Angiographic definition of critical coronary artery stenosis

In summary, it is hazardous to rely solely on coronary angiography to define critical coronary stenosis. Clinically, the physiologic significance of a narrowing observed at coronary angiography can best be evaluated by obtaining additional evidence of myocardial ischemia, i.e. stress testing with ECG monitoring, resting and exercise isotope perfusion studies or ventriculographic studies. However, when evaluating coronary angiograms for critical coronary stenosis, several points are worth considering. First, a long narrowing will decrease coronary blood flow more than a short narrowing of the same severity. Second, sequential narrowings will decrease coronary blood flow more than a single narrowing of the same total length. Third, a long narrowing can be estimated more accurately than a short narrowing. Fourth, caliper measurements of coronary artery narrowings are more accurate than subjective estimation, and fifth, coronary artery dilators may increase the percentage narrowing in some cases. The complex effects of percent stenosis and length of stenosis on the physiology of coronary blood flow must always be considered when evaluating angiograms. In addition, the angiographic or photographic artifacts produced by short narrowings tend to overestimate the percent stenosis and, thus, calipers should be used to measure percent stenosis, especially in the short narrowings.

Detection and management of the asymptomatic patient with coronary artery disease

A clinician is faced with several dilemmas when evaluating the asymptomatic individual. The first dilemma relates to 'who should be evaluated'. Generally the first step in evaluation is the exercise stress test (fig. 2). The following are guidelines that can be used to systematically evaluate the individual asymptomatic patient who presents with a 'positive exercise stress test' (fig. 3). An ambulatory ECG can be performed to evaluate the occurrence and frequency of asymptomatic ST segment depression and the response to nitrates. Isotope angiography and exercise 201Tl perfusion studies may provide additional information relating to the physiologic significance of asymptomatic ST segment depression. If these studies are negative and the patients' 'positive stress test' was obtained at a high cardiac workload coupled with rapid normalization of the ST segment after exercise, and there was no change in the ST segment depression after nitroglycerin, a reasonable case can be made to simply observe the patient. If the exercise test is 'positive' at a low cardiac workload, associated with prolonged ST segment depression and/or a 'positive' exercise thallium or positive exercise angiography, or there was change in the ST segment depression after nitroglycerin or a lifethreatening arrhythmia developed, coronary angiography seems warranted.

Use of vasodilators in congestive heart failure

In order to select the proper vasodilator agent for the treatment of congestive heart failure, the underlying etiology and pathophysiology of heart failure must be understood since they are important determinants of the response to the particular vasodilator being used. Short-term studies are impressive. Most patients respond dramatically to vasodilators. Long-term studies are not available at this time. When they become available, the clinical usefulness of this group of drugs will be put in proper perspective.

How will INVEST and other hypertension trials change clinical practice?

Three large, ongoing, international clinical trials will greatly improve our understanding of hypertension management. The trials, which include the INternational VErapamil SR/trandolapril STudy (INVEST), the Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial (ALLHAT), and the Controlled ONset Verapamil INvestigation of Cardiovascular Endpoints (CONVINCE) trial, enrolled a combined total of 81,649 patients over a 7-year period from 18 different countries in North America, South America, Europe, and Australia-Asia. The mean age of all subjects was 66 years, and the mean body mass index (BMI) was 29.5. In addition, 30% of all patients had diabetes and 43% had documented coronary artery disease (CAD). In INVEST, 100% of enrolled patients had documented CAD and 27% had diabetes. Of patients treated for 12 months in INVEST, a systolic blood pressure (SBP) <140 mmHg was achieved by 70% of nondiabetics, and 66% of patients with diabetes achieved that level. Of all the patients enrolled in the three trials, 38% were smokers, 25% had a history of myocardial infarction (MI) or stroke, and 52% had a history of dyslipidemia. Although these clinical trials are likely to influence treatment guidelines, they may not affect the way medicine is practiced. A survey of primary care physicians found that 41% had not heard of or were not familiar with the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure (JNC VI) guidelines. The JNC VI and European guidelines provide management strategies based on severity of coronary risk factors, target organ damage, and blood pressure levels. Primary care physicians have a responsibility to be educated about risk stratification, goals of treatment based on risk, and management strategies for hypertension from available treatment guidelines.

Re-thinking angina

William Heberden in 1772 published "some account of the disorder of the breast" which contains the essential elements of angina pectoris as we understand it today. The number of existing cases in the U.S. population today is 6.4 million. Myocardial ischemia manifested by angina pectoris can be either acute or chronic. Patients with chronic stable angina will be the focus of this supplement. The majority of patients are symptomatic but approximately 25% can be asymptomatic. The clinical manifestations of myocardial ischemia generally are chest discomfort, arrhythmias, and LV dysfunction. Myocardial ischemia is a result of imbalance between myocardial oxygen supply and myocardial oxygen demand. High grade coronary stenosis are the usual cause of decreased oxygen supply. The classic hemodynamic factors increasing myocardial oxygen demand include hypertension and increased heart rate due to tachyarrhythmias of any etiology. Exertion is the usual precipitating cause of chronic myocardial ischemia. New information has come forward indicating that myocardial ischemia is associated with disruption of cellular sodium and calcium homeostasis. Ischemia results in a rise of intracellular sodium concentration and thus sodium overload which then activates the sodium calcium exchanger and leads to increased intracellular calcium. When this occurs there is electrical instability and mechanical dysfunction which increases oxygen demand and decreases oxygen supply. The compound Ranolazine is thought to selectively inhibit the late sodium current and attenuates the abnormalities of ventricular repolarization and contractility associated with myocardial ischemia. This compound is the first new class of anti-anginal medication approved in 25 years which may provide physicians with additional therapy for chronic stable angina along with the other anti-angina agents, beta blockers, calcium antagonists and nitrates.

Clinical and detailed angiographic findings in patients with ambulatory electrocardiographic ischemia without critical coronary narrowing: results from the Asymptomatic Cardiac Ischemia Pilot (ACIP) Study

BACKGROUND

Patients with ambulatory electrocardiographic (AECG) ST-segment depression and critical coronary narrowing are known to be at increased risk for adverse outcome, but little is known about patients with AECG ST-segment depression without critical coronary narrowing.

HYPOTHESIS

The objectives of this study were to characterize the coronary angiographic pathology in patients with AECG ST-segment depression but without critical (< 50% diameter stenosis) coronary narrowing and to compare demographic and clinical findings in these patients with those enrolled in the Asymptomatic Cardiac Ischemia Pilot Study with AECG ST-segment depression and critical (> or = 50% diameter stenosis) coronary narrowing.

METHODS

Coronary angiograms from patients with AECG ST-segment depression were reviewed in a central laboratory and quantitative measurement of percent stenosis was performed. Clinical and angiographic comparisons were made between patients with and without critical coronary narrowing.

RESULTS

Patients without critical coronary narrowing (n = 64) were younger (p = 0.02), less likely to be male (p < 0.001) or to have risk factors for coronary atherosclerosis or a history of myocardial infarction (p < 0.001), and had fewer ischemic episodes per 24 h on the screening AECG (p = 0.02) than patients with critical coronary narrowing (n = 441). Of patients without critical narrowing, one half had angiographic evidence for coronary artery disease (> or = 20% stenosis) and 60% had an ejection fraction > 70%.

CONCLUSIONS

Patients with AECG ST-segment depression without critical coronary narrowing are heterogeneous, with half having measurable coronary artery disease. Demographically and clinically, they appear to be different than patients with AECG ST-segment depression with critical coronary narrowing.

Continuing medical education and industry support

1. Industry and faculty of continuing medical education programs must agree that any supported program is for scientific and educational purposes only and not to promote a company's products directly or indirectly. 2. The control of content and selection of presenters and moderators must be independent of the company and determined by the program director. 3. Faculty of continuing medical education programs must disclose any financial relationship they have with the sponsoring company. 4. Program content cannot be scripted or influenced in any way by industry. 5. Objectivity and balance must be perceived by the audience. This includes the presentation of favorable and unfavorable information and alternative treatments. 6. Incomplete data must be identified by the faculty. Oftentimes, much of what is presented at continuing medical education programs has not yet been published in peer-reviewed journals. This must be so indicated by the presenter, and it should be specified whether incomplete data is on-going research, analysis, preliminary data, or unsupported opinion. 7. Support from industry must be in the form of an educational grant with no strings attached.

Intracardiac masses detected by echocardiography: case presentations and review of the literature

Intracardiac masses are often diagnosed by transthoracic echocardiography (TTE). Transesophageal echocardiography (TEE) improves overall visualization of masses, especially those located in the posterior cardiac structures. Masses in the heart are most commonly due to thrombi or valvular vegetations; however, a variety of tumors may also present as cardiac masses on echocardiography. Tumors of the heart most commonly occur in the setting of metastatic disease, usually from malignancies of the breast, lung, or from malignant melanoma. Primary cardiac tumors occur much less frequently and are usually benign. Atrial myxomas constitute nearly one-half of reported primary cardiac tumors. The following discussion details the findings of five cases that illustrate the spectrum of intracardiac tumors detected by echocardiography and reviews the relevant literature.

Low molecular weight heparin for acute ischemic heart disease

LMWH seems to me to be an attractive antithrombotic therapy that can be used in combination with antiplatelet treatment in patients with acute coronary syndromes. One of the advantages of LMWH is that home treatment becomes a possibility since the agent can be administered as subcutaneous injection without monitoring coagulation times. Therefore, in some patients, once they are stabilized and past the acute event, outpatient subcutaneous treatment with LMWH could be an attractive alternative to impatient treatment with intravenous heparin.