Intensive medical therapy versus coronary angioplasty for suppression of myocardial ischemia in survivors of acute myocardial infarction: a prospective, randomized pilot study

Effects of Percutaneous Coronary Intervention on Death and Myocardial Infarction Stratified by Stable and Unstable Coronary Artery Disease: A Meta-Analysis of Randomized Controlled Trials

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In patients presenting with ST-segment–elevation myocardial infarction, percutaneous coronary intervention (PCI) reduces mortality when compared with fibrinolysis. In other forms of coronary artery disease (CAD), however, it has been controversial whether PCI reduces mortality. In this meta-analysis, we examine the benefits of PCI in (1) patients post–myocardial infarction (MI) who did not receive immediate revascularization; (2) patients who have undergone primary PCI for ST-segment–elevation myocardial infarction but have residual coronary lesions; (3) patients who have suffered a non–ST-segment–elevation acute coronary syndrome; and (4) patients with truly stable CAD with no recent infarct. This analysis includes data from the recently presented International Study of Comparative Health Effectiveness with Medical and Invasive Approaches (ISCHEMIA) and Complete versus Culprit-Only Revascularization Strategies to Treat Multivessel Disease after Early PCI for STEMI (COMPLETE) trials.

Impact of Follow-Up Ischemia on Myocardial Perfusion Single-Photon Emission Computed Tomography in Patients with Coronary Artery Disease

PURPOSE

Few studies have reported on predicting prognosis using myocardial perfusion single-photon emission computed tomography (SPECT) during coronary artery disease (CAD) treatment. Therefore, we aimed to assess the clinical implications of myocardial perfusion SPECT during follow-up for CAD treatment.

MATERIALS AND METHODS

We enrolled 1153 patients who had abnormal results at index SPECT and underwent follow-up SPECT at intervals ≥6 months. Major adverse cardiac events (MACE) were compared in overall and 346 patient pairs after propensity-score (PS) matching.

RESULTS

Abnormal SPECT was associated with a significantly higher risk of MACE in comparison with normal SPECT over the median of 6.3 years (32.3% vs. 19.8%; unadjusted p<0.001). After PS matching, abnormal SPECT posed a higher risk of MACE [32.1% vs. 19.1%; adjusted hazard ratio (HR)=1.73; 95% confidence interval (CI)=1.27-2.34; p<0.001] than normal SPECT. After PS matching, the risk of MACE was still higher in patients with abnormal follow-up SPECT in the revascularization group (30.2% vs. 17.9%; adjusted HR=1.73; 95% CI=1.15-2.59; p=0.008). Low ejection fraction [odds ratio (OR)=5.33; 95% CI=3.39-8.37; p<0.001] and medical treatment (OR=2.68; 95% CI=1.93-3.72; p<0.001) were independent clinical predictors of having an abnormal result on follow-up SPECT.

CONCLUSION

Abnormal follow-up SPECT appears to be associated with a high risk of MACE during CAD treatment. Follow-up SPECT may play a potential role in identifying patients at high cardiovascular risk.

Effect of changes in perfusion defect size during serial regadenoson myocardial perfusion imaging on cardiovascular outcomes in high-risk patients

BACKGROUND

The prognostic value of single-photon emission computed tomography myocardial perfusion imaging (MPI) is well established. There is a paucity of data on the prognostic value of changes in perfusion defect size (PDS) on serial MPIs.

METHODS

From the MPI database at the University of Alabama at Birmingham, consecutive patients who underwent two regadenoson stress MPIs between July 2008 and March 2013 were identified. The MPIs were analyzed side-by-side using an automated software program for presence and change in PDS. Improvement in PDS was defined as a reduction ≥5% of left ventricle. A drop in left ventricular ejection fraction (LVEF) was defined as a decrease ≥5%. The primary outcome was a composite of death, myocardial infarction (MI), and coronary revascularization (CR).

RESULTS

There were 698 patients (61 ± 11 years, 53% male, 48% diabetes, 25% prior MI, 49% prior CR) who underwent two regadenoson MPIs within 16 ± 9 months for clinical indications. The primary outcome occurred in 167 (24%) patients (8% death, 9% MI, 15% CR) during 24 ± 16 months of follow-up after the second MPI. The MPIs were normal in both studies in 399 (57%, Group 1), showed improvement in 94 (14%, Group 2, PDS 15% ± 16% vs 28% ± 18%, P < .001) and no change or worsening in 205 patients (29%, Group 3, 28% ± 17% vs 20% ± 17%, P < .001). The best outcomes were seen in Group 1 and the worst in Group 3 (log-rank P < .001). Similar trends were seen for the components of the primary outcome (P = .04 for death, P < .001 for MI, P < .001 for CR). In a Cox-regression model that adjusted for baseline factors including PDS and LVEF on initial MPI, the hazard ratios for primary outcome were 2.0 (P = .02) and 3.9 (P < .001) for Groups 2 and 3 compared to Group 1, respectively. In addition, an LVEF drop ≥5% was independently associated with the primary outcome (HR 1.5, P = .01).

CONCLUSION

Changes in PDS and LVEF on serial MPIs provide incremental prognostic information to initial and follow-up MPI findings. Lack of improvement or an increase in PDS and a drop in LVEF identify high-risk patients.

Who is eligible for randomized trials? A comparison between the exclusion criteria defined by the ISCHEMIA trial and 3102 real-world patients with stable coronary artery disease undergoing stent implantation in a single cardiology center

BACKGROUND

Randomized controlled trials are the gold standard for evaluating therapy; however, controversy exists regarding the applicability of such results to daily practice, as patients are often pre-selected and may not reflect real-world clinical settings. We studied the eligibility criteria for 3102 "real-life" patients with stable coronary artery disease (SCAD) according to the ISCHEMIA (International Study of Comparative Health Effectiveness with Medical and Invasive Approaches) trial exclusion criteria. The aim of our analysis was to estimate the percentage of real-life patients who would have met the exclusion criteria for the ISCHEMIA trial.

METHODS

We analyzed 3102 patients with SCAD referred to the Silesian Center for Heart Disease who underwent both coronary angiography and stent implantation between January 2006 and December 2011. The patients were divided into two groups. Group A was composed of patients with SCAD who would have been excluded from the ongoing ISCHEMIA trial, whereas group B represented the remaining patients.

RESULTS

A total of 1900 (61.3%) patients met at least one of the exclusion criteria. The most frequent exclusion criterion noted was revascularization within the previous 12 months (938 patients; 49.4%), followed by unacceptable level of angina symptoms (532 patients; 28 %), low ejection fraction (467 patients; 24.6%), and acute coronary syndrome within the previous 2 months (456 patients; 24%). Patients from our cohort who would have been excluded from the ISCHEMIA trial were older, had more comorbidities, and experienced worse long-term outcomes.

CONCLUSIONS

The ISCHEMIA trial exclusion criteria ruled out the majority of the patients with SCAD undergoing percutaneous coronary intervention in "real life". Our cohort of patients who would have been excluded from the ISCHEMIA trial had more comorbidities and experienced significantly worse long-term outcomes than patients who did not meet the ISCHEMIA trial exclusion criteria.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01471522.

Ischaemia change with revascularisation versus medical therapy in reduced ejection fraction

Objective

Nuclear imaging data demonstrate that revascularisation leads to favourable effects on ischaemia burden and improved outcomes compared with medical therapy (MT). In patients with heart failure (HF), the effects of MT versus revascularisation on ischaemia change and its independent prognostic significance requires investigation.

Methods

From the Duke Databank, we performed a retrospective analysis of 278 consecutive patients with coronary artery disease (CAD) and ejection fraction (EF) ≤40%, who underwent 2 serial myocardial perfusion scans between 1993 and 2009. Ischaemia change was calculated for patients undergoing MT alone, or revascularisation. Cox proportional hazards regression modelling was used to identify factors associated with death/myocardial infarction (MI).

Results

The magnitude of ischeamia reduction was greater with revascularisation than with MT alone (median change of −6% vs 0%, p<0.001). With revascularisation, more patients experienced ≥5% ischaemia reduction compared with MT (52% vs 25%, p<0.01) and a similar percentage experienced ≥5% ischaemia worsening (13% vs 18%, p=0.37). After risk adjustment, ≥5% ischaemia worsening was associated with decreased death/MI (HR=0.58; 95% CI 0.36 to 0.96).

Conclusions

In patients with HF with CAD, revascularisation improves long-term ischaemia burden compared with MT. Ischaemia worsening on nuclear imaging was associated with reduced risk of death/MI, potentially related to development of ischaemic viable myocardium as opposed to scar tissue.

Serial myocardial perfusion imaging: defining a significant change and targeting management decisions

Myocardial perfusion imaging (MPI) with gated single-photon emission tomography provides important information on the extent and severity of myocardial perfusion abnormalities, including myocardial ischemia. The availability of software for automated quantitative assessment of myocardial perfusion in an objective and more reproducible manner than visual assessment has allowed MPI to be particularly effective in serial evaluation. Serial testing using MPI is widely used in guiding patient care despite the lack of well-defined appropriateness use criteria. This should not be surprising because ischemic heart disease is a life-long malady subject to dynamic changes throughout its natural course and particularly following man-made interventions that may improve or worsen the disease process, such as medical therapy and coronary revascularization. Serial MPI has filled an important clinical gap by providing crucial information for managing patients with changes in clinical presentations or in anticipation of such changes in patients with stable symptoms. In the research arena, serial MPI has been widely applied in randomized controlled trials to study the impact of various medical and interventional therapies on myocardial perfusion, as well as the relative merits of new imaging procedures (hardware and/or software), radiotracers, and stressor agents. Serial testing, however, unlike initial or 1-time testing, has more stringent requirements and is subject to variability because of technical, procedural, interpretational, and biological factors. The intrinsic variability of MPI becomes important in interpreting serial tests in order to define a true change in a given patient and to guide clinical decision making. The purpose of this first comprehensive review on this subject is to illustrate where serial MPI may be useful clinically and in research studies, and to highlight strategies for addressing the various issues that are unique to serial testing in order to derive more valid and robust data from the serial scans.

Ischemia change in stable coronary artery disease is an independent predictor of death and myocardial infarction

OBJECTIVES

The aim of this study was to evaluate the independent prognostic significance of ischemia change in stable coronary artery disease (CAD).

BACKGROUND

Recent randomized trials in stable CAD have suggested that revascularization does not improve outcomes compared with optimal medical therapy (MT). In contrast, the nuclear substudy of the COURAGE (Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation) trial found that revascularization led to greater ischemia reduction and suggested that this may be associated with improved unadjusted outcomes. Thus, the effects of MT versus revascularization on ischemia change and its independent prognostic significance requires further investigation.

METHODS

From the Duke Cardiovascular Disease and Nuclear Cardiology Databanks, 1,425 consecutive patients with angiographically documented CAD who underwent 2 serial myocardial perfusion single-photon emission computed tomography scans were identified. Ischemia change was calculated for patients undergoing MT alone, percutaneous coronary intervention, or coronary artery bypass grafting. Patients were followed for a median of 5.8 years after the second myocardial perfusion scan. Cox proportional hazards regression modeling was used to identify factors independently associated with the primary outcome of death or myocardial infarction (MI). Formal risk reclassification analyses were conducted to assess whether the addition of ischemia change to traditional predictors resulted in improved risk classification for death or MI.

RESULTS

More MT patients (15.6%) developed ≥5% ischemia worsening compared with those undergoing percutaneous coronary intervention (6.2%) or coronary artery bypass grafting (6.7%) (p < 0.001). After adjustment for established predictors, ≥5% ischemia worsening remained a significant independent predictor of death or MI (hazard ratio: 1.634; p = 0.0019) irrespective of treatment arm. Inclusion of ≥5% ischemia worsening in this model resulted in significant improvement in risk classification (net reclassification improvement: 4.6%, p = 0.0056) and model discrimination (integrated discrimination improvement: 0.0062, p = 0.0057).

CONCLUSIONS

In stable CAD, ischemia worsening is an independent predictor of death or MI, resulting in significantly improved risk reclassification when added to previously known predictors.

A meta-analysis of randomized controlled trials comparing percutaneous coronary intervention with medical therapy in stable angina pectoris

There continues to remain uncertainty regarding the effect of percutaneous coronary intervention (PCI) vs medical therapy in patients with stable angina. We therefore performed a systematic review and study-level meta-analysis of randomized controlled trials of patients with stable angina comparing PCI vs medical therapy for each of the following individual outcomes: all-cause mortality, cardiovascular (CV) mortality, myocardial infarction (MI), and angina relief. We used 8 strategies to identify eligible trials including bibliographic database searches of MEDLINE, PubMed, EMBASE, and the Cochrane Controlled Trials Registry until November 2011. Two independent reviewers undertook decisions about study eligibility and data abstraction. Data were pooled using a random effects model. Ten prospective randomized controlled trials fulfilled our eligibility criteria and they included a total of 6752 patients. We did not detect differences between PCI vs medical therapy for all-cause mortality (663 events; relative risk [RR], 0.97 [confidence interval (CI), 0.84-1.12]; I(2) = 0%), CV mortality (214 events; RR, 0.91 [CI, 0.70-1.17]; I(2) = 0%), MI (472 events; RR, 1.09 [CI, 0.92-1.29]; I(2) = 0%), or angina relief at the end of follow-up (2016 events; RR, 1.10 [CI, 0.97-1.26]; I(2)=85%). PCI was not associated with reductions in all-cause or CV mortality, MI, or angina relief. Considering the cost implication and the lack of clear clinical benefit, these findings continue to support existing clinical practice guidelines that medical therapy be considered the most appropriate initial clinical management for patients with stable angina.

Importance of residual myocardial ischemia after intervention in the genesis of cardiovascular events among patients with chronic coronary artery disease

Recent randomized clinical trials support the strategy of ischemia-guided management for patients with stable ischemic heart disease. The application of serial testing to examine the efficacy of therapeutic intervention for ischemia suppression and to document the extent and severity of ischemia provides an important means to guide clinical decision making. This review provides a synopsis of available evidence on serial testing and meaningful thresholds for application of paired rest/stress myocardial perfusion single photon emission computed tomography imaging.

Percutaneous coronary intervention in chronic stable angina

Although the therapeutic advantage of percutaneous coronary intervention in acute coronary syndromes have been proved in numerous studies, its position in the treatment of stable angina remains a controversial issue. The results of the recent studies did not lead into definite answers for the proper treatment of chronic coronary artery disease. The identification of the patients that will benefit from the interventional approach is necessary and is probably based on the proper screening for myocardial ischemia with noninvasive diagnostic techniques. In this review article, we mention the most recent studies for the treatment of chronic stable angina with respect to clinical outcome and economical consequences.

Predicting clinically unrecognized coronary artery disease: use of two- dimensional echocardiography

BACKGROUND

2-D Echo is often performed in patients without history of coronary artery disease (CAD). We sought to determine echo features predictive of CAD.

METHODS

2-D Echo of 328 patients without known CAD performed within one year prior to stress myocardial SPECT and angiography were reviewed. Echo features examined were left ventricular and atrial enlargement, LV hypertrophy, wall motion abnormality (WMA), LV ejection fraction (EF) < 50%, mitral annular calcification (MAC) and aortic sclerosis/stenosis (AS). High risk myocardial perfusion abnormality (MPA) was defined as >15% LV perfusion defect or multivessel distribution. Severe coronary artery stenosis (CAS) was defined as left main, 3 VD or 2VD involving proximal LAD.

RESULTS

The mean age was 62 +/- 13 years, 59% men, 29% diabetic (DM) and 148 (45%) had > 2 risk factors. Pharmacologic stress was performed in 109 patients (33%). MPA was present in 200 pts (60%) of which, 137 were high risk. CAS was present in 166 pts (51%), 75 were severe. Of 87 patients with WMA, 83% had MPA and 78% had CAS. Multivariate analysis identified age >65, male, inability to exercise, DM, WMA, MAC and AS as independent predictors of MPA and CAS. Independent predictors of high risk MPA and severe CAS were age, DM, inability to exercise and WMA. 2-D echo findings offered incremental value over clinical information in predicting CAD by angiography. (Chi square: 360 vs. 320 p = 0.02).

CONCLUSION

2-D Echo was valuable in predicting presence of physiological and anatomical CAD in addition to clinical information.

The impact of revascularization on mortality in patients with nonacute coronary artery disease

BACKGROUND

Although early revascularization improves outcomes for patients with acute coronary syndromes, the role of revascularization for patients with nonacute coronary artery disease is controversial. The objective of this meta-analysis was to compare surgical or percutaneous revascularization with medical therapy alone to determine the impact of revascularization on death and nonfatal myocardial infarction in patients with coronary artery disease.

METHODS

The Medline and Cochrane Central Register of Controlled Trials databases were searched to identify randomized trials of coronary revascularization (either surgical or percutaneous) versus medical therapy alone in patients with nonacute coronary disease reporting the individual outcomes of death or nonfatal myocardial infarction reported at a minimum follow-up of 1 year. A random effects model was used to calculate odds ratios (OR) for the 2 prespecified outcomes.

RESULTS

Twenty-eight studies published from 1977 to 2007 were identified for inclusion in the analysis; the revascularization modality was percutaneous coronary intervention in 17 studies, coronary bypass grafting in 6 studies, and either strategy in 5 studies. Follow-up ranged from 1 to 10 years with a median of 3 years. The 28 trials enrolled 13,121 patients, of whom 6476 were randomized to revascularization and 6645 were randomized to medical therapy alone. The OR for revascularization versus medical therapy for mortality was 0.74 (95% confidence interval [CI], 0.63-0.88). A stratified analysis according to revascularization mode revealed both bypass grafting (OR 0.62; 95% CI, 0.50-0.77) and percutaneous intervention (OR 0.82; 95% CI, 0.68-0.99) to be superior to medical therapy with respect to mortality. Revascularization was not associated with a significant reduction in nonfatal myocardial infarction compared with medical therapy (OR 0.91; 95% CI, 0.72-1.15).

CONCLUSION

Revascularization by coronary bypass surgery or percutaneous intervention in conjunction with medical therapy in patients with nonacute coronary artery disease is associated with significantly improved survival compared with medical therapy alone.

A meta-analysis of 17 randomized trials of a percutaneous coronary intervention-based strategy in patients with stable coronary artery disease

OBJECTIVES

This study assessed the impact on long-term mortality of percutaneous coronary intervention (PCI) versus medical treatment in patients with symptoms or signs of myocardial ischemia but no acute coronary syndrome.

BACKGROUND

The impact of PCI on the long-term prognosis of patients with stable coronary artery disease has not been established.

METHODS

We identified 17 randomized trials comparing a PCI-based invasive treatment strategy with medical treatment in 7,513 patients with symptoms or signs of myocardial ischemia but no acute coronary syndrome. Of these patients, 3,675 were assigned to the PCI group and 3,838 to the medical treatment group. The primary end point was all-cause death. The length of follow-up was in the range between 12 and 122 months, 51 months on average.

RESULTS

In the PCI group, 271 patients died compared with 335 patients in the medical treatment group, which corresponds to a 20% reduction in the odds ratio (OR) of all-cause death (OR: 0.80; 95% confidence interval [CI]: 0.64 to 0.99, p = 0.263 for heterogeneity across the trials). Allocation to the PCI group was associated with a nonsignificant 26% reduction in the OR of cardiac death (OR: 0.74, 95% CI: 0.51 to 1.06). In the PCI group, 319 patients had a nonfatal myocardial infarction after randomization compared with 357 patients in the medical treatment group (OR: 0.90, 95% CI: 0.66 to 1.23).

CONCLUSIONS

These findings suggest that a PCI-based invasive strategy may improve long-term survival compared with a medical treatment-only strategy in patients with stable coronary artery disease.

Combining myocardial perfusion imaging with computed tomography for diagnosis of coronary artery disease

PURPOSE OF REVIEW

To illustrate where the integration of computed tomography with myocardial perfusion single photon tomography may improve current diagnostic imaging paradigms and allow for enhanced risk stratification.

RECENT FINDINGS

Computed tomography has the advantage of detecting coronary atherosclerosis at its earliest stages and also identifying patients at high risk for having underlying myocardial ischemia, allowing initiation of appropriate therapeutic measures well before development of obstructive coronary artery disease. Single photon computed tomography can, conversely, clarify the anatomic findings of computed tomography, based on a functional assessment of myocardial blood flow, thereby guiding antiischemic and interventional therapies.

SUMMARY

Hybrid imaging with single photon tomography and computed tomography angiography may prove important from a diagnostic and therapeutic viewpoint in several clinical scenarios. It is likely that fusion imaging may more precisely tailor therapy, reduce healthcare costs and improve patient outcome over the next decade.

Adenosine single photon emission computed tomography for assessing risk after myocardial infarction: recent developments

PURPOSE OF REVIEW

While the prognostic power of adenosine single photon emission computed tomography myocardial perfusion imaging has been validated in multiple patient populations including those with known or suspected coronary artery disease, the utility of this modality in assessing risk after an acute myocardial infarction in the primary angioplasty era is still a topic of debate.

RECENT FINDINGS

The INSPIRE trial showed that early adenosine single photon emission computed tomography myocardial perfusion imaging is capable of identifying low-risk patients for early hospital discharge after acute myocardial infarction. This novel study demonstrated that intensive medical therapy is a reasonable strategy in low, intermediate, and high-risk post-myocardial infarction patients with preserved left ventricular function.

SUMMARY

The INSPIRE trial established the role for early adenosine single photon emission computed tomography myocardial perfusion imaging as a tool for risk stratification in stable patients after an acute myocardial infarction and provided evidence that intensive medical therapy is comparable to coronary revascularization in suppressing ischemia and presumably improving cardiac outcomes. It remains to be seen whether these new findings will alter current American College of Cardiology/American Heart Association guidelines, which emphasize a primary role of coronary revascularization in acute coronary syndromes.

Gated SPECT imaging to detect changes in myocardial blood flow during progressive coronary occlusion

BACKGROUND

The ability to track dynamic changes in myocardial blood flow (MBF) and wall motion with serial gated perfusion imaging may be a limiting factor in assessing new therapies. The purpose of this study was to determine whether gated Tc-99 m sestamibi (MIBI) SPECT imaging can track small changes in MBF in a model of progressive ischemia.

METHODS

Eight pigs (20 kg) underwent lateral thoracotomy for placement of an ameroid constrictor on the left circumflex coronary artery (LCX) and indwelling femoral and left atrial catheters for serial microsphere determinations of absolute MBF. Animals underwent concurrent left atrial microsphere and Tc-99 m sestamibi (0.3 mCi/Kg IV) injections at weekly intervals over 6 weeks per animal. Gated SPECT imaging was acquired for each injection using high resolution collimation and standard processing. The animals were sacrificed on day 42. Mean signal intensity (SI) from regions of interest (ROI) corresponding to control and ischemic MBF by microspheres was measured for three SPECT short-axis images. Mean contrast ratio (MCR) was calculated from the ratio of ischemic to control SI per slice. Regional wall motion (RWM) from gated images was scored 1-5 using a 16 segment model and a score index (RWMI) was calculated.

RESULTS

MBF decreased progressively (27% below resting values [P < 0.0001]) but with a clear and significant partial recovery by day 42 (13% improvement from peak ischemia, [P < 0.01]). SPECT perfusion and gated RWM closely paralleled the dynamic pattern of MBF caused by the ameroid constrictor. SPECT MCR decreased 21% from baseline scans in the LCX territory (P < 0.0001) and improved 11% from peak ischemia (P < 0.01) while the gated RWMI (1.0 at baseline) peaked at 1.36 and improved to 1.13 by day 42.

CONCLUSION

Gated SPECT-a technique readily available-tracks dynamic changes in MBF closely with both perfusion and RWM. For trials of new therapies for the alleviation of chronic ischemia, these findings have direct implications for measuring efficacy.

Hybrid SPECT-CT: Integration of CT coronary artery calcium scoring and angiography with myocardial perfusion

A natural extension of current imaging paradigms for diagnosing coronary artery disease may well be the integration of CT with myocardial perfusion single-photon CT (SPECT). Although there is a wealth of clinical information regarding the utility of SPECT, the value of CT in the cardiology arena has only recently been explored. CT has the advantage of detecting coronary atherosclerosis at its earliest stages, allowing initiation of appropriate therapeutic measures well before development of obstructive coronary artery disease. However, SPECT can clarify the anatomic findings of CT based on a functional assessment of myocardial blood flow, thereby guiding management decisions. Hybrid imaging with SPECT and CT angiography may prove important from a diagnostic and therapeutic view point in several clinical scenarios, and it is likely that over the next decade fusion imaging may more precisely tailor therapy, reduce healthcare costs, and improve patient outcome.

Five-year follow-up in patients after therapy stratification based on intracoronary pressure measurement

BACKGROUND

Invasive coronary angiography (ICA) alone fails to accurately select patients with intermediate stenoses who should be treated by percutaneous coronary intervention (PCI). Previous studies have demonstrated the usefulness of fractional flow reserve (FFR) for identifying patients in whom deferring an intended PCI would be more beneficial than performing the planned procedure. The long-term safety of FFR-based therapy stratification, however, remains unknown. Therefore, the aim of this study was to retrospectively evaluate the long-term safety of an FFR-based therapy stratification in patients with intermediate coronary lesions detected by ICA.

METHODS

We included 56 patients presenting with a 50% to 75% angiographic stenosis by visual assessment on ICA, with negative, inconclusive, or no stress test, and in whom the intended PCI was deferred based on the result of the FFR measurement (ie, FFR > or = 0.75). The occurrence of major adverse cardiac events during a 5-year follow-up period was recorded.

RESULTS

A complete 5-year follow-up was available in all patients. Mean follow-up was 1868 +/- 380 days. During follow-up, 16 events (1 cardiac death, 4 noncardiac deaths, 11 revascularization procedures) occurred. The combined rate of cardiac death and nonfatal myocardial infarction was 1.8% over 5 years. Nine PCI procedures (5 target vessel, 4 nontarget vessel) were performed during follow-up based on objective signs of ischemia. The angina status was not different between inclusion and the 5-year follow-up.

CONCLUSION

Deferring PCI in patients without critical reduction in FFR may be a safe option during long-term follow-up.

An Initial Strategy of Intensive Medical Therapy Is Comparable to That of Coronary Revascularization for Suppression of Scintigraphic Ischemia in High-Risk But Stable Survivors of Acute Myocardial Infarction

OBJECTIVES

The purpose of this study was to determine the relative benefit of intensive medical therapy compared with coronary revascularization for suppressing scintigraphic ischemia.

BACKGROUND

Although medical therapies can reduce myocardial ischemia and improve patient survival after acute myocardial infarction, the relative benefit of medical therapy versus coronary revascularization for reducing ischemia is unknown.

METHODS

A prospective randomized trial in 205 stable survivors of acute myocardial infarction was made to define the relative efficacy of an intensive medical therapy strategy versus coronary revascularization for suppressing scintigraphic ischemia as assessed by serial gated adenosine Tc-99m sestamibi myocardial perfusion tomography. All patients at baseline had large total (> or =20%) and ischemic (> or =10%) adenosine-induced left ventricular perfusion defects and an ejection fraction > or =35%. Imaging was performed during 1 to 10 days of hospital admission and repeated in an identical fashion after optimization of therapy. Patients randomized to either strategy had similar baseline demographic and scintigraphic characteristics.

RESULTS

Both intensive medical therapy and coronary revascularization induced significant but comparable reductions in total (-16.2 +/- 10% vs. -17.8 +/- 12%; p = NS) and ischemic (-15 +/- 9% vs. -16.2 +/- 9%; p = NS) perfusion defect sizes. Likewise, a similar percentage of patients randomized to medical therapy versus coronary revascularization had suppression of adenosine-induced ischemia (80% vs. 81%; p = NS).

CONCLUSIONS

Sequential adenosine sestamibi myocardial perfusion tomography can effectively monitor changes in scintigraphic ischemia after anti-ischemic medical or coronary revascularization therapy. A strategy of intensive medical therapy is comparable to coronary revascularization for suppressing ischemia in stable patients after acute infarction who have preserved LV function.

To what degree is amelioration of angina following coronary revascularization associated with improvement in myocardial perfusion?

OBJECTIVE

To examine the association between changes in chest pain and changes in perfusion following revascularization as assessed by clinical evaluation and myocardial perfusion imaging (MPI) in patients with stable angina.

DESIGN

In a prospective series of 380 patients (58.8 +/- 8.8 years) referred to angiography because of known or suspected stable angina, changes in chest discomfort and changes in perfusion after 2 years were assessed in 144 patients, who underwent revascularization, and 236, who did not. The decision to treat invasively was made without knowledge of the result of MPI.

RESULTS

In revascularized patients, the presence of typical/atypical angina was reduced from 93% to 36% and the improvement was associated with improvement in perfusion. A small improvement in perfusion induced a high frequency of change from angina to no pain, whereas a further reduction caused little extra change. In non-revascularized patients the change in chest discomfort was not related to changes in perfusion, which were rarely present.

CONCLUSION

Alleviation of chest discomfort 2 years after revascularization is associated with improvements in perfusion. This association appeared to be an all-or-nothing phenomenon. Non-revascularized patients also exhibited improvements in chest discomfort despite insignificant changes in perfusion.

Cardiovascular imaging to quantify the evolution of cardiac diseases in clinical development

Cardiovascular diseases are the leading causes of mortality in western countries, leading to the development of a large set of preventive and curative treatments. Medical imaging is the gold standard to evaluate both cardiac perfusion and cardiac function and can be used even before the advent of hard events to accurately assess treatment effects. This study reviews the different image modalities that can be used to evaluate the evolution of cardiac diseases, especially coronary artery diseases. It also reviews different techniques heavily relying upon image co-registration techniques and population model designs that enable accurate quantitative evaluation of cardiac perfusion and cardiac function through time. It will draw the pros and cons of the different imaging modalities in actual clinical trials: Gated or tagged MRI, MRI for perfusion, PET, SPECT, Gated SPECT, MUGA, Ultrasound. This study also details the latest advances in quantification of cardiac SPECT, which has wide use in clinical trials today.

Effect of aggressive risk factor modification on cardiac events and myocardial ischaemia in patients with chronic kidney disease

OBJECTIVE

To examine whether aggressive risk factor modification in chronic kidney disease (CKD) can limit the development of new ischaemia or reduce cardiac events.

METHODS

Patients with CKD were randomly assigned to either an aggressive risk factor modification strategy (targeted treatment of hypertension, dyslipidaemia, homocysteine, haemoglobin and phosphate) or standard care. An intention to treat analysis was performed on 152 patients who had baseline dobutamine stress echocardiography (DSE), including 107 who had follow-up DSE. Biochemical parameters, cardiac risk factors and investigations (ECG, two-dimensional echocardiography) were recorded at baseline. New ischaemia was classed as new or worsening stress wall motion abnormality between follow-up and baseline DSE. Patients were followed up for the development of new ischaemia or cardiac death, acute coronary syndrome and non-fatal myocardial infarction over 1.8 years.

RESULTS

The development of new ischaemia was common but not different between the standard and aggressively treated groups (15 (21%) v 18 (23%), p = 0.8). Independent predictors of new ischaemia were older age, abnormal ECG, higher systolic blood pressure and lower serum high density lipoprotein cholesterol, but not treatment arm. The standard and aggressively treated groups did not differ in cardiac event rate (10% v 13%, p = 0.6) or all-cause mortality (10% v 19%, p = 0.2). In patients with an abnormal baseline DSE (non-diagnostic, scar or ischaemia), the event rate was similar (22% v 20%, p = 0.9).

CONCLUSION

Aggressive risk factor modification in CKD does not limit the development of new ischaemia or reduce cardiac events in patients with an abnormal DSE.

Noninvasive monitoring of medical therapy

An extensive literature base documents the substantial incremental prognostic value of nuclear cardiology compared with information provided by risk factors, clinical history, electrocardiographic stress testing results, and coronary arteriography. A smaller, well-established and growing literature addresses the unique potential of nuclear cardiology to assess therapeutic response of ischemic heart disease to lifestyle and medical therapies in individual patients. General guidelines focus on management of individual risk factors based on large studies, but may not reflect the optimum treatment strategy for an individual patient. The central rationale for noninvasive serial monitoring is to optimize the effectiveness and timing of lifestyle, medical, and revascularization therapies to minimize coronary event risk. Ideally, this monitoring of therapy should be early in the management of coronary artery disease (CAD) and guide the need for more intensive therapeutics. The application of technical advances in serial monitoring has the potential to revolutionize the way we diagnose and prevent CAD, even in asymptomatic patients. The potential long-term cost effectiveness of positron emission tomography and single-photon emission CT myocardial perfusion scintigraphy in detecting and monitoring treatment of CAD offers great promise for reducing coronary events in known or suspected ischemic heart disease.

Functional capacity and cardiovascular assessment: submaximal exercise testing and hidden candidates for pharmacologic stress

Submaximal exercise testing is often used to estimate functional capacity in non-athletes, to assess cardiovascular disease in elderly or frail patients, to demonstrate exercise equipment, or to risk-stratify patients after myocardial infarction. However, submaximal exercise testing is not sufficiently sensitive, specific, or predictive to have widespread clinical utility, except in post-myocardial infarction protocols. Many patients for whom submaximal exercise testing is not useful are unable to exercise sufficiently for maximal testing and are referred for imaging with pharmacologic stress. Although some patients who are unable to exercise adequately are easily recognized, many are not. The identification of such patients before they fail a maximal exercise test attempt is beneficial to both the patient and the imaging laboratory.

Sequential single-photon emission computed tomography myocardial perfusion imaging

The utility of stress myocardial perfusion imaging (MPI) for the diagnosis and prognosis of coronary artery disease (CAD) has been firmly established in numerous clinical studies and has become an essential component of clinical practice. Stress MPI is now used regularly to guide initial risk stratification and management of patients with CAD. Because stress MPI provides an assessment of the physiologic significance of CAD, it is a particularly attractive procedure for assessing follow-up risk. Today, sequential stress MPI is being used increasingly to track disease progression, assess follow-up risk, detect restenosis following revascularization, and evaluate the efficacy of aggressive medical therapy and risk-factor modification. By providing serial snapshots of the disease and its impact on perfusion, sequential stress MPI may alter treatment decisions and ultimately improve long-term patient management and outcomes. Use of sequential stress MPI to detect changes in perfusion following surgical or medical therapies is being tested currently in the Clinical Outcomes Using Revascularization and Aggressive Drug Evaluation (COURAGE) and Adenosine Sestamibi Single-Photon Emission Computed Tomography Postinfarction Evaluation (INSPIRE) trials.

Radionuclide-Based Insights into the Pathophysiology of Ischemic Heart Disease: Beyond Diagnosis

This review article discusses the historical origin of cardiac radionuclide-based methods, the physiologic background that justifies their existence, as well as the basic pathophysiologic concepts of coronary artery disease and their connection with the technologic design and application of these methods. Most importantly, this review discusses the important insights that these methods have provided to the understanding of the mechanisms of ischemia, risk stratification, and both treatment choice and treatment efficacy in ischemic heart disease. Nuclear cardiology originated as an attempt to provide complementary physiologic information to the anatomic information provided by coronary angiography. To comprehend the design and applications of nuclear cardiology methods, one must have a basic understanding of coronary artery disease as an inflammatory process that may manifest as acute or chronic states. Basic concepts on myocyte metabolic pathways, coronary blood flow, ischemic cascade, ventricular remodeling, and ejection fraction become critical for this purpose. Insights into risk stratification may permit patient-tailored therapy approaches. Insights into prognosis have made nuclear cardiology a robust tool for outcome predictions, with an exceptionally high negative predictive value. Evaluation of prognosis in special patient populations such as diabetics has originated important pathophysiologic concepts. Most insights into phenomena such as myocardial hibernation, myocardial stunning, and viability have been generated by nuclear cardiology techniques. Finally, new applications of radionuclide-based methods such as molecular identification of "vulnerable" atherosclerotic plaques, "ischemic memory" using fatty acid imaging, and myocardial innervation imaging provide new avenues for insightful research.

Prognostic value of adenosine Tl-201 myocardial perfusion imaging after acute myocardial infarction: results of a prospective clinical trial

BACKGROUND

We have previously shown in retrospective studies that adenosine myocardial perfusion imaging (MPI) done after acute myocardial infarction (AMI) can effectively predict the risk of future cardiac events in these patients. The objective of this study was to validate these observations in a prospective clinical trial.

METHODS AND RESULTS

One hundred twenty-six stable patients underwent quantitative adenosine MPI at a mean of 4.5 +/- 2.9 days after AMI. On the basis of the MPI results, they were divided into 3 risk groups: low risk (< 20% perfusion defect), intermediate risk (> or = 20% perfusion defect with < 10% ischemia), and high risk (> or = 20% perfusion defect with > 10% ischemia). The patients were followed up for 11 +/- 5 months for the occurrence of cardiac events: death, myocardial infarction, unstable angina, or congestive heart failure. The actual event rates correlated very well with the prespecified risk groups (19% for the low-risk group, 28% for the intermediate-risk group, and 78% for the high-risk group; P < .001). The significant multivariate predictors for events were female gender (relative risk [RR], 2.90; P = .002), left ventricular ejection fraction (RR, 1.34; P = .04), and ischemic defect size (RR, 1.46; P = .001), with a global chi2 value of 26.7.

CONCLUSION

This study demonstrates, in a prospectively designed clinical trial, that quantitative adenosine MPI performed soon after AMI can effectively predict the risk of future cardiac events. These findings are currently being validated in an ongoing, large, multicenter, international clinical trial.

Detecting changes in serial myocardial perfusion SPECT: a simulation study

BACKGROUND

New algorithms were evaluated for their efficacy in detecting and quantifying serial changes in myocardial perfusion from single photon emission computed tomography (SPECT).

METHODS AND RESULTS

We generated 72 simulations with various left ventricular positions, sizes, count rates, and perfusion defect severities using the nonuniform rational B-splines (NURBs)-based CArdiac Torso (NCAT) phantom. Images were automatically aligned by use of both full linear and rigid transformations and quantified for perfusion by use of the CEqual program. Changes within a given perfusion defect were compared by use of a Student t test before and after registration. Registration approaches were compared by use of receiver operating characteristic analysis. Changes of 5% were not detected well in single patients with or without alignment. Changes of 10% and 15% could be detected with false-positive rates of 15% and 10%, respectively, in single studies if alignment was performed before perfusion analysis. Alignment also reduced the number of studies necessary to demonstrate a significant perfusion change (P < .05) in groups of patients by about half.

CONCLUSION

Comparison of mean uptake by t values in SPECT perfusion defects can be used to detect 10% and greater differences in serial perfusion studies of single patients. Image alignment is necessary to optimize automatic detection of perfusion changes in both single patients and groups of patients.