2 trial

AIMS

The purpose of this analysis was to determine whether the efficacy of adenosine vs. placebo was dependent on the timing of reperfusion therapy in the second Acute Myocardial Infarction Study of Adenosine (AMISTAD-II).

METHODS AND RESULTS

Patients presenting with ST-segment elevation anterior AMI were randomized to receive placebo vs. adenosine (50 or 70 microg/kg/min) for 3 h starting within 15 min of reperfusion therapy. In the present post hoc hypothesis generating study, the results were stratified according to the timing of reperfusion, i.e. > or = or < the median 3.17 h, and by reperfusion modality. In patients receiving reperfusion < 3.17 h, adenosine compared with placebo significantly reduced 1-month mortality (5.2 vs. 9.2%, respectively, P = 0.014), 6-month mortality (7.3 vs. 11.2%, P = 0.033), and the occurrence of the primary 6-month composite clinical endpoint of death, in-hospital CHF, or rehospitalization for CHF at 6 months (12.0 vs. 17.2%, P = 0.022). Patients reperfused beyond 3 h did not benefit from adenosine.

CONCLUSION

In this post hoc analysis, 3 h adenosine infusion administered as an adjunct to reperfusion therapy within the first 3.17 h onset of evolving anterior ST-segment elevation AMI enhanced early and late survival, and reduced the composite clinical endpoint of death or CHF at 6 months.

Effect of blinded peer review on abstract acceptance

CONTEXT

Peer review should evaluate the merit and quality of abstracts but may be biased by geographic location or institutional prestige. The effectiveness of blinded peer review at reducing bias is unknown.

OBJECTIVE

To evaluate the effect of blinded review on the association between abstract characteristics and likelihood of abstract acceptance at a national research meeting.

DESIGN AND SETTING

All abstracts submitted to the American Heart Association's annual Scientific Sessions research meeting from 2000-2004. Abstract review included the author's name and institution (open review) from 2000-2001, and this information was concealed (blinded review) from 2002-2004. Abstracts were categorized by country, primary language, institution prestige, author sex, and government and industry status.

MAIN OUTCOME MEASURE

Likelihood of abstract acceptance during open and blinded review, by abstract characteristics.

RESULTS

The mean number of abstracts submitted each year for evaluation was 13,455 and 28.5% were accepted. During open review, 40.8% of US and 22.6% of non-US abstracts were accepted (relative risk [RR], 1.81; 95% confidence interval [CI], 1.75-1.88), whereas during blinded review, 33.4% of US and 23.7% of non-US abstracts were accepted (RR, 1.41; 95% CI, 1.37-1.45; P<.001 for comparison between peer review periods). Among non-US abstracts, during open review, 31.1% from English- speaking countries and 20.9% from non-English-speaking countries were accepted (RR, 1.49; 95% CI, 1.39-1.59), whereas during blinded review, 28.8% and 22.8% of abstracts were accepted, respectively (RR, 1.26; 95% CI, 1.19-1.34; P<.001). Among abstracts from US academic institutions, during open review, 51.3% from highly prestigious and 32.6% from nonprestigious institutions were accepted (RR, 1.57; 95% CI, 1.48-1.67), whereas during blinded review, 38.8% and 29.0% of abstracts were accepted, respectively (RR, 1.34; 95% CI, 1.26-1.41; P<.001).

CONCLUSIONS

This study provides evidence of bias in the open review of abstracts, favoring authors from the United States, English-speaking countries outside the United States, and prestigious academic institutions. Moreover, blinded review at least partially reduced reviewer bias.

Improved survival in asymptomatic diabetic patients with high-risk SPECT imaging treated with coronary artery bypass grafting

BACKGROUND

The Bypass Angioplasty Revascularization Investigation trial demonstrated that symptomatic diabetics with multivessel coronary artery disease had a survival advantage with initial coronary artery bypass grafting (CABG) versus percutaneous coronary intervention (PCI). No published study has examined different treatments and outcome in asymptomatic diabetics.

METHODS AND RESULTS

This study group consisted of 826 asymptomatic diabetics (age 62+/-12 years; 76% men) without known coronary artery disease who had abnormal myocardial perfusion during stress single photon emission computed tomography (SPECT). SPECT images were classified as low-, intermediate-, and high-risk. Early revascularization (CABG or PCI < or =4 months after SPECT) was performed in 76 patients. Survival (follow-up, 5.3+/-3.3 years) was compared in patients treated with CABG, PCI, or medical therapy. Revascularization (CABG or PCI) was performed in 54 of 261 patients with high-risk scans and was independently associated with improved survival (chi2=4.55; P=0.03 after multivariate adjustment). Subset analysis demonstrated that the survival advantage was confined to patients treated with CABG (n=39), with a 5-year survival CABG at 85%, PCI at 72%, and medical therapy at 67% (P=0.02 for 3 groups). Although CABG was associated with better survival, mortality remained high (3% per year). There was no survival advantage by treatment for patients with less-severe SPECT abnormalities.

CONCLUSIONS

These nonrandomized data suggest that CABG improves survival in asymptomatic diabetic patients with high-risk SPECT, although revascularization was performed infrequently in these patients. These results parallel those of the Bypass Angioplasty Revascularization Investigation trial in symptomatic diabetic patients.

Prognostic utility of single-photon emission computed tomography in adult patients with hypertrophic cardiomyopathy

BACKGROUND

Data derived from stress myocardial perfusion imaging (MPI) carry prognostic significance in young patients with hypertrophic cardiomyopathy (HCM), but there are limited data on the utility of stress MPI in patients with HCM who are older. This study examined the prognostic significance of stress MPI in an adult population of patients with HCM.

METHODS

We examined 158 patients with HCM (aged 60 +/- 16 years, 61% men) who underwent exercise or pharmacologic stress MPI. Summed stress score (SSS, normal = 56) and summed reversibility scores were calculated for each patient. Follow-up was complete in 157 (99%) patients at a median duration of 5.2 years.

RESULTS

Normal single-photon emission computed tomography (SPECT) images were present in 38% of the population. Summed stress score (P = .01) and summed reversibility score (P = .03) were both significantly associated with cardiovascular death. Survival at 10 years was significantly better in those with normal versus abnormal SPECT (89% vs 67%, P = .04). Ten-year survival also was better in those without versus those with ischemia (90% vs 64%, P = .02). Five-year survival could be stratified by SSS risk categories: low risk (SSS > or = 53), 97%; intermediate risk (SSS = 48-52), 94%; and high risk (SSS < or = 47), 79% (P = .04). Bivariate models of SSS and other significant covariates supported an independent relation of SSS to cardiovascular death.

CONCLUSIONS

In an older population of patients with HCM referred for SPECT imaging, abnormal stress MPI identifies those at increased risk of cardiovascular death.

ACCF/ASNC appropriateness criteria for single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI): a report of the American College of Cardiology Foundation Quality Strategic Directions Committee Appropriateness Criteria Working Group and the American Society of Nuclear Cardiology endorsed by the American Heart Association

Under the auspices of the American College of Cardiology Foundation (ACCF) and the American Society of Nuclear Cardiology (ASNC), an appropriateness review was conducted for radionuclide cardiovascular imaging (RNI), specifically gated single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI). The review assessed the risks and benefits of the imaging test for several indications or clinical scenarios and scored them based on a scale of 1 to 9, where the upper range (7 to 9) implies that the test is generally acceptable and is a reasonable approach, and the lower range (1 to 3) implies that the test is generally not acceptable and is not a reasonable approach. The mid range (4 to 6) implies that the test may be generally acceptable and may be a reasonable approach for the indication. The indications for this review were primarily drawn from existing clinical practice guidelines and modified based on discussion by the ACCF Appropriateness Criteria Working Group and the Technical Panel members who rated the indications. The method for this review was based on the RAND/UCLA approach for evaluating appropriateness, which blends scientific evidence and practice experience. A modified Delphi technique was used to obtain first- and second-round ratings of 52 clinical indications. The ratings were done by a Technical Panel with diverse membership, including nuclear cardiologists, referring physicians (including an echocardiographer), health services researchers, and a payer (chief medical officer). These results are expected to have a significant impact on physician decision making and performance, reimbursement policy, and future research directions. Periodic assessment and updating of criteria will be undertaken as needed.