Diagnosis and Screening of Coronary Artery Disease

Lifestyle Medicine and the Management of Cardiovascular Disease

PURPOSE OF REVIEW

Evidence has clearly demonstrated the importance of lifestyle factors (e.g., diet, physical activity, smoking) in the development of cardiovascular disease (CVD). Interventions targeting these behaviors may improve outcomes for CVD patients. The aim of this review is to summarize the effects of lifestyle interventions in individuals with established CVD.

RECENT FINDINGS

Most recent trials focused on diet, physical activity, stress reduction, or a combination of these. Findings were mixed, but most interventions improved at least some markers of cardiovascular risk. Few studies measured long-term clinical outcomes, but some suggested a possible benefit of stress reduction and multifaceted interventions on cardiovascular events. The benefits of lifestyle change for CVD patients have been established by decades of evidence. However, further research is needed to determine the optimal intensity, duration, and mode of delivery for interventions. Additional studies with long-term follow-up and measurement of clinical outcomes are also needed.

Noninvasive Cardiac Quantum Spectrum Technology Effectively Detects Myocardial Ischemia

Background

A standard resting electrocardiogram (ECG) shows limited sensitivity and specificity for the detection of coronary artery disease (CAD). Several analytic methods exist to enhance the sensitivity and specificity of resting ECG for diagnosis of CAD. We compared a new computer-enhanced, resting ECG analysis device, the cardiac quantum spectrum (CQS) technique, with coronary angiography in the detection of CAD.

Material/Methods

A consecutive sample of 93 patients with a history of suspected CAD scheduled for coronary angiography was evaluated with CQS before coronary angiography. The sensitivity and specificity of CQS and standard 12-lead ECG for detecting hemodynamically relevant coronary stenosis were compared, using coronary angiography as the reference standard. Kappa analysis was performed to assess the agreement between CQS severity scores and the level of stenosis determined by coronary angiography.

Results

The CQS system identified 78 of 82 patients with hemodynamically relevant stenosis (sensitivity, 95.1%; specificity, 63.6%; accuracy, 91.4%; positive predictive value, 95.1%; negative predictive value, 63.6%). Sensitivity and accuracy were much higher for CQS analysis than for the standard ECG. The Kappa value, assessing the level of agreement between CQS and coronary angiography, was 0.376 (P<0.001).

Conclusions

CQS analysis of resting ECG data detects hemodynamically relevant CAD with high sensitivity and specificity.

Stress echocardiography vs nuclear stress imaging in clinical cardiology

Stress echocardiography and nuclear stress imaging are important non-invasive tools in clinical cardiology. This review discusses the uses, strengths and limitations of these imaging modalities and looks at whether stress echocardiography can actually replace nuclear stress imaging.

Comparison of a two-lead, computerized, resting ECG signal analysis device, the MultiFunction-CardioGram or MCG (a.k.a. 3DMP), to quantitative coronary angiography for the detection of relevant coronary artery stenosis (>70%) - a meta-analysis of all published trials performed and analyzed in the US

BACKGROUND

Accurate, non-invasive diagnosis of, and screening for, coronary artery disease (CAD) and restenosis after coronary revascularization has been a challenge due to either low sensitivity/specificity or relevant morbidity associated with current diagnostic modalities.

METHODS

To assess sensitivity and specificity of a new computerized, multiphase, resting electrocardiogram analysis device (MultiFunction-CardioGram(sm) or MCG a.k.a. 3DMP) for the detection of relevant coronary stenosis (>70%), a meta-analysis of three published prospective trials performed in the US on patient data collected using the US manufactured device and analyzed using the US-based software and New York data analysis center from patients in the US, Germany, and Asia was completed. A total of 1076 patients from the three trials (US - 136; Germany - 751; Asia - 189) (average age 62 +/- 11.5, 65 for women, 60 for men) scheduled for coronary angiography, were included in the analysis. Patients enrolled in the trials may or may not have had prior angiography and/or coronary intervention. Angiographic results in all studies were classified for hemodynamically relevant stenosis (> 70%) by two US based angiographers independently.

RESULTS

Hemodynamically relevant stenosis was diagnosed in 467 patients (43.4%). The device, after performing a frequency-domain, computational analysis of the resting ECG leads and computer-database comparison, calculated a coronary ischemia "severity" score from 0 to 20 for each patient. The severity score was significantly higher for patients with relevant coronary stenosis (5.4 +/- 1.8 vs. 1.7 +/- 2.1). The study device (using a cut-off score for relevant stenosis of 4.0) correctly classified 941 of the 1076 patients with or without relevant stenosis (sensitivity-91.2%; specificity-84.6%; NPV 0.942, PPV 0.777). Adjusted positive and negative predictive values (PPV and NPV) were 81.9% and 92.6%, respectively (ROC AUC = 0.881 [95% CI: 0.860-0.903]). Subgroup analysis showed no significant influence of sex, age, race/nationality, previous revascularization procedures, resting ECG morphology, or participating center on the device's diagnostic performance.

CONCLUSIONS

The new computerized, multiphase, resting ECG analysis device (MultiFunction-CardioGram(sm)) has been shown in this meta-analysis to safely and accurately identify patients with relevant coronary stenosis (>70%) with high sensitivity and specificity and high negative predictive value. Its potential use in the evaluation of symptomatic patients suspected to suffer from coronary disease/ischemia is discussed.

Detection of non-ST-elevation myocardial infarction using magnetocardiogram: new information from spatiotemporal electrical activation map

BACKGROUND AND AIM

Non-ST-segment elevation myocardial infarction (NSTEMI) cannot be easily detected in the emergency room. We evaluate a method to detect NSTEMI using 64-channel magnetocardiography (MCG).

METHODS

MCG recordings were made in 20 NSTEMI patients (aged 59.7+/-12.4 years), 15 young (aged 26.8+/-3.4 years), and 13 age-matched control subjects (aged 57.3+/-3.6). We evaluated three approaches to analysis, including 1) determination when individual subjects' MCG results fell outside normal ranges for ten MCG parameters, 2) the magnetic field map at the T-wave peak (T-MFM), and 3) a pair of spatiotemporal activation graphs (STAGs) showing two projections of electrical excitation during repolarization.

RESULTS

Significant differences were found between normal controls and patients for all MCG parameters. None of the healthy controls had more than four MCG abnormal parameters, whereas 19 NSTEMI patients (95%) were abnormal in more than four parameters. STAGs and T-MFM also showed clear differences between healthy controls and NSTEMI patients.

CONCLUSIONS

These results suggest that the MCG is sensitive to changes in the cardiac electrical pathway after myocardial infarction as described by these graphs and parameters, and therefore MCG may be a useful tool to detect severe ischemic patients.

Computerized 2-lead resting ECG analysis for the detection of relevant coronary artery stenosis in comparison with angiographic findings

To assess the sensitivity and specificity of a new computer-enhanced resting electrocardiographic analysis device for the detection of coronary stenosis, 189 patients (aged 61.3+/-12.9 years, 57 women) scheduled for coronary angiography from 4 Asian centers were included in an observational study. Angiographic results were independently classified for hemodynamically relevant stenosis by 2 angiographers. The device calculated a severity score from 0 to 20. The score was significantly higher for patients with coronary stenosis (5.4+/-1.8 vs 1.7+/-2.1). The study device (cutoff 4.0) identified 73 of 77 patients with stenosis (sensitivity 94.8%, specificity 86.6%). Adjusted positive and negative predictive values were 78.4% and 97.1%, respectively (receiver operating characteristic area under the curve, 0.914 [95% confidence interval, 0.868-0.961]). Subgroup analysis showed no significant influence of sex, age, previous revascularization procedures, or participating center. The new computer-enhanced, resting electrocardiographic analysis device appears to identify patients with relevant coronary stenosis with high sensitivity and specificity.

Computerized two-lead resting ECG analysis for the detection of coronary artery stenosis after coronary revascularization

BACKGROUND

Resting electrocardiogram (ECG) shows limited sensitivity and specificity for the detection of coronary artery disease (CAD), where patients with a history of coronary revascularization may pose special challenges. Several methods exist to enhance sensitivity and specificity of resting ECG for diagnosis of CAD, but such methods are not better than a specialist's judgement. We compared a new computer-enhanced, resting ECG analysis device, 3DMP, to coronary angiography to evaluate the device's accuracy in detecting hemodynamically relevant CAD.

METHODS

A convenience sample of 172 patients with a history of coronary revascularization scheduled for coronary angiography was evaluated with 3DMP before coronary angiography. 3DMP's sensitivity and specificity in detecting hemodynamically relevant coronary stenosis as diagnosed with coronary angiography were calculated as well as odds ratios for the 3DMP severity score and coronary artery disease risk factors.

RESULTS

The 3DMP system accurately identified 50 of 55 patients as having hemodynamically relevant stenosis (sensitivity 90.9%, specificity 88.0%). Positive and negative predictive values for the identification of coronary stenosis as diagnosed in coronary angiograms were 62.7% and 97.8% respectively. Risk and demographic factors in a logistic regression model had a markedly lower predictive power for the presence of coronary stenosis in these patients than did 3DMP severity score (odds ratio 2.04 [0.74-5.62] vs. 73.57 [25.10-215.68]). A logistic regression combining severity score with risk and demographic factors did not add significantly to the prediction quality (odds ratio 80.00 [27.03-236.79]).

CONCLUSIONS

3DMP's computer-based, mathematically derived analysis of resting two-lead ECG data provides detection of hemodynamically relevant CAD in patients with a history of coronary revascularization with high sensitivity and specificity that appears to be at least as good as those reported for other resting and/or stress ECG methods currently used in clinical practice.

Performing stable angina pectoris: an ethnographic study

Symptoms play a crucial part in the formulation of medical diagnoses, yet the construction and interpretation of symptom narratives is not well understood. The diagnosis of angina is largely based on symptoms, but a substantial minority of patients diagnosed with "non-cardiac" chest pain go on to have a heart attack. In this ethnographic study our aims were to understand: (1) how the patients' accounts are performed or enacted in consultations with doctors; (2) the ways in which ambiguity in the symptom narrative is managed by doctors; and (3) how doctors reach or do not reach a diagnostic decision. We observed 59 consultations of patients in a UK teaching hospital with new onset chest pain who had been referred for a specialist opinion in ambulatory care. We found that patients rarely gave a history that, without further interrogation, satisfied the doctors, who actively restructured the complex narrative until it fitted a diagnostic canon, detaching it from the patient's interpretation and explanation. A minority of doctors asked about chest pain symptoms outside the canon. Re-structuring into the canonical classification was sometimes resisted by patients who contested key concepts, like exertion. Symptom narratives were sometimes unstable, with central features changing on interrogation and re-telling. When translation was required for South Asian patients, doctors considered the history less relevant to the diagnosis. Diagnosis and effective treatment could be enhanced by research on the diagnostic and prognostic value of the terms patients use to describe their symptoms.

Computerized two-lead resting ECG analysis for the detection of coronary artery stenosis

BACKGROUND

Resting electrocardiogram (ECG) shows limited sensitivity and specificity for the detection of coronary artery disease (CAD). Several methods exist to enhance sensitivity and specificity of resting ECG for diagnosis of CAD, but such methods are not better than a specialist's judgement. We compared a new computer-enhanced, resting ECG analysis device, 3DMP, to coronary angiography to evaluate the device's accuracy in detecting hemodynamically relevant CAD.

METHODS

A convenience sample of 423 patients without prior coronary revascularization was evaluated with 3DMP before coronary angiography. 3DMP's sensitivity and specificity in detecting hemodynamically relevant coronary stenosis as diagnosed with coronary angiography were calculated as well as odds ratios for the 3DMP severity score and coronary artery disease risk factors.

RESULTS

3DMP identified 179 of 201 patients with hemodynamically relevant stenosis (sensitivity 89.1%, specificity 81.1%). The positive and negative predictive values for identification of coronary stenosis as diagnosed in coronary angiograms were 79% and 90% respectively. CAD risk factors in a logistic regression model had markedly lower predictive power for the presence of coronary stenosis in patients than did 3DMP severity score (odds ratio 3.35 [2.24-5.01] vs. 34.87 [20.00-60.79]). Logistic regression combining severity score with risk factors did not add significantly to the prediction quality (odds ratio 36.73 [20.92-64.51]).

CONCLUSIONS

3DMP's computer-based, mathematically derived analysis of resting two-lead ECG data provides detection of hemodynamically relevant CAD with high sensitivity and specificity that appears to be at least as good as those reported for other resting and/or stress ECG methods currently used in clinical practice.

Cardiovascular disease: strategies for risk assessment and modification

Cardiovascular disease is the leading cause of death among men and women in the United States. Silent myocardial ischemia, defined as documentation of ischemia in the absence of angina or anginal equivalents, affects up to 4 million Americans and carries a poor prognosis. The assessment of the presence of subclinical coronary atherosclerosis affords an opportunity to identify patients who may be at risk for coronary artery disease over the long term. In addition to traditional risk factors (such as lipid parameters, diabetes, hypertension, smoking, and age), a variety of novel factors (such as lipoprotein[a], homocysteine, and C-reactive protein) may enhance assessment of risk in specific populations. Risk modification should be aimed at achieving recommended levels of lipids and blood pressure, reducing obesity, facilitating optimal management of diabetes and the metabolic syndrome, and encouraging smoking cessation and physical activity. Clinicians should be knowledgeable regarding the application of national guidelines for the reduction of cardiovascular risk so as to maximize the prospects for both the primary and secondary prevention of coronary artery disease and associated adverse outcomes.

Can magnetocardiography detect patients with non-ST-segment elevation myocardial infarction?

BACKGROUND AND AIM

Magnetocardiography (MCG) has been proposed as a noninvasive diagnostic tool to risk-stratify patients with myocardial infarction (MI) and ischemia. The purpose of this study is to find the MCG parameters that are sensitive enough to detect the non-ST-segment elevation myocardial infarction (NSTEMI) patients.

METHODS

MCG data were recorded and analyzed from 165 young controls (mean age = 27.2 +/- 9.0 years), 57 age-matched controls (mean age = 55.9 +/- 10.5 years) and 83 NSTEMI patients (mean age = 59.7 +/- 11.1 years). The MCG recordings were obtained using a 64-channel MCG system in a magnetically shielded room. Statistical analyses were performed for 24 parameters derived from QRS-, R-, T-wave, and ST-T period. Binary boundaries to detect NSTEMI patients out of control subjects were found using the receiver operating characteristic (ROC) curve for each parameter.

RESULTS

Fifteen parameters showed a significant difference (P < 0.05 and P < 0.01) between NSTEMI and both of the control groups. For detection of NSTEMI, the angle of the maximum current and the filed map angle on T-wave peak showed the highest diagnostic performance from 75% to 92% including accuracy, sensitivity, specificity, positive predictive value, and negative predictive value (area under ROC curve = 0.87 approximately 0.93).

CONCLUSIONS

Our study showed that MCG has potential clinical application for detection of NSTEMI and should be further investigated.

The future may be closer than you think: a response from the Personalized Medicine Coalition to the Royal Society's report on personalized medicine

A recent report from the British Royal Society on the prospects for personalized medicine provides a sobering assessment of the field and its prospects. The report contends that pharmacogenetics has little clinical relevance at the moment and will only progress with the completion of large, cumbersome clinical trials. The report goes on to note that the regulatory infrastructure, medical education initiatives and public deliberation necessary to make personalized medicine a reality are essentially nonexistent, at least so far. In our view, personalized medicine is much more than a hypothetical protocol designed to correlate genotypes with prescriptions. We argue that the development of personalized medicine is a broader phenomenon that is already being practiced in one form or another in many contexts. Both academic medicine and the pharmaceutical industry have a huge stake in bringing pharmacogenetic-based personalized medicine to fruition; we expect both entities to act as drivers of what will be a long-term, iterative process.

Ultrasonic Doppler vibrometry: measurement of left ventricular wall vibrations associated with coronary artery disease

We have developed a new method of detecting coronary artery stenoses that uses Doppler ultrasound to measure minute local vibrations in the cardiac wall associated with post-stenotic flow turbulence. In this paper, we present the results of a preliminary clinical study to evaluate the efficacy of this method for detecting coronary artery disease (CAD) using coronary angiography as the gold standard. The study population consisted of 34 patients clinically-indicated for coronary angiography. Based on the catheterization reports, the patients were divided into three categories: severe (obstructive CAD, typically with >70% diameter reduction), moderate (non-obstructive CAD, typically with <50% diameter reduction or diffuse atherosclerosis), and normal (no angiographic evidence of CAD). A diastolic myocardial vibration index (DMVI) was calculated as the ratio of the normalized periodogram spectral energy in the 100~800-Hz frequency band of the instantaneous wall velocity in early diastole to a baseline value during diastasis. The DMVI was significantly higher in severe CAD patients (21.2 +/- 3.2 dB) compared to moderate CAD (17.5 +/- 3.5 dB) and normal (11.2 +/- 4.8 dB). The differences between each of the categories were statistically significant (p<0.05). Severe CAD patients could be distinguished from normal with a sensitivity of 91.7% and specificity of 83.3%. We believe that this method could potentially be developed into a low-cost and accurate test for diagnosis and screening for coronary artery stenosis.