Lawrence M. Phillips

Comparative Definitions for Moderate-Severe Ischemia in Stress Nuclear, Echocardiography, and Magnetic Resonance Imaging

The lack of standardized reporting of the magnitude of ischemia on noninvasive imaging contributes to variability in translating the severity of ischemia across stress imaging modalities. We identified the risk of coronary artery disease (CAD) death or myocardial infarction (MI) associated with ≥10% ischemic myocardium on stress nuclear imaging as the risk threshold for stress echocardiography and cardiac magnetic resonance. A narrative review revealed that ≥10% ischemic myocardium on stress nuclear imaging was associated with a median rate of CAD death or MI of 4.9%/year (interquartile range: 3.75% to 5.3%). For stress echocardiography, ≥3 newly dysfunctional segments portend a median rate of CAD death or MI of 4.5%/year (interquartile range: 3.8% to 5.9%). Although imprecisely delineated, moderate-severe ischemia on cardiac magnetic resonance may be indicated by ≥4 of 32 stress perfusion defects or ≥3 dobutamine-induced dysfunctional segments. Risk-based thresholds can define equivalent amounts of ischemia across the stress imaging modalities, which will help to translate a common understanding of patient risk on which to guide subsequent management decisions.

Lessons learned from MPI and physiologic testing in randomized trials of stable ischemic heart disease: COURAGE, BARI 2D, FAME, and ISCHEMIA

There is a preponderance of evidence that, in the setting of an acute coronary syndrome, an invasive approach using coronary revascularization has a morbidity and mortality benefit. However, recent stable ischemic heart disease (SIHD) randomized clinical trials testing whether the addition of coronary revascularization to guideline-directed medical therapy (GDMT) reduces death or major cardiovascular events have been negative. Based on the evidence from these trials, the primary role of GDMT as a front line medical management approach has been clearly defined in the recent SIHD clinical practice guideline; the role of prompt revascularization is less precisely defined. Based on data from observational studies, it has been hypothesized that there is a level of ischemia above which a revascularization strategy might result in benefit regarding cardiovascular events. However, eligibility for recent negative trials in SIHD has mandated at most minimal standards for ischemia. An ongoing randomized trial evaluating the effectiveness of randomization of patients to coronary angiography and revascularization as compared to no coronary angiography and GDMT in patients with moderate-severe ischemia will formally test this hypothesis. The current review will highlight the available evidence including a review of the published and ongoing SIHD trials.

Clinical role of the Duke Activity Status Index in the selection of the optimal type of stress myocardial perfusion imaging study in patients with known or suspected ischemic heart disease

BackgroundExercise treadmill stress myocardial perfusion imaging (MPI) with single photon emission computed tomography is commonly used to evaluate the extent and severity of inducible ischemia as well as to risk stratify patients with suspected and known coronary artery disease (CAD). Failure to reach adequate stress, defined as not attaining age-appropriate metabolic equivalents (METs), can underestimate the extent and severity of ischemic heart disease, resulting in false negative results. This study evaluates the efficacy of the Duke Activity Status Index (DASI), a simple self-administered 12-item questionnaire, as a predictor of METs achieved by treadmill stress testing.MethodsThe DASI was prospectively administered to 200 randomly selected men and women referred to the nuclear cardiology laboratory at New York University Langone Medical Center for stress MPI. Each patient was asked to complete the 12-item DASI questionnaire independently. 136 patients underwent treadmill exercise with MPI and 64 had pharmacologic stress with MPI. The association between exercise capacity in METs as estimated by the DASI questionnaire and performance on the Bruce treadmill protocol in METS was compared using chi-square statistics.ResultsOver 70% of those patients whose DASI score predicted the ability to perform <10 METs were unable to exercise beyond stage 2 of the Bruce protocol (7 METs). For those whose DASI score predicted ability to perform >12.5 METs, over 80% of patients reached >stage 2 of the Bruce protocol with 40% reaching beyond stage 3 (10 METs). When patient age was incorporated into the calculation, a more linear relationship was observed between predicted and obtained METs.ConclusionThe DASI is a simple self-administered questionnaire which is a useful pretest tool to determine a patient’s ability to achieve appropriate METs. In the nuclear cardiology laboratory, the DASI has the potential to guide selection of exercise treadmill vs pharmacologic stress and ultimately improve laboratory efficiency.

Myocardial perfusion imaging in women for the evaluation of stable ischemic heart disease—state-of-the-evidence and clinical recommendations

This document from the American Society of Nuclear Cardiology represents an updated consensus statement on the evidence base of stress myocardial perfusion imaging (MPI), emphasizing new developments in single-photon emission tomography (SPECT) and positron emission tomography (PET) in the clinical evaluation of women presenting with symptoms of stable ischemic heart disease (SIHD). The clinical evaluation of symptomatic women is challenging due to their varying clinical presentation, clinical risk factor burden, high degree of comorbidity, and increased risk of major ischemic heart disease events. Evidence is substantial that both SPECT and PET MPI effectively risk stratify women with SIHD. The addition of coronary flow reserve (CFR) with PET improves risk detection, including for women with nonobstructive coronary artery disease and coronary microvascular dysfunction. With the advent of PET with computed tomography (CT), multiparametric imaging approaches may enable integration of MPI and CFR with CT visualization of anatomical atherosclerotic plaque to uniquely identify at-risk women. Radiation dose-reduction strategies, including the use of ultra-low-dose protocols involving stress-only imaging, solid-state detector SPECT, and PET, should be uniformly applied whenever possible to all women undergoing MPI. Appropriate candidate selection for stress MPI and for post-MPI indications for guideline-directed medical therapy and/or invasive coronary angiography are discussed in this statement. The critical need for randomized and comparative trial data in female patients is also emphasized.

Noninvasive Assessment of Coronary Artery Disease in Women: What's Next?

Significant progress in research has been made in the areas of sex-specific aspects of cardiovascular disease. Despite these advances, coronary artery disease (CAD) is the leading cause of death of women in the Western world. Over the past decade, the focused research on women at risk for ischemic heart disease has helped to clarify our understanding of some of the sex-specific factors, which are important in detecting CAD. In women, the detection and evaluation of physiologically significant CAD is challenging, especially given that traditional tests designed to detect focal areas of coronary artery stenosis are less sensitive and specific in female patients who have a lower prevalence of obstructive coronary disease, greater burden of symptoms, and a high atherosclerotic burden. In this article, we review the available evidence on the role of contemporary cardiovascular imaging techniques in evaluating ischemic heart disease in women.

Mandatory Diagnostic Angiography for Carotid Artery Stenosis Prior to Carotid Artery Intervention

INTRODUCTION Revascularization is an important strategy for reducing stroke risk in patients with severe carotid atherosclerosis. Magnetic resonance angiography (MRA) and/or carotid ultrasound have traditionally been used as the only diagnostic modalities prior to revascularization. Patients undergoing CEA frequently have no further assessments of carotid anatomy prior to surgery. Evaluation with carotid ultrasound and MRA can often overestimate the degree of stenosis. We sought to determine if noninvasive imaging was sufficient for determining whether a patient should be referred for carotid intervention. METHODS We performed an analysis of 101 patients referred for carotid artery stenting (CAS). All patients had previously been evaluated with carotid ultrasound and 94% had undergone MRA as well. We sought to determine if noninvasive diagnostic imaging for carotid stenosis was sufficient to determine the necessity for endovascular intervention. RESULTS Of the 101 patients referred for carotid intervention, 36 (36%) were shown to have <70% stenoses and did not require intervention. Of those who had significant disease, 49 (75%) underwent successful CAS, 15 (23%) underwent CEA, and 1 patient was treated medically for a total occlusion. Three of the 36 patients not requiring carotid intervention were found to have subclavian stenosis. Two (4%) of the patients undergoing CAS and 4 (27%) of the patients undergoing CEA had minor complications. No patients suffered a major stroke, MI, or death at follow-up. CONCLUSION This analysis demonstrates that 36% of patients referred for endovascular intervention based on noninvasive imaging did not meet criteria by angiography. This emphasizes the need for carotid angiography prior to carotid intervention.

Optimising diagnostic accuracy with the exercise ECG: opportunities for women and men with stable ischaemic heart disease

The exercise ECG is an integral part within the evaluation algorithm for diagnosis and risk stratification of patients with stable ischaemic heart disease (SIHD). There is evidence, both older and new, that the exercise ECG can be an effective and cost-efficient option for patients capable of performing at maximal levels of exercise with suitable resting ECG findings. In this review, we will highlight the major dilemmas in interpreting suspected coronary artery disease symptoms in women and identify optimal strategies for employing exercise ECG as a first-line diagnostic test in the SIHD evaluation algorithm. We will highlight current evidence as well as recent guideline statements on this subject. Trial registration number NCT01471522; Pre-results.

The elusive role of myocardial perfusion imaging in stable ischemic heart disease: Is ISCHEMIA the answer?

Abstract The assessment of ischemia through myocardial perfusion imaging (MPI) is widely accepted as an index step in the diagnostic evaluation of stable ischemic heart disease (SIHD). Numerous observational studies have characterized the prognostic significance of ischemia extent and severity. However, the role of ischemia in directing downstream SIHD care including coronary revascularization has remained elusive as reductions in ischemic burden have not translated to improved clinical outcomes in randomized trials. Importantly, selection bias leading to the inclusion of many low risk patients with minimal ischemia have narrowed the generalizability of prior studies along with other limitations. Accordingly, an ongoing randomized controlled trial entitled ISCHEMIA (International Study of Comparative Health Effectiveness with Medical and Invasive Approaches) will compare an invasive coronary revascularization strategy vs a conservative medical therapy approach among stable patients with moderate to severe ischemia. The results of ISCHEMIA may have a substantial impact on the management of SIHD and better define the role of MPI in current SIHD pathways of care.

Approaches to measuring ejection fraction: Many tools, but how to decide which one?

In today’s clinical practice, non-invasive cardiac imaging is commonplace and utilized for assessment of left ventricular ejection fraction (LVEF). Evaluation of LVEF is important for diagnosis of heart disease and guiding decisions for pharmacologic and device-based therapies. Currently, several modalities are used for sequential evaluation of LVEF as an analysis of serial changes based on intercurrent treatments both for supportive (e.g., ACE inhibitors, beta blockers) as well as potential worsening (certain chemotherapeutic agents) functions. In addition to serial assessment for significant improvements and detection of clinical worsening, there is an inverse relationship between LVEF and cardiac mortality which is well established. The literature is replete with evidence supporting an LVEF evaluation for assessment of functional recovery after revascularization in patients with chronic coronary artery disease (CAD). Additional appropriate indications include evaluation of LVEF for comprehensive cardiac structural/perfusion assessment for which the LVEF is only part of the information obtained and is usually not the reason the particular test is chosen. Current modalities used for this comprehensive evaluation include gated SPECT/ PET, MRI, and CT. As well, for LVEF assessment, radionuclide angiography (RNA) is also frequently employed with transthoracic echocardiography saddling both indications as a primary indication for testing. In this issue of the Journal of Nuclear Cardiology, Yang et al expands these conventional approaches for LVEF assessment through the evaluation of computed tomographic evaluation assessment for rest LVEF in isolation of angiographic evaluation of the extent and severity of CAD. In this series, a total of 77 patients who were already scheduled to undergo LVEF assessment with RNA were also evaluated with an innovative CT LVEF protocol. CT images were post-processed with the evaluation of a semi-automatic volumetric algorithm. The LVEF was calculated utilizing measurements of end-diastolic and end-systolic LV volumes. Importantly, the mean estimated effective radiation dose for the LVEF assessment was 4.7 mSv for CT vs 9.5 mSv for RNA. For CT, the assessment of LVEF required 4 minutes of testing time which was less than the 9 minutes needed for RNA image acquisition. This difference became even more striking when compared to the total time for an RNA study of 85 minutes. In this report, Yang et al revealed a very strong correlation (r = .86) between the mean LVEF measured by RNA and CT. The observed LVEF measurements were statistically similar between CT and RNA with average values of 41.9% for CT and 39.4% for RNA (P[ 0.15). Although the P value was close to the borderline threshold, the observed differences between CT and RNA were clinically minimal. Using a Bland–Altman analysis, the mean difference between techniques was only 2.4% and unlikely to result in marked differences in categorization of LVEF for CT when compared to RNA. With regards to specific categories of LVEF, the kappa statistics were also very high when comparing CT to RNA. For LVEF measurements of B30% and C50%, the kappa statistics were .69 and .75, respectively. These findings are clinically important for the focus of imaging to be patient-centered as it allows for improved efficiency in the diagnostic evaluation and is See related article, pp. 414–421

Ankle‐Brachial Index Testing at the Time of Stress Testing in Patients Without Known Atherosclerosis

Individuals referred for stress testing to identify coronary artery disease may have nonobstructive atherosclerosis, which is not detected by stress tests. Identification of increased risk despite a negative stress test could inform prevention efforts. Abnormal ankle‐brachial index (ABI) is associated with increased cardiovascular risk.