Incidence of immunoglobulin G antibodies to Chlamydia pneumoniae in acute myocardial infarction patients.

BACKGROUND: Recent studies have suggested a possible association between Chlamydia pneumoniae infection and coronary heart disease. OBJECTIVES: To determine titers of antibodies to C. pneumoniae in patients with acute myocardial infarction compared with titers in several control groups. METHODS: This prospective case-control study investigated 209 individuals. We assessed the serum IgG antibody titers to C. pneumoniae in 57 consecutive patients admitted with AMI to our intensive coronary care unit during a 4 month period. A serum sample was drawn upon admission and after 6 weeks. Results were compared with those of four control groups: a) patients admitted with community-acquired pneumonia (n = 18), b) patients with community-acquired urinary tract infection (n = 42), c) patients with angiographically normal coronary artery disease (n = 44), and d) patients with stable coronary artery disease (n = 48). Serum immunoglobulin G antibody titers to C. pneumoniae were determined using standard micro-immunofluorescence technology. RESULTS: Of 57 patients with AMI, 32 (56%) had a high IgG titer to C. pneumoniae (> or = 1:256) on the initial test, which remained unchanged (62%) after 6 weeks. The percentage of patients with high titers was significantly lower in the control groups: 5 of 18 patients (28%) in the pneumonia group (P < 0.01), 11 of 42 (26%) in the urinary tract infection group (P < 0.01), 11 of 44 (25%) with normal coronary arteries (P < 0.01), and 17 of 48 (35%) with stable chronic ischemic heart disease (P < 0.05). CONCLUSION: The detection of high titers of IgG antibodies to C. pneumonia in many patients with AMI, compared to control groups, suggests that chronic Chlamydia pneumoniae infection plays a role in the pathogenesis of atherosclerosis and acute ischemic events.

Cardioversion-induced fulminant ischaemic hepatitis.

Ischaemic hepatitis, although infrequent, should be considered as a cause of fulminant hepatitis in patients with congestive heart failure. Ischaemic hepatitis is characterized by a marked rise in transaminases occurring within 24-48 h of circulatory failure. Cardioversion of atrial fibrillation to sinus rhythm is associated with an increase in cardiac output in most patients; however, a transient reduction in cardiac output may occur in more than one-third of patients, and may therefore induce ischaemic hepatitis. This is the first report of fulminant ischaemic hepatitis as a complication of cardioversion of atrial fibrillation.

Value and limitations of ambulatory ECG monitoring for assessment of myocardial ischemia.

Ambulatory ECG monitoring (AEM) is the only available method to assess the presence and severity of myocardial ischemia during daily life. Several investigators have shown that the recording systems currently used can detect ischemic changes with similar accuracy as treadmill exercise testing. Ischemic changes on AEM are, however, present in only 40%-60% of patients with coronary artery disease (CAD) and positive exercise tests. For this reason, and because of the high day-to-day variability in daily ischemic changes, AEM cannot be used as a screening tool for detecting CAD or for evaluating severity of ischemia in individual patients. In patients with proven CAD, ischemic changes on AEM are associated with an adverse outcome in patients with stable and unstable ischemic syndromes, and in postmyocardial infarction patients. Suppression of daily ischemia seems to be associated with improved outcome. The mechanism of daily ischemia is not identical to exercise-induced ischemia. In addition to increased demand, which is a major contributor to AEM detected-ischemia, increased coronary tone also seems to play a major role. AEM has been shown to be a useful and reliable tool to assess the efficacy of various antiischemic drugs.

End organ protection by calcium-channel blockers.

In recent years, much attention has been given to end organ protection by antihypertensive, anti-heart failure, and anti-ischemic medications. This review describes the available information on end organ protection by calcium-channel blockers (CCBs). In normotensive patients and patients with hypertension treated with long-acting dihydropyridines, medial thickness was thinner than in patients treated with atenolol or in untreated hypertensive patients. Long-term treatment was associated with significant reduction in left ventricular mass. Calcium-channel blockers also improved endothelial-dependent relaxation and reversed the vasoconstrictive response to nitric oxide inhibitors. In diabetic patients, CCBs were effective in preserving kidney function and microalbuminurea. The combination of angiotensin-converting enzyme (ACE) inhibitors and CCBs was more effective than ACE inhibitors alone in preserving kidney function. In animal experiments, CCBs prevented development of coronary atheroschlerosis; however, in humans only limited data are available on their antiatherogenic effect. Some studies suggest that CCBs exert antiplatelets properties and may therefore be beneficial in patients with coronary artery disease.

The effect of mibefradil on ischemic episodes with and without increase in heart rate.

Myocardial ischemia during daily life can be induced by increased demand and by increased coronary tone. The purpose of this study was to assess the mechanism of action of mibefradil, a new T-channel calcium blocker that is a vasodilator with negative chronotropic properties. Included in this study were 114 patients with chronic stable angina pectoris and ischemic episodes during baseline 48-hour ambulatory ECG monitoring (AEM). After a placebo run-in period patients received 50 mg, 100 mg, or 150 mg of mibefradil per day and repeat 48 hours AEM was performed. Ischemic episodes were divided into 2 categories: Type I is those in which an increase in heart rate > 10% preceded the development of 1 mm ST depression; Type II is those with < or = 10% increase in heart rate. Of the 625 ischemic episodes recorded at baseline, 83% were Type I and 17% were Type II. At 50 mg mibefradil dose, there was a significant decrease in the number of Type I ischemic episodes but not of Type II. At doses of 100 mg and 150 mg/day, there was a significant decrease in frequency of both types of ischemic episodes. At a low dose of 50 mg/day, mibefradil reduces ischemia predominantly by preventing an increase in heart rate, while at higher doses of 100 mg and 150 mg/day, it also acted as a vasodilator suppressing episodes associated with increased coronary tone.

Effect of surgical repair of secundum-type atrial septal defect on right atrial, right ventricular, and left ventricular volumes in adults.

Surgical repair of atrial septal defect in adults reduces right ventricular and right atrial diameters and volumes, and improves left ventricular filling.

Myocardial preconditioning in humans.

The exact role of myocardial preconditioning in patients with coronary artery disease is not clear. Preconditioning rapidly develops during coronary angioplasty. Myocardial preconditioning probably plays a role in reducing the myocardial infarct size in patients with preceding angina by direct effect, rendering the myocytes more resistant to ischemic injury, by acceleration of thrombolysis, and probably by the increasing recruitment of collaterals. It is also possible that the higher mortality among diabetic patients on sulfonylureas, and their worse outcome during acute myocardial infarction, are related to blockade of preconditioning [39,40]. Myocardial preconditioning does exist during daily life, explaining the well-known phenomenon of "walk-though angina" and the more common "walk-through ischemia." It is hoped that drugs that mimic or enhance preconditioning will be developed, which will provide powerful myocardial protection.

Angina induced by excessive bradycardia.

Angina pectoris usually occurs in patients with significant coronary artery disease during periods of increased coronary demand such as increased heart rate. Bradycardia is a rare and unusal cause of angina pectoris that should be considered during the evaluation of patients with agnia. This paper reports three cases of bradycardia-induced angina.

Prevalence and significance of left ventricular outflow gradient during dobutamine echocardiography.

AIMS: This study investigated the clinical and physiological significance of the dynamic left ventricle outflow gradient observed in some patients during dobutamine stress echocardiography. METHODS: Three hundred and ninety-four consecutive patients completed dobutamine stress echocardiography using Doppler echocardiography to assess the presence of myocardial ischaemia and left ventricular outflow gradient. The prevalence of left ventricular outflow gradient was evaluated and correlated with echocardiographic and clinical findings. Fifteen patients with left ventricular outflow gradient during dobutamine infusion underwent exercise echocardiography for appearance of left ventricular outflow gradient. RESULTS: Sixty-nine of 394 (17.5%) patients developed a left ventricular outflow gradient of more than 36 mmHg. In nine of them (13%) the anterior mitral valve leaflet had a systolic anterior motion. In 60 of the 69 patients (87%) there was a dynamic obstruction at the level of the papillary muscles. The mean intracavitary gradient was 75.4 (range 36-175) mmHg. There was no correlation between the presence or absence of a dobutamine stress echocardiography-induced left ventricle outflow gradient and chest pain or shortness of breath. In patients who developed a left ventricular outflow gradient ischaemic wall motion abnormalities occurred at a significantly lower frequency during dobutamine stress echocardiography (2.9 vs 16.4% P<0.001). None of the 15 patients who underwent exercise echocardiography developed significant left ventricular outflow gradient. CONCLUSION: Left ventricular outflow gradient occurs occasionally during dobutamine stress echocardiography examination. Its presence is of no physiological or clinical significance.

Diagnostic value of 12-lead electrocardiogram during dobutamine echocardiographic studies.

BACKGROUND: The diagnostic value of 12-lead electrocardiography during dobutamine stress echocardiography (DSE) is not well documented. METHODS AND RESULTS: We reviewed the records of 116 patients referred for DSE and coronary angiography, 52 of whom were excluded because of abnormal ST segment or inadequate DSE. Of the analyzed 65 patients, 42 had angiographic evidence of significant coronary disease, 41 had evidence of ischemia according to the echocardiographic criteria, and 30 had ST changes during the study. DSE had sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 88%, 81%, 90%, and 78%, respectively. Twelve-lead electrocardiography had sensitivity, specificity, PPV, and NPV of 52%, 64%, 72%, and 41%, respectively. NPV increased to 92% in patients with negative DSE and negative ST changes. PPV increased to 95% if both DSE and 12-lead electrocardiographic ischemic changes were observed. CONCLUSIONS: Twelve-lead electrocardiography has an incremental diagnostic value when used during DSE.

Cardiovascular safety of transdermal nicotine patches in patients with coronary artery disease who try to quit smoking.

Nicotine patches are commonly used by people who try to quit smoking. Because high doses of nicotine may increase heart rate and potentiate cardiac arrhythmia or ischemia, its use in patients with coronary artery disease was investigated. The objective was to assess the cardiovascular safety of nicotine patches in patients with coronary artery disease (CAD) who try to quit smoking. The study was conducted in a double-blind, placebo-controlled, randomized fashion over a 2-week period. One hundred and six patients with CAD who wished to stop smoking and were taking part in a smoking cessation program were included. Fifty-two patients received nicotine patches (Nicotinell) and 54 received placebo patches. The cardiovascular effects of nicotine patches were assessed by repeated ambulatory ECG monitoring (AEM) and exercise testing. There were no changes in the resting heart rate and in the systolic or diastolic blood pressure between the screening and the two phases of the study in both the Nicotinell and placebo groups. Repeated 48-hour AEM revealed that there were no significant changes in the number and duration of ischemic episodes in both groups. There was no change in the frequency of atrial or ventricular arrhythmias. Exercise duration and time to 1-mm ST-segment depression increased in both groups during the double-blind treatment phase. More patients in the Nicotinell group claimed tobacco abstinence compared with the placebo group (27% vs. 13%). The use of nicotine patches did not cause aggravation of myocardial ischemia or arrhythmia in coronary patients and therefore can be used as a method to promote smoking cessation in this high-risk group.

Effect of lipid-lowering therapy on myocardial ischemia.

Myocardial blood flow in patients with coronary artery disease depends on the severity of the coronary narrowings and the functional status of the coronary vessels. Coronary atherosclerotic plaques, which contain high concentrations of lipids, are more sensitive to change in coronary tone. The increased tendency of these active plaques for vasoconstriction is caused by abnormal endothelial function. Because regression of significant coronary plaques is highly unlikely, effort is made to improve endothelial function, thereby improving myocardial blood flow. Reduction of the cholesterol level by lipid-lowering drugs is associated with restoration of the vasodilatory response of the coronary arteries, thereby reducing the likelihood of plaque rupture and its consequences: myocardial infarction and death. Myocardial ischemia during daily life is induced by increased demand and increased coronary tone; therefore, it was not surprising that recent studies have indicated that cholesterol lowering reduced the frequency of daily ischemic episodes. Because improvement in endothelial function is already observed within a few weeks/months of lipid lowering, it is hoped that this therapy will rapidly reduce the frequency and severity of myocardial ischemia and its clinical expression, angina pectoris. At a later phase (1-2 years), cholesterol lowering will also reduce major cardiac events.

Effect of metoprolol in reducing myocardial ischemic threshold during exercise and during daily activity.

In a study of 48 patients with coronary artery disease and evidence of ischemia during exercise and daily life, metoprolol reduced the threshold of myocardial ischemia in a dose-dependent manner. This effect of beta blockers is probably due to increased coronary tone.

Comparison of exercise hemodynamics among nonstented aortic bioprostheses, mechanical valves, and normal native aortic valves.

BACKGROUND: While aortic valve prostheses are known to perform well at rest, few studies have examined them under stress. We compared stress hemodynamics of mechanical valves and nonstented porcine valves in the aortic position to that of normal native aortic valves. METHODS: Dobutamine echocardiography was used to assess mean and peak gradients and effective orifice area index (EOAI) at rest and exercise in patients with the Toronto Stentless Porcine Valve (SPV) (n = 13, mean implant size 25.7 mm), Sorin Bicarbon mechanical valve (SOR) (n = 11, mean implant size 24.5 mm), and patients with normal native aortic valves (NOR) (n = 10). Dobutamine infusion was started at 5 micron/kg per minute, and increased by increments of 5 micron/kg per minute until the target heart rate was achieved or until a maximal dose of 40 micron/kg per minute. RESULTS: At rest and exercise, respectively, cardiac output (L/min) was 5.2 and 10.4 for Toronto SPV; 7.4 and 13.5 for SOR; and 4.6 and 11.2 for NOR. Measured EOAI (cm2) was 1.1+/-0.2 and 1.15+/-0.2 for TORONTO SPV; 1.60+/-0.3 and 1.58+/-0.3 for SOR; and 1.45+/-0.2 and 1.46+/-0.2 for NOR. Mean gradients (mmHg) were 5.48+/-1.1 and 5.83+/-0.9 for TORONTO SPV; 5.26+/-0.8 and 11.3+/-1.8 for SOR; and 1.54+/-0.4 and 2.18+/-0.7 for NOR. Peak gradients (mmHg) were 11.9+/-2.0 and 21.0+/-3.7 for TORONTO SPV; 10.79+/-1.7 and 25.9+/-3.4 for SOR; and 2.38+/-0.9 and 6.1+/-2.3 for NOR. CONCLUSIONS: Although the mechanical group (SOR) had larger measured EOAI, the greater increase in gradients with exercise in this group suggests that the TORONTO SPV is less obstructive to flow.