Coronary vasomotor effects of serotonin in patients with angina. Relation to coronary stenosis morphology

BACKGROUND

Previous experimental studies have shown that the effect of serotonin on a coronary stenosis depends on whether that stenosis is compliant or fixed. However, the relation between coronary stenosis morphology and the response to serotonin in patients with angina is not known.

METHODS AND RESULTS

Using computerized quantitative coronary angiography, we studied the effects of intracoronary infusion of serotonin on 38 coronary stenoses of different morphologies (concentric, eccentric, complicated) in 11 patients with stable angina and 4 with variant angina. In response to the maximum infused concentration of serotonin, 100% of complicated stenoses and 50% of concentric stenoses constricted by > or = 20% (P < .05). The magnitude of constriction was greater at eccentric stenoses (32.08 +/- 4.1%) than concentric stenoses (15.68 +/- 2.8%, P < .05) and greater in complicated stenoses (57.69 +/- 7.6%, P < .05) than eccentric stenoses. At complicated stenoses, the constriction was greater (0.85 +/- 0.16 mm, P < .05) than at the adjacent reference segments (0.42 +/- 0.12 mm). It was similar to the reference segment for both concentric and eccentric stenoses. The constriction at the stenosis was greater for irregular (complicated) lesions than for smooth (concentric and eccentric) lesions in both patients with stable (51.8 +/- 7.3% versus 22.5 +/- 4.1%, P < .001) and those with variant (77 +/- 17% versus 28.2 +/- 8.1%, P < .05) angina. There was a weak correlation (r = .39) of magnitude of constriction with stenosis length but not with baseline stenosis severity (minimum diameter).

CONCLUSIONS

In these patients, the magnitude of the vasoconstrictor response to serotonin at the site of an atheromatous coronary plaque depends on the morphological characteristics of the plaque and is more closely related to irregular contour than stenosis severity or length. This relation suggests that variations in receptor type or density or in the smooth muscle cell response to stimulation may determine the response to locally released serotonin in patients with coronary disease.

Comparison of regional myocardial blood flow in syndrome X and one-vessel coronary artery disease

Myocardial blood flow (MBF) was measured using continuous inhalation of oxygen-15-labeled carbon dioxide, and positron emission tomography before and after intravenous dipyridamole in 13 patients with syndrome X (angina pectoris, angiographically normal coronary arteries, positive exercise test and negative ergonovine test), 7 healthy subjects and 8 patients with 1-vessel coronary artery disease (CAD). In patients with syndrome X, baseline MBF was greater than in healthy subjects and patients with CAD (1.24 +/- 0.27 vs 0.87 +/- 0.07 and 1.03 +/- 0.23 ml/g/min, respectively; p < 0.05), and more heterogeneous (34 +/- 7 vs 26 +/- 5 and 25 +/- 6, respectively; p < 0.05) as assessed by the coefficient of variation among myocardial regions < or = 2.3 cm3. After dipyridamole, MBF in patients with syndrome X was similar to that in healthy subjects (2.95 +/- 0.75 vs 3.40 +/- 0.82 ml/g/min; p = NS) and greater than in patients with CAD (1.78 +/- 0.76 ml/g/min; p < 0.05). However in patients with both syndrome X and CAD, MBF was more heterogeneous than in healthy subjects (48 +/- 12 and 48 +/- 11, respectively, vs 30 +/- 7; p < 0.01). Thus, in patients with syndrome X, MBF is abnormally heterogeneous both at baseline and after dipyridamole. These findings are compatible with the presence of dynamic alterations of small coronary arteries. Because these alterations appear to be very sparse within the myocardium, they can be undetected when myocardial perfusion, function and metabolism are assessed using conventional methods that are unable to detect small myocardial regions.

Patterns of coronary artery stenosis vasomotion: observed versus "predicted" stenosis reactivity in patients with chronic stable angina

BACKGROUND

Patterns of constriction and dilatation of angiographically normal coronary artery segments and coronary stenoses, in response to vasoactive stimuli, remain speculative.

METHODS

We compared the vasomotor response of angiographically normal and stenotic coronary segments and assessed the effects of stenosis location and morphology on coronary stenosis vasomotion in 52 patients with chronic stable angina (40 men and 12 women) who underwent intracoronary ergonovine or isosorbide dinitrate administration or both. Changes in coronary diameter in response to nitrate and ergonovine were assessed by computed arteriography. The "predicted" change in stenosis diameter was calculated according to the "geometric theory" (based on the vasomotor response of angiographically normal segments adjacent to the lesion and on stenosis severity). Coronary diameter was assessed at baseline and after nitrate administration in 58 stenoses (34 concentric and 24 eccentric), of which 40 were located proximally and 18 distally, and also after ergonovine administration (23 stenoses: 14 proximal and 9 distal, 14 concentric and 9 eccentric).

RESULTS

Significant (> or = 10% lumen diameter change) vasoconstriction was observed after ergonovine administration in 14 of the 23 stenoses (61%), and significant vasodilation was noted after nitrate administration in 29 of 58 stenoses (50%). A larger proportion of distal (89%) and eccentric (89%) compared with proximal (43%) and concentric (43%) stenoses showed a greater than 10% vasoconstriction after ergonovine administration (P < 0.05). Vasodilatation after nitrate administration was also observed in a larger proportion of distal (78%) and eccentric (67%) than in proximal (38%) and concentric (38%) stenoses (P < 0.05). On average, the "observed" changes in coronary diameter in response to nitrate and ergonovine administration were of significantly less magnitude than those "predicted" by the geometric theory in both proximal and distal stenoses and in concentric and eccentric stenoses. In only 17% of stenoses were observed and predicted vasoconstriction similar.

CONCLUSIONS

Our results suggest that in patients with chronic stable angina, calculations based on the "geometric theory" cannot predict the actual vasomotor response of a stenosis. Factors other than severity, such as baseline coronary tone, stenosis location, and stenosis morphology, appear to modulate stenosis vasomotion in vivo.

Variability of coronary blood flow reserve assessed by Doppler catheter after successful thrombolysis in patients with acute myocardial infarction

To establish whether abnormal function of small coronary vessels might limit the advantages of thrombolytic treatment, coronary flow reserve in the infarct-related artery was measured in nine patients with acute myocardial infarction early after successful coronary thrombolysis by using a Doppler catheter and intracoronary adenosine infusion. In each patient coronary flow reserve was calculated as the ratio between coronary blood flow velocity during the highest tolerated intracoronary dose of adenosine (0.5 mg/min in five patients and 1 mg/min in four patients) and baseline velocity. Coronary flow reserve ranged from 1 to 3 (mean 2 +/- 0.7). No correlation (r = 0.20; p = 0.58) was found between coronary flow reserve and the severity of residual coronary stenosis, which ranged between 23% and 76% (mean 47% +/- 17%). No correlation (r = 0.33; p = 0.39) was found between either coronary flow reserve and the interval between pain onset and administration of the thrombolytic treatment, which ranged between 2.2 and 6 hours (mean 4.2 +/- 1.4 hours). Thus, in patients with acute myocardial infarction, coronary flow reserve early after successful thrombolysis is strikingly variable and may be extremely low despite widely patent epicardial coronary arteries. This restriction of coronary blood flow, probably caused by abnormal function of small coronary vessels, might limit the potential benefit from successful coronary thrombolysis.

Relation between stimulation site of cardiac afferent nerves by adenosine and distribution of cardiac pain: results of a study in patients with stable angina

OBJECTIVES

The purpose of this study was to establish whether stimulation of cardiac sensory receptors in different myocardial regions results in different distributions of cardiac pain.

BACKGROUND

Previous studies have shown that adenosine provokes cardiac pain through stimulation of sensory receptors in the absence of myocardial ischemia. In this study adenosine was used to obtain a regional stimulation of cardiac sensory receptors.

METHODS

Increasing doses of adenosine (0.25, 0.5 and 1 mg/min) were selectively infused into the right and then into the left coronary artery in 26 patients with stable angina.

RESULTS

No patient developed ischemic electrocardiographic changes during either adenosine infusion. Eighteen patients experienced cardiac pain during both infusions. Despite the stimulation of sensory receptors in different myocardial regions, 13 patients experienced cardiac pain in the same body area. Adenosine-induced pain was always similar to the anginal pain. By contrast, the remaining five patients experienced adenosine-induced cardiac pain in different body areas. In two of these patients, the distribution of anginal pain was similar to that experienced during one of the two adenosine infusions. In the remaining three patients, the distribution of anginal pain was similar to that experienced during adenosine infusion into the right coronary artery during some anginal episodes and to that experienced during adenosine infusion into the left coronary artery during other episodes.

CONCLUSIONS

During stimulation by adenosine of sensory receptors in different myocardial regions, the majority of patients experience cardiac pain in the same body area; only a few experience pain in different areas. These differences might be caused by different organizations of the ascending neural pathways to the cortex. Our results suggest that in the same patient different distributions of pain during anginal attacks are probably due to ischemia in different myocardial regions.

Variant angina pectoris. Role of coronary spasm in the development of fixed coronary obstructions

BACKGROUND

It has been suggested that recurring coronary artery spasm may lead to the development of fixed atherosclerotic coronary obstructions.

METHODS AND RESULTS

We studied 10 patients with typical Prinzmetal's variant angina in whom the disease remained active for years and in whom occlusive coronary spasm occurred reproducibly at the same arterial site during repeat coronary arteriography (25 +/- 12 months after initial angiography). At initial evaluation, four patients had significant (greater than or equal to 50% fixed coronary diameter reduction) one-vessel coronary artery disease, and six had nonsignificant disease. Spasm developed at stenotic sites (20-65% diameter reduction) in nine patients and at an angiographically normal site in one patient. Progression of coronary disease was assessed in 62 segments: 10 spastic (of which nine were stenotic) and 52 nonspastic (eight stenotic and 44 angiographically normal), using computerized arteriography. Mean diameters (millimeters) of spastic segments, nonspastic stenoses, and angiographically normal nonspastic segments were not significantly different at first and second arteriograms (1.52 +/- 0.14 versus 1.43 +/- 0.21, 1.32 +/- 0.17 versus 1.12 +/- 0.23, and 2.40 +/- 0.12 versus 2.42 +/- 0.12, respectively). Stenosis progression (from 65% diameter reduction to total occlusion) occurred in one patient at a spastic site and in two at nonspastic sites (from 34% to 65% and from 84% to 100%). Complicated stenoses suggestive of plaque fissuring were not observed during the study.

CONCLUSIONS

In patients with chronic Prinzmetal's variant angina without myocardial infarction, stenosis progression was not frequently observed at spastic sites despite the recurrence of focal coronary spasm over relatively long periods of time.

A combination of electrocardiographic methods represents a further step toward the noninvasive identification of patients with syndrome X

Identification of patients with angina but normal coronary arteriograms (syndrome X) using noninvasive means would be desirable. The ability of four established exercise electrocardiographic methods to identify angina patients with and without coronary artery disease was compared with that of a method based on a combination of the above (combined method). A treadmill score, a multivariate method, the ST segment recovery loop, the ST/heart rate adjustment, and the combined method were applied to 112 patients who had typical exertional angina and positive exercise tests (greater than 1 mm ST segment depression); 90 had documented coronary artery disease and 22 had syndrome X. The combined method and the treadmill score had a significantly higher diagnostic accuracy (both 81%, as 91 of the 112 patients were correctly identified by both methods) than the multivariate (66%) and ST segment recovery loop (64%) methods (p less than 0.05). The ST/heart rate adjustment had a lower sensitivity for syndrome X than any other method (1 of 22). Thus methods that involve the assessment of both ST and non ST segment variables have greater accuracy in separating syndrome X and coronary artery disease patients than methods relying more heavily on ST segment changes.

Preangioplasty complicated coronary stenosis morphology as a predictor of restenosis

To assess whether complicated preangioplasty coronary stenosis morphology is associated with restenosis, 41 patients (47 stenoses) who underwent repeat angiography 6 to 8 months after percutaneous transluminal coronary angioplasty (PTCA) were studied. Stenosis diameter and morphology were assessed by computerized quantitative coronary angiography before and immediately after PTCA and at follow-up angiography. Before PTCA 18 stenoses were concentric (symmetric narrowings with smooth borders), 12 were eccentric (asymmetric narrowings with smooth borders), and 17 were complicated (asymmetric with rough borders and overhanging edges). Restenosis occurred in 18 lesions: two (11%) concentric, four (33%) eccentric, and 12 (70%) complicated (p less than 0.05), whereas 29 lesions remained unchanged. Stenosis diameter before and immediately after PTCA was not significantly different in the 18 patients with and the 23 patients without restenosis. Follow-up angiograms showed that 11 (61%) stenoses in the group with restenosis and 18 (63%) in the group without restenosis had morphology similar to that before PTCA. Restenosis occurred in seven (30%) patients who initially had chronic stable angina and in 11 (61%) who were first seen with unstable angina (p less than 0.05). In patients with stable angina 1 of 13 concentric stenoses, two of eight eccentric stenoses, and four of five complicated lesions restenosed. In patients with unstable angina one of five concentric, two of four eccentric, and 8 of 12 complicated lesions had restenosis. Stenoses that were complicated before PTCA tended to adopt an irregular morphology if they recurred, whereas concentric stenoses rarely occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of oxyfedrine on regional myocardial blood flow in patients with coronary artery disease

Medical treatment of angina pectoris is largely based on the use of beta-blocking agents, calcium antagonists, and nitrates. Oxyfedrine, an amino ketone derivative and partial agonist at beta receptors, has been shown to have potent antianginal properties and to increase coronary blood flow in normal and ischemic myocardial regions in experimental studies. We assessed the effects of intravenous oxyfedrine on regional myocardial blood flow, using positron emission tomography (15-oxygen water), in six patients with chronic stable angina, positive exercise tests, and documented coronary artery disease. Myocardial blood flow was measured in all patients before (baseline) and 10 minutes after the intravenous administration of a single bolus (0.11-0.13 mg/kg) of oxyfedrine. Compared to baseline, heart rate and systolic blood pressure remained almost unchanged after the administration of oxyfedrine. Mean baseline myocardial blood flow was 0.90 +/- 0.15 ml/g/min in areas supplied by arteries with significant coronary stenosis and 1.08 +/- 0.19 ml/g/min in areas supplied by nonstenotic coronary vessels (p less than 0.05). After the administration of oxyfedrine, myocardial blood flow increased significantly in both the regions supplied by stenotic vessels (by 25%; from 0.90 +/- 0.15 to 1.20 +/- 0.31 ml/g/min; p = 0.002) and in areas supplied by angiographically normal coronary vessels (by 22%; from 1.08 +/- 0.19 to 1.38 +/- 0.49 ml/g/min; p less than 0.05). The results of this study indicate that in patients with coronary artery disease, intravenous oxyfedrine significantly increases regional myocardial blood flow, both in areas supplied by critically obstructed vessels and in areas supplied by normal or less severely narrowed coronary arteries.

Recovery-phase patterns of ST segment depression in the heart rate domain cannot distinguish between anginal patients with coronary artery disease and patients with syndrome X

Continuous plots of ST segment depression related to heart rate during exercise and recovery (heart rate recovery loops) can differentiate patients with coronary artery disease from clinically normal subjects. To assess whether this method can also distinguish patients with angina and coronary artery disease from those with syndrome X (angina, positive exercise tests, and normal coronary arteries), we studied 75 patients with coronary artery disease and 30 patients with syndrome X. The average heart rate recovery loops for coronary artery disease and syndrome X patients followed similar counterclockwise loop rotations. Individual data analysis, however, showed that in coronary artery disease patients the loop rotation was counterclockwise in 66 (88%) and intermediate in nine (12%), while none had a clockwise loop nine (30%), and intermediate in nine (30%). Thus heart rate recovery loops cannot distinguish patients with angina and coronary artery disease from those with syndrome X.

Absence of myocardial dysfunction during stress in patients with syndrome X

Stress two-dimensional echocardiographic studies were performed in 18 patients with angina, a positive exercise test and normal findings on coronary angiography (syndrome X). Rest and immediate posttreadmill exercise two-dimensional echocardiograms were performed with a digitized cine loop and side by side visual analysis in all patients. In 16 of these patients, right atrial pacing up to 160 beats/min was also performed and percent systolic wall thickening was calculated at five equally spaced segments around the left ventricle, each corresponding to an anterior, lateral and inferior wall and the posterior and the anterior ventricular septum. Measurements of percent systolic wall thickening were established in 10 age- and gender-matched normal persons for comparison. ST segment depression occurred in all patients during exercise and persisted for 42.1 s (range 18 to 75) into the recovery period. Immediate postexercise echocardiography was started within 20.1 +/- 5.4 s and completed in 54.1 +/- 11.3 s. No patient had regional wall motion abnormalities seen on two-dimensional imaging of any myocardial segment. Thirteen patients (72%) reported reproduction of their usual chest pain, which led to termination of the test. During rapid right atrial pacing, nine patients (56%) developed ST segment depression that was associated with angina in seven. In all 16 patients, percent systolic wall thickening increased over values at rest in each myocardial segment. Percent systolic wall thickening averaged 47.1 +/- 6.1% at rest and increased to 74 +/- 8% during right atrial pacing (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Heart rate response during exercise testing and ambulatory ECG monitoring in patients with syndrome X

The response of the heart rate during exercise testing and 24-hour ambulatory electrocardiographic (ECG) monitoring performed with patients not receiving antianginal treatment was assessed in 26 patients (9 men and 17 women; mean age 51 +/- 8 years) with syndrome X (angina pectoris with normal coronary arteries), in 27 patients with coronary artery disease (10 men and 17 women; mean age 55 +/- 9 years), and in 21 healthy subjects (8 men and 13 women; mean age 47 +/- 11 years). In patients with syndrome X the slope of the regression line of heart rate versus time (heart rate/time slope) during exercise testing was similar to that of patients with coronary artery disease (3.3 +/- 0.8 versus 3.1 +/- 1.2 beats/min), but significantly lower than that in healthy subjects (4.2 +/- 1.1 beats/min; p less than 0.003). In patients with syndrome X the intercept of the heart rate/time slope was significantly higher than that in coronary artery disease patients and healthy subjects (102 +/- 15, 86 +/- 18, and 90 +/- 16 beats/min, respectively; p less than 0.015). Resting preexercise heart rate was also significantly higher in syndrome X, compared with coronary artery disease patients and healthy subjects (91 +/- 16, 79 +/- 16, and 80 +/- 14 beats/min, respectively). During ambulatory ECG monitoring, mean diurnal heart rate (from 6 AM to 6 PM) was higher in patients with syndrome X (83 +/- 8 beats/min) than in patients with coronary artery disease (75 +/- 8 beats/min) and healthy subjects (74 +/- 11 beats/min) (p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Epicardial coronary artery tone and reactivity in patients with normal coronary arteriograms and reduced coronary flow reserve (syndrome X)

The vasomotor response of proximal and distal angiographically normal coronary artery segments was studied in 12 patients with syndrome X, 17 age- and gender-matched patients with chronic stable angina and 10 control subjects with atypical chest pain and a normal coronary arteriogram. Ergonovine (300 micrograms by intravenous injection) and isosorbide dinitrate (1 mg by intracoronary injection) were administered to all patients. Computerized coronary artery diameter measurement (angiographically normal segments only) was carried out before and after the administration of ergonovine and nitrate. Baseline intraluminal diameters (mean +/- SEM) of proximal and distal coronary segments were not significantly different in control subjects and patients with syndrome X or coronary artery disease (proximal 2.88 +/- 0.19, 3.01 +/- 0.13 and 2.86 +/- 0.13 mm; distal 1.57 +/- 0.09, 1.70 +/- 0.10 and 1.61 +/- 0.06 mm, respectively). With ergonovine, proximal segments constricted by 10 +/- 2%, 7 +/- 2% and 11 +/- 3% and distal segments by 12 +/- 3%, 14 +/- 3% and 14 +/- 2% in control subjects and patients with syndrome X or coronary artery disease, respectively (p = NS). With isosorbide dinitrate, proximal coronary segments dilated by 11 +/- 2%, 10 +/- 2% and 8 +/- 2% (p = NS) and distal segments by 15 +/- 2%, 11 +/- 3% and 13 +/- 2% (p = NS) in control subjects and patients with syndrome X or coronary artery disease, respectively. Within groups, constriction in response to ergonovine and dilation in response to nitrate were not significantly different in proximal and distal segments.(ABSTRACT TRUNCATED AT 250 WORDS)

Duration of ST segment depression after exercise-induced myocardial ischemia is influenced by body position during recovery but not by type of exercise

To assess whether the duration of ischemic ST segment depression after exercise can be modified by changes in body position during recovery or with different types of exercise, 18 patients with chronic stable angina, positive exercise test results, and documented coronary artery disease were prospectively studied. Every patient underwent testing with three different exercise protocols: (1) Bruce (Bruce-standing recovery), (2) abrupt onset of exercise (abrupt), and (3) modified Bruce protocol preceded by a 10-minute warm-up period (warm-up). After exercise test patients recovered in a sitting position. In addition, all patients performed a fourth exercise (Bruce protocol), but this time they recovered in the supine position (Bruce-supine recovery). Time and heart rate-blood pressure product at 1 mm ST segment depression were similar for Bruce-standing recovery, abrupt, and Bruce-supine recovery protocols (5.1 +/- 2, 4.4 +/- 2, and 5.2 +/- 2 minutes and 20.8 +/- 4, 21.3 +/- 4, and 20.4 +/- 4 beats/min x mm Hg x 10(-3), respectively. Heart rate and heart rate-blood pressure product at peak exercise did not differ in Bruce-standing recovery, abrupt, and Bruce-supine recovery. Maximal ST segment depression was -2.0, -1.9, and -2.0 mm with Bruce-standing recovery, abrupt, and Bruce-supine recovery exercise, respectively, and -1.5 mm with warm-up exercise (p less than 0.05). Duration of ST segment depression into recovery was significantly prolonged after Bruce-supine recovery exercise (9.4 + 5 minutes) compared with Bruce-standing recovery, abrupt, and warm-up protocols (6.8 + 3, 5.9 + 4, and 5.0 + 3 minutes, respectively; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Reactivity of proximal and distal angiographically normal and stenotic coronary segments in chronic stable angina pectoris

To assess whether vasoreactivity of significant coronary stenosis (greater than 50% intraluminal diameter reduction) and that of angiographically normal coronary segments differs in proximal and distal locations, 53 patients (40 men, 13 women, mean +/- standard deviation age 55 +/- 11 years) with chronic stable angina and angiographically documented coronary artery disease were studied. While abstaining from antianginal therapy, all 53 patients underwent coronary arteriography before and after 1 mg of intracoronary isosorbide dinitrate and 21 of the 53 also before and after 20 to 30 micrograms intracoronary ergonovine. Computerized quantitative angiography was used to assess changes in the intraluminal diameter of 126 normal coronary segments (63 proximal, 63 distal) and 43 significant coronary stenoses. Nitrates dilated proximal normal coronary segments by 7.4 +/- 1.2% and distal normal coronary segments by 15 +/- 1.7% (p less than 0.01). Significant proximal coronary stenoses dilated by 11 +/- 2.5% and distal stenoses by 23 +/- 2.8% (p less than 0.01) after nitrates. Ergonovine reduced the diameter of proximal normal coronary segments by 9.3 +/- 1.7% and that of normal distal segments by 15.5 +/- 1.4% (p less than 0.01). Proximal stenoses constricted by 11 +/- 2.2% and distal stenoses by 18.4 +/- 2.8% (p = 0.06). Analysis of segments showed that nitrates dilated 19 of 63 (30%) proximal normal segments by (greater than or equal to 10%), 31 of 63 (49%) distal (p less than 0.05) and 21 of 43 (49%) stenoses.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of epicardial coronary artery tone and reactivity in Prinzmetal's variant angina and chronic stable angina pectoris

It has been suggested that a generalized coronary vasomotion disorder is present in variant angina and that evaluation of baseline coronary artery tone may be useful for predicting the occurrence of coronary artery spasm. The vasomotor response of angiographically normal proximal and distal coronary artery segments was studied in 9 patients with atypical chest pain and normal coronary arteriograms (control group), 13 patients with active variant angina and 41 patients with chronic stable angina. Ergonovine (intravenous, 100 to 300 micrograms, or intracoronary, 8 to 20 micrograms, was administered to all 22 patients in the control and variant angina groups and to 11 of the 41 patients with chronic stable angina. All patients also received intracoronary isosorbide dinitrate (1 to 2 mg). Computerized coronary artery diameter measurement of angiographically normal segments was carried out before and after ergonovine and nitrate administration. Mean baseline intraluminal diameter of proximal and distal coronary segments was not significantly different in control patients and those with variant angina (nonspastic segments only) or coronary artery disease (proximal 2.89 +/- 0.15, 2.83 +/- 0.14 and 2.82 +/- 0.09 mm; distal 1.60 +/- 0.08, 1.63 +/- 0.07 and 1.62 +/- 0.06 mm, respectively). After ergonovine, proximal segments constricted by 10 +/- 2%, 15 +/- 3% and 11 +/- 4% and distal segments by 11 +/- 3%, 11 +/- 2% and 14 +/- 3% in control, variant angina and coronary artery disease groups, respectively (p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of intracoronary serotonin on coronary vessels in patients with stable angina and patients with variant angina

BACKGROUND

Serotonin, a major product of platelet activation, has potent vasoactive effects in animal models, but its role in human coronary artery disease remains largely speculative.

METHODS

Using quantitative coronary angiography, we compared the effects of the intracoronary infusion of graded concentrations of serotonin (10(-7) to 10(-4) mol per liter) on coronary vessels in two groups of patients with different clinical presentations of coronary disease (nine with stable angina and five with variant angina), with the effects in a control group of eight subjects with normal vessels on angiography.

RESULTS

Normal coronary vessels had a biphasic response to intracoronary serotonin: dilation at concentrations up to 10(-5) mol per liter, but constriction at 10(-4) mol per liter. Vessels in patients with stable angina constricted at all concentrations, with mean (+/- SEM) maximal decreases in diameter of 23.9 +/- 3.6, 33.1 +/- 3.9, and 41.7 +/- 3.1 percent from base line in proximal, middle, and distal segments at a serotonin concentration of 10(-4) mol per liter. Smooth segments constricted more than irregular segments (42.0 +/- 4.6 vs. 21.1 +/- 1.6 percent). Four patients with stable angina had a marked reduction in collateral filling. All the patients with stable angina had angina during the intracoronary infusion of serotonin, and electrocardiographic changes were noted in six. All the patients with variant angina had angina, electrocardiographic changes, and localized occlusive epicardial coronary-artery spasm at concentrations of 10(-6) (n = 2) or 10(-5) (n = 3) mol per liter.

CONCLUSIONS

Patients with stable coronary disease do not have the normal vasodilator response to intracoronary serotonin, but rather have progressive constriction, which is particularly intense in small distal and collateral vessels. Patients with variant angina have occlusive coronary-artery spasm at a dose that dilates normal vessels and causes only slight constriction in vessels from patients with stable angina. These findings suggest that serotonin, released after the intracoronary activation of platelets, may contribute to or cause myocardial ischemia in patients with coronary artery disease.

Reactivity of eccentric and concentric coronary stenoses in patients with chronic stable angina

Dynamic coronary stenoses may be the cause of a variable angina threshold and rest angina in patients with chronic stable angina. It has been suggested that eccentric but not concentric coronary artery stenoses have the potential for dynamic changes of caliber in response to vasoactive stimuli. The vasomotor response of eccentric (asymmetric narrowing) and concentric (symmetric narrowing) coronary stenoses to ergonovine (20 micrograms intracoronary or 300 micrograms intravenous) and isosorbide dinitrate (1 mg intracoronary) was studied in 51 patients with chronic stable angina. Diameter of reference segments (angiographically normal segments proximal to the stenoses) and that of eccentric (n = 30) and concentric (n = 35) coronary stenoses that ranged from 50% to 90% luminal diameter reduction were measured by computerized quantitative angiography before and after ergonovine and isosorbide dinitrate. Ergonovine reduced stenosis diameter (by greater than or equal to 10%) in 80% of eccentric stenoses and 42% of concentric stenoses (p less than 0.05). Mean (+/- SEM) diameter reduction with ergonovine was 19 +/- 3% and 9.5 +/- 2% for eccentric and concentric stenoses, respectively (p less than 0.05). Isosorbide dinitrate increased coronary diameter (by greater than or equal to 10%) in 70% of eccentric and 43% of concentric stenoses (p less than 0.05). Mean diameter of eccentric stenoses increased from 1.15 +/- 0.05 to 1.35 +/- 0.06 mm after nitrate (18.6 +/- 2.5%), whereas diameter of concentric stenoses increased from 1.05 +/- 0.05 to 1.14 +/- 0.05 mm (10 +/- 2.5%) (p less than 0.05). Average dilation of reference segments with administration of isosorbide dinitrate and constriction with ergonovine were not significantly different in patients with concentric and eccentric stenoses.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of theophylline, atenolol and their combination on myocardial ischemia in stable angina pectoris

The effects of theophylline (400 mg twice a day), atenolol (50 mg twice a day) and their combination on myocardial ischemia were studied in 9 patients with stable angina pectoris in a randomized, single-blind, triple crossover trial. Placebo was administered to the patients during the run-in and the run-off periods. A treadmill exercise test and 24-hour ambulatory electrocardiographic monitoring were obtained at the end of each treatment period. Compared with placebo, theophylline significantly improved the time to onset of myocardial ischemia (1 mm of ST-segment depression) from 7.8 +/- 3.7 to 9.5 +/- 3.7 minutes (p less than 0.03) and the exercise duration from 9 +/- 3.4 to 10.1 +/- 3.5 minutes (p less than 0.04). During atenolol and during combination treatment, the time to the onset of ischemia and the exercise duration were similar (10.8 +/- 4.2 and 11.2 +/- 3.2 minutes, 11.2 +/- 3.6 and 11.5 +/- 3.2 minutes, respectively) and longer than during theophylline administration (p less than 0.05). Ambulatory electrocardiographic monitoring showed that, during theophylline administration, the heart rate was higher than during placebo throughout the 24 hours (p less than 0.05). During atenolol and during combination treatment the heart rate was similar and in both cases lower than during placebo (p less than 0.05). Compared with placebo, theophylline decreased the total ischemic time from 97 +/- 110 to 70 +/- 103 minutes (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Similar time course of ST depression during and after exercise in patients with coronary artery disease and syndrome X

To assess whether the time course of ST segment depression differs in patients with coronary artery disease and patients with angina and normal coronary arteries, the exercise tests of 54 patients with documented coronary artery disease and 25 patients with syndrome X (angina, positive exercise test, no evidence of coronary artery spasm, and normal coronary arteries) were compared. All tests were performed with therapy withheld, using the modified Bruce protocol. In each test, time, heart rate and blood pressure were measured at the onset and at 1 mm of ST segment depression, and at peak exercise. Recovery (return of the ST segment to baseline +/- 0.2 mm) time was also assessed. Peak ST segment depression was similar in coronary artery disease and syndrome X patients (1.5 +/- 0.3 versus 1.6 +/- 0.4 mm). In 42 coronary artery disease patients, ST segment depression developed early (less than or equal to 6 minutes) during exercise; this was associated with a short recovery (less than or equal to 3 minutes) in 17 (40%) and with a long recovery (greater than 3 minutes) in 25 (60%) patients. In 17 patients with syndrome X, ST segment depression developed early; it was associated with a short recovery in six (35%) and with a long recovery in 11 (65%) patients. Late (greater than 6 minutes) onset of ST segment depression was observed in 12 coronary artery disease patients; of these, eight (67%) had a short recovery and 4 (33%) had a long recovery. Late onset of ST segment depression occurred in eight patients with syndrome X; six (75%) had a short recovery and two (25%) had a long recovery.(ABSTRACT TRUNCATED AT 250 WORDS)

Myocardial ischemia caused by distal coronary-artery constriction in stable angina pectoris

BACKGROUND

In patients with stable coronary artery disease, the ischemic threshold for the production of effort-related angina is often quite variable. Although this feature is commonly attributed to changes in the caliber of coronary arteries at the site of stenosis, it could also be caused by the constriction of distal vessels, collateral vessels, or both.

METHODS

In order to test this hypothesis, we studied 11 patients with stable angina, total occlusion of a single coronary artery that was supplied by collateral vessels, normal ventricular function, no evidence of coronary-artery spasm, and no other coronary stenoses. These conditions precluded the modulation of coronary flow by vasomotion at the site of the coronary stenosis.

RESULTS

The ischemic threshold--assessed by multiplying the heart rate by the systolic blood pressure at a 1-mm depression of the ST segment during exercise testing--increased by 19 percent after the administration of nitroglycerin (P less than 0.05) and decreased by 18 percent after the administration of ergonovine (P less than 0.01). Ambulatory electrocardiographic monitoring of the patients when not receiving treatment detected 73 ischemic episodes that, in keeping with the history, showed variations of 25 to 52 beats per minute in the heart rate at a 1-mm depression of the ST segment; 12 episodes of sinus tachycardia exceeded the lowest ischemic heart rate by a mean (+/- SD) of 22 +/- 13 beats per minute without ST-segment depression. Furthermore, 21 ischemic episodes occurred at a heart rate more than 25 beats per minute below that at a 1-mm depression of the ST segment during exercise testing. Delayed and reduced filling of collateral and collateralized vessels associated with depression of the ST segment similar to that observed during ambulatory monitoring was detected on angiographic evaluation after the intracoronary administration of ergonovine in three patients.

CONCLUSIONS

We propose that the constriction of distal coronary arteries, collateral vessels, or both may cause myocardial ischemia in patients with chronic stable angina.

Role of adenosine in pathogenesis of anginal pain

The intravenous infusion of adenosine provokes anginalike chest pain. To establish its origin, an intracoronary infusion of increasing adenosine concentrations was given in 22 patients with stable angina pectoris. During adenosine infusion, 20 patients had chest pain without electrocardiographic signs of ischemia. They all reported that the chest pain was similar to their usual anginal pain. In 10 of the 22 patients adenosine was also infused into the right atrium, but it never produced symptoms at the doses that had provoked chest pain during intracoronary infusion. In seven other patients, the intracoronary adenosine infusion was repeated after intravenous administration of aminophylline, an antagonist of adenosine P1-receptors. Aminophylline decreased the severity of adenosine-induced chest pain (assessed with a visual analog scale) from 42 +/- 22 to 23 +/- 17 mm (p less than 0.002). In the remaining five of the 22 patients, monitoring of blood oxygen saturation in the coronary sinus during intracoronary adenosine administration showed that maximum coronary vasodilation was achieved at doses lower than those responsible for chest pain. A single-blind, placebo-controlled, randomized trial of the effect of aminophylline on exercise-induced chest pain was also performed in 20 other patients with stable angina. Aminophylline, compared with placebo, decreased the severity of chest pain at peak exercise from 67 +/- 21 to 51 +/- 23 mm (p less than 0.02), despite the achievement of a similar degree of ST-segment depression. Finally, the effect of intravenous adenosine was compared in 10 patients with predominantly painful myocardial ischemia and in 10 patients with predominantly silent ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Spontaneous coronary artery spasm in variant angina is caused by a local hyperreactivity to a generalized constrictor stimulus

To assess whether spontaneous coronary artery spasm in patients with variant angina results from local coronary hyperreactivity to a generalized constrictor stimulus or from a stimulus generated only at the site of the hyperreactive segment, the behavior of spastic and nonspastic coronary segments was studied in six patients with variant angina in whom focal coronary spasm developed spontaneously during cardiac catheterization. None of the patients had critical (greater than 50% luminal diameter reduction) organic coronary stenoses. Coronary diameters were measured by computerized quantitative arteriography during control, spontaneous spasm and ergonovine-induced spasm and after intracoronary nitrates were given. During spontaneous spasm, the luminal diameter of spastic and both proximal and distal nonspastic coronary segments was significantly reduced from control values, 64.2%, 13.2% and 14.8%, respectively. Average diameter reduction of unrelated arteries was 12.3%. Ergonovine, which was also administered to four patients, provoked focal spasm at the same site as spontaneous spasm. During intravenous ergonovine, luminal diameter of spastic segments was reduced by 91.5%, that of nonspastic proximal segments by 17.8% and that of nonspastic distal segments by 11.5%. Luminal diameter of unrelated arteries during ergonovine-induced spasm was reduced by 17.7%. Constriction of spastic segments was greater during ergonovine-induced spasm (p less than 0.05), whereas the extent of diameter reduction of nonspastic segments was not significantly different during spontaneous spasm and ergonovine-induced spasm. Intracoronary isosorbide dinitrate dilated spastic and nonspastic coronary segments to a similar extent from control (20.7%, 18% and 16.5%, respectively; p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative effects of theophylline and isosorbide dinitrate on exercise capacity in stable angina pectoris, and their mechanisms of action

While the role of nitrates in the prevention and treatment of myocardial ischemia is well established, the use of theophylline, proposed almost a century ago, is still controversial. Also controversial is its mechanism of action, initially thought to be coronary dilation. In this randomized, single-blind study, the acute effects on exercise capacity of sublingual isosorbide dinitrate (10 mg) and of intravenous theophylline ethylenediamine (7 mg/kg) were assessed in 10 patients with chronic stable angina and positive exercise test. After the administration of theophylline, the time to onset of angina, the heart rate-blood pressure product at 1-mm ST-segment depression and the exercise duration were similar to that after isosorbide dinitrate administration (9.8 +/- 2.3 vs 9.3 +/- 1.7 minutes, 207 +/- 41 vs 207 +/- 48 beats/min.mm Hg.10(-2) and 10.8 +/- 2 vs 10.4 +/- 2 minutes, respectively). Both drugs significantly (p less than 0.001) improved all these parameters compared to the baseline exercise test. The effect of the 2 drugs on the diameters of angiographically normal segments of large epicardial coronary arteries was then assessed using computerized quantitative angiography in 10 other patients with stable angina. Whereas theophylline failed to increase the coronary diameters compared to that in the baseline angiogram (2.9 +/- 0.6 vs 2.9 +/- 0.6 mm, respectively), the subsequent administration of isosorbide dinitrate resulted in an increase up to 3.2 +/- 0.7 mm (p less than 0.02). Thus, in patients with stable angina, theophylline delays the onset of angina, increases the ischemic threshold and prolongs the exercise duration to the same degree as isosorbide dinitrate.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of diltiazem alone or with isosorbide dinitrate or with atenolol both acutely and chronically for stable angina pectoris

To establish the contribution of combination therapy in stable angina, the short- and long-term effects of diltiazem (120 mg and 360 mg/day, respectively), and the additive effects of sublingual isosorbide dinitrate, 10 mg, and atenolol, 100 mg, were studied in 11 patients with chronic stable angina using an open-label sequential design. All patients underwent exercise testing without therapy, and with each drug and their combinations. Exercise time and heart rate-blood pressure product were measured at 1-mm ST-segment depression, or at peak exercise if the test result was negative. Exercise time increased from a control value of 8.0 +/- 2.3 minutes (mean +/- standard deviation) to 11.4 +/- 2.4 minutes (p less than 0.0001) after the administration of isosorbide dinitrate, to 11.3 +/- 1.8 minutes (p less than 0.001) after short-term diltiazem and to 12.4 +/- 1.5 minutes (p less than 0.001) after long-term diltiazem. The rate-pressure product increased from a control value of 19,070 +/- 3,564 to 24,431 +/- 4,795 beats/min X mm Hg (p less than 0.0001) after isosorbide dinitrate, to 22,287 +/- 4,753 beats/min X mm Hg (p less than 0.01) after short-term diltiazem and to 21,812 +/- 3,976 beats/min X mm Hg (p less than 0.007) after long-term diltiazem. The addition of atenolol to long-term diltiazem significantly reduced the rate-pressure product compared with long-term diltiazem alone (21,812 +/- 3,976 vs 13,926 +/- 2,880 beats/min X mm Hg, (p less than 0.002), although there was no further significant increase in exercise time (12.4 +/- 1.5 vs 13.3 +/- 1.6 minutes).(ABSTRACT TRUNCATED AT 250 WORDS)

Ischemic threshold varies in response to different types of exercise in patients with chronic stable angina

The effects of different types of exercise on ischemic threshold were studied in 33 patients with chronic stable angina, documented coronary artery disease, and reproducible positive exercise test results. On average, ST segment depression developed at a significantly higher heart rate and rate-pressure product when the standard modified Bruce protocol was preceded by a warm-up period (113 +/- 13 vs 119 +/- 15 beats/min and 18,813 +/- 3682 vs 20,357 +/- 4227 beats/min X mm Hg, respectively; p less than 0.05 and less than 0.01). No significant changes were observed when the exercise was started abruptly. Analysis of results in individual patients showed that changes in rate-pressure product at 1 mm ST segment depression greater than or equal to 2000 beats/min X mm Hg developed with different types of exercise in 11 patients (group I), whereas in 22 patients little or no change occurred (group II). All patients also underwent exercise testing before and after 0.5 mg of sublingual nitroglycerin; improvement induced by nitroglycerin was significantly greater in group I than in group II (22 +/- 8 vs 8 +/- 9 beats/min and 4896 +/- 1998 vs 1064 +/- 2145 beats/min X mm Hg; p less than 0.01). Furthermore, isometric handgrip exercise carried out during angiography resulted in significant reduction of luminal diameter at the site of the stenosis of group I (1.22 +/- 0.39 vs 0.99 +/- 0.35 mm; p less than 0.01) but not in group II (1.12 +/- 0.22 vs 1.16 +/- 0.3 mm, p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Lack of evidence for alpha-adrenergic receptor-mediated mechanisms in the genesis of ischemia in syndrome X

Patients with syndrome X (typical angina pectoris, positive exercise tests [greater than or equal to 1 mm of ST-segment depression], no evidence of coronary spasm and angiographically normal coronary arteries) have a reduced coronary flow reserve due to inappropriate dilatation of small resistive vessels. To assess whether alpha-adrenergic mechanisms play a role in the genesis of ST-ischemic changes in syndrome X, 12 patients with this syndrome (2 men and 10 women, mean age 50 +/- 6 years) underwent exercise testing and 24-hour ambulatory electrocardiographic monitoring. They were done off treatment and after alpha blockade with prazosin and clonidine on 2 separate weeks. Despite treatment, all exercise tests remained positive and patients were stopped because of progressive angina pain. Compared to the off-treatment tests, exercise duration and heart rate-blood pressure product at 1 mm of ST-segment depression did not change significantly after prazosin (617 +/- 203 vs 663 +/- 203 seconds and 23,857 +/- 6,125 vs 22,098 +/- 4,816 beats/min X mm Hg, respectively) and clonidine (684 +/- 148 vs 649 +/- 80 seconds and 25,514 +/- 2,386 vs 24,567 +/- 2,001 beats/min X mm Hg, respectively). Ambulatory monitoring showed similar results regarding number of episodes of ST-segment depression greater than or equal to 0.1 mV during control and after prazosin (39 vs 38) or clonidine (26 vs 23) treatment. None of the 8 patients who also underwent provocative testing with phenylephrine had ischemic electrocardiographic changes; only 2 experienced chest pain during the test.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term variability of angina pectoris and electrocardiographic signs of ischemia in syndrome X

The long-term course of angina and the electrocardiographic signs of ischemia were assessed in 13 patients (10 women and 3 men, mean age 49 +/- 6 years) with typical angina pectoris, positive exercise tests, no evidence of coronary spasm and angiographically normal coronary arteries (syndrome X). Clinical and electrocardiographic parameters as well as results of exercise testing and 24-hour electrocardiographic monitoring were assessed at presentation and after a mean follow-up of 6.3 years (range 3 to 9). Mean number of anginal episodes and nitroglycerin consumption per week were similar at presentation and at the last follow-up. Furthermore, no significant difference was noted in heart rate-systolic blood pressure product at 0.1 mV of ST-segment depression (20,363 +/- 5,747 vs 21,649 +/- 5,687 beats/min x mm Hg), at angina (19,223 +/- 5,680 vs 20,126 +/- 6,023 beats/min x mm Hg) and at peak exercise (22,057 +/- 5,669 vs 22,868 +/- 6,122 beats/min x mm Hg). Time to 0.1 mV of ST-segment depression, to angina and to peak exercise was also similar (595 +/- 163 vs 631 +/- 184 s, 524 +/- 156 vs 571 +/- 168 s and 671 +/- 168 vs 718 +/- 186 s, respectively). The number of episodes of ST-segment depression greater than or equal to 0.1 mV during electrocardiographic monitoring was similar at presentation and follow-up (31 vs 25) as was the proportion of painful episodes (39 vs 36%). None of the patients developed major coronary events or cardiomyopathy during follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of theophylline on exercise-induced myocardial ischaemia

In a single-blind, placebo-controlled, randomised trial in 20 patients with stable angina pectoris, intravenous theophylline ethylenediamine (aminophylline), 7 mg/kg, increased the time to onset of angina by 46%, the heart-rate/blood-pressure product (an index of myocardial oxygen consumption) at 1 mm ST segment depression by 22%, and exercise duration by 24%. In a subsequent double-blind placebo-controlled trial in 8 patients a single oral dose of theophylline (375 mg) increased the time to onset of angina by 56%, the heart-rate/blood-pressure product at 1 mm ST segment depression by 22%, and the exercise duration by 35%. Infusion of theophylline ethylenediamine during angiography (10 patients) did not affect the diameter of epicardial coronary arteries. The beneficial effects of theophylline may be due to redistribution of coronary blood flow from non-ischaemic to ischaemic myocardium.

Adenosine-induced chest pain in patients with silent and painful myocardial ischaemia: another clue to the importance of generalized defective perception of painful stimuli as a cause of silent ischaemia

Adenosine is formed from adenosine triphosphate within the ischaemic cells from where it is released into the coronary circulation. Adenosine exhibits several cardiovascular effects which tend to protect the ischaemic myocardium. Based on the observation that in healthy volunteers the intravenous infusion of adenosine produces angina-like chest pain, it has been recently proposed that another cardioprotective action of this substance could be provocation of angina. If this is the case adenosine should not produce chest pain in patients with silent ischaemia. To test this hypothesis we infused this substance intravenously at increasing doses of 50, 100, 150, 200, 250 and 300 micrograms kg-1 min-1 in eight patients with silent ischaemia (group A). All of them developed ST depression (1.8 +/- 0.2 mm) during exercise testing and seven also during adenosine infusion (1.1 +/- 0.8 mm). However, none of the patients had chest pain during exercise while seven had chest pain during adenosine. We then infused adenosine in eight other patients (Group B) who had painful ischaemia and an exercise tolerance similar to that of Group A patients (time to 1 mm ST depression 8.6 +/- 2.7 min and 8.4 +/- 3 min, respectively, P = NS). Adenosine induced chest pain in all Group B patients. The time to pain onset during adenosine was similar in the two groups (9.3 +/- 2.3 min in Group B and 12.4 +/- 4.9 min in Group A).(ABSTRACT TRUNCATED AT 250 WORDS)

Pain threshold and tolerance in women with syndrome X and women with stable angina pectoris

A recent report showed that during Holter monitoring of patients with syndrome X (typical anginal pain, positive exercise test response [at least 0.1 mV of ST-segment depression], no evidence of coronary spasm and angiographically normal coronary arteries), 50% of episodes of ischemic ST-segment depression were painful. This proportion is considerably higher than that in patients with chronic stable angina, which is about 30%. A significantly lower threshold and tolerance to painful stimuli was seen in a group of patients with chronic stable angina in whom 50% of episodes were painful compared with a group in whom only 5% of episodes were silent. Hence, patients with syndrome X may have enhanced sensitivity to painful stimuli. To investigate whether this difference was due to a lower threshold for painful stimuli in general, 12 patients with syndrome X and 10 (age- and sex-matched) with chronic stable angina were studied using the same battery of painful stimuli. Patients with syndrome X had a significantly lower threshold and tolerance for forearm ischemia (-36%, p less than 0.05, and -40%, p less than 0.001) and electrical skin stimulation (-37%, p less than 0.01, and -35%, p less than 0.001); the cold pressor test did not show significant differences (-7%, p = 0.391, and -1%, p = 0.818). Thus, patients with syndrome X in this study had significantly lower threshold and tolerance values for forearm ischemia and for electrical skin stimulation. These differences in sensitivity to pain may partly explain a higher incidence of painful ischemic episodes detected by ambulatory electrocardiographic monitoring during unrestricted daily life.

Usefulness of Holter monitoring to improve the sensitivity of exercise testing in determining the degree of myocardial revascularization after coronary artery bypass grafting for stable angina pectoris

To assess whether Holter monitoring improves the sensitivity of exercise testing in identifying incomplete myocardial revascularization, both tests were performed in 45 patients from 3 to 5 months after elective coronary artery bypass grafting (CABG) for stable angina pectoris. Coronary angiography revealed incomplete revascularization in 26 patients. Six of these 26 had 52 episodes of ST-segment depression during Holter monitoring and myocardial ischemia during exercise testing. Their exercise capacity was significantly lower than that of 10 other patients in whom the results of exercise testing only were positive (heart rate at 0.1 mV ST-segment depression 112 +/- 9 vs 123 +/- 15 beats/min, p less than 0.001). In the other 10 patients with incomplete myocardial revascularization the results of both investigations were negative. The graft patency rate was lower in patients with a positive response to exercise testing than in those with a negative response (52% vs 71%, p less than 0.005). Myocardial revascularization was angiographically complete in 19 patients. In 18 of these 19 patients the findings of both investigations were negative; in 1 patient Holter monitoring revealed episodes of ST-segment elevation suggestive of variant angina. Thus, after CABG for stable angina pectoris the results of Holter monitoring do not improve the sensitivity of exercise testing in identifying patients with angiographically incomplete myocardial revascularization because findings are positive only in patients with low exercise capacity. Both tests fail to show evidence of myocardial ischemia in most patients with angiographically complete myocardial revascularization.

Induction of coronary artery spasm by a direct local action of ergonovine

To investigate whether ergonovine acts directly on coronary arteries or via remote neurohumoral reflexes, we administered small titrated increments of intracoronary ergonovine up to a maximum cumulative dose of 50 micrograms to 15 patients. In six patients with variant angina (group 1), ischemic electrocardiographic ST changes, angina, and localized coronary spasm (local coronary diameter reduction of 87.8 +/- 18.9% [mean +/- SD]) followed after 6 to 50 micrograms (mean 20.7) cumulative intracoronary ergonovine. In nine patients with atypical chest pain, normal baseline coronary arteriograms, and no evidence of variant angina (group 2), there was no ischemic ST segment change or localized coronary spasm after 6 to 50 micrograms (mean 31.6) intracoronary ergonovine. Coronary diameter of proximal vessels of patients in group 2 was reduced by 16.2 +/- 6.5% and did not differ from the response of nonspastic vessels of comparable size of group 1 (20.5 +/- 13.8%; p = .7). There was no significant difference in the median effective dose values in the dose-response curves of the spastic and nonspastic segments between groups 1 and 2. Ergonovine causes coronary spasm by a direct local effect, which seems to be caused by localized arterial hyperreactivity rather than supersensitivity. Intracoronary delivery may be safer than intravenous administration because negligible drug recirculation may prevent perpetuation of spasm and selective coronary administration can avoid branches with critical stenoses.

Local coronary supersensitivity to diverse vasoconstrictive stimuli in patients with variant angina

It has been shown in different groups of patients with variant angina that coronary spasm can be reproduced by physiologic maneuvers and pharmacologic agents. It is not known, however, to what extent different stimuli can induce spasm in the same patient. To investigate whether coronary arterial spasm results from specific abnormal agonist-receptor interactions or from a local nonspecific coronary supersensitivity to different stimuli, 28 patients with vasospastic angina were submitted to a series of diverse vasoconstrictive stimuli known to provoke coronary spasm. Ergonovine, hyperventilation, handgrip, cold pressor, and exercise-tests, were carried out in all 28 patients. In the last 15 patients histamine was also administered. Spasm was provoked by ergonovine in 96% of patients, by hyperventilation in 54%, by histamine in 47%, by exercise in 46%, and by the cold pressor and handgrip tests in 11% and 7%, respectively. No significant differences were found in the responses to provocative tests of patients with normal coronary arteries or nonsignificant stenoses and those with significant lesions. In the same individual, spasm was induced by at least two vasoconstrictive stimuli, although with a different mechanism of action, in 82% of patients and spasm was induced by three or more stimuli in 39%. Tests were repeated in at least 23 patients and short-term reproducibility paralleled sensitivity. These results suggest that in patients with variant angina, a local nonspecific supersensitivity rather than an abnormal specific agonist-receptor interaction plays a major role in the genesis of coronary arterial spasm.

Transient myocardial ischemia during daily life in patients with syndrome X

Nineteen patients with syndrome X (typical exertional angina, positive exercise test response [at least 0.1 mV of ST-segment depression], no evidence of coronary spasm and angiographically normal coronary arteries) underwent continuous 48-hour electrocardiographic (ECG) monitoring during unrestricted daily life. Fifty-eight ischemic episodes of at least 0.1 mV of ST-segment depression were observed in the same ECG leads that showed ST depression during stress testing: 28 (48%) were accompanied by anginal pain and 30 (52%) were asymptomatic. No significant differences were found between painful and silent ST-segment depression with regard to the number of episodes, their temporal distribution, magnitude, duration or heart rate (HR) at onset of ST-segment depression. In the minute preceding ischemic ST shifts, HR did not change in 33% of episodes or increased by less than 10 beats/min in 28%. HR at onset of ST depression was significantly lower during ambulatory ECG monitoring than during exercise testing (98 +/- 18 vs 117 +/- 18 beats/min, p less than 0.01). During ambulatory monitoring, 85 episodes of sinus tachycardia (exceeding by 10 to 80 beats/min the HR that triggered ischemia during exercise testing) occurred in the absence of angina or ST-segment shifts. The results of this study suggest that in patients with syndrome X, myocardial ischemia frequently develops during daily life; silent ischemia is an important component of this syndrome; and increased oxygen demand in the presence of impaired coronary vasodilatory capacity is not the only cause of myocardial ischemia. Active mechanisms that transiently reduce coronary flow may act and explain occurrence of angina at rest and with minimal exertion.

Variability of results during repeat exercise stress testing in patients with stable angina pectoris: role of dynamic coronary flow reserve

In some patients with stable angina, the variability of results during repeated exercise tests is higher than in others with similar symptoms. The aim of the study was to assess whether this difference can be explained by a different susceptibility of the coronary arteries to vasoconstrictor stimuli. Ten patients (group A) with stable angina, who developed myocardial ischemia (angina and ST segment depression greater than 0.1 mV) following ergonovine-induced coronary constriction, and 10 other patients (group B) with stable angina, but a negative ergonovine test result, were subjected to two treadmill exercise tests. The variability of heart rate and heart rate-blood pressure product at 0.1 mV ST segment depression was significantly higher in group A than in group B (12 +/- 4 vs 4 +/- 4 bpm, respectively, p less than 0.001 and 3366 +/- 1900 vs 930 +/- 960 bpm X mm Hg, respectively, p less than 0.005), such as the variability of heart rate-blood pressure product at the onset of angina (3887 +/- 2400 vs 1428 +/- 1800 bpm X mm Hg, respectively, p less than 0.04). The remaining exercise parameters were always more variable in group A than in group B, but these differences did not achieve statistical significance. Thus patients with stable angina who develop myocardial ischemia in response to ergonovine have a larger variability of results during repeat exercise testing. Such findings could be explained by an enhanced susceptibility to the coronary constrictor effects of exercise resulting in dynamic changes in coronary flow reserve.

Provocation of coronary spasm by dopamine in patients with active variant angina pectoris

The effects of dopamine on arteries are different depending on the dose, route of administration, and receptor population. Its administration can cause vasodilation by stimulation of dopaminergic receptors, vasoconstriction by stimulation of alpha-adrenergic and serotonergic receptors, and even spasm of cerebral arteries when given intracisternally in dogs. The ability of dopamine to provoke coronary spasm was assessed in 18 patients with active vasospastic angina in whom this amine was infused at rates of 5, 10, and 15 micrograms/kg/min for periods of 5 min each. The 12-lead electrocardiogram and blood pressure (cuff) were monitored throughout the whole test. In nine patients dopamine caused angina and ischemic electrocardiographic changes suggestive of coronary spasm: ST segment elevation in six patients and ST segment depression in the absence of important coronary stenoses in the remaining three. Infusion of dopamine was repeated during coronary angiography in three patients with positive test results: this provoked occlusive coronary spasm with ST segment elevation in two patients and nonocclusive spasm with ST segment depression in the remainder. In conclusion, infusion of dopamine provokes coronary spasm in a sizeable proportion of patients with active vasospastic angina. Its administration may be detrimental in patients susceptible to coronary spasm, such as those with acute myocardial infarction.

Increased uptake of 18F-fluorodeoxyglucose in postischemic myocardium of patients with exercise-induced angina

Regional myocardial perfusion and exogenous glucose uptake were assessed with rubidium-82 (82Rb) and 18F-2-fluoro-2-deoxyglucose (FDG) in 10 normal volunteers and 12 patients with coronary artery disease and stable angina pectoris by means of positron emission tomography. In patients at rest, the myocardial uptake of 82Rb and FDG did not differ significantly from that measured in normal subjects. The exercise test performed within the positron camera in eight patients produced typical chest pain and ischemic electrocardiographic changes in all. In each of the eight patients a region of reduced cation uptake was demonstrated in the 82Rb scan recorded at peak exercise, after which uptake of 82Rb returned to the control value 5 to 14 min after the end of the exercise. In these patients, FDG was injected in the recovery phase when all the variables that were altered during exercise, including regional myocardial 82Rb uptake, had returned to control values. In all but one patient, FDG accumulation in the regions of reduced 82Rb uptake during exercise was significantly higher than that in the nonischemic regions, i.e., the ones with a normal increment of 82Rb uptake on exercise. In the nonischemic areas, FDG uptake was not significantly different from that found in normal subjects after exercise. In conclusion, myocardial glucose transport and phosphorylation seem to be enhanced in the postischemic myocardium of patients with exercise-induced ischemia.

Mixed angina pectoris

Patients who present with episodes of angina caused both by an increase in oxygen demand and by transient impairment of supply have a mixed form of angina. Distinctive clinical features allow the classification of patients in everyday practice. At one end of the spectrum are patients who have angina only and always when they exercise beyond an essentially fixed level; their angina is fairly predictable and has been termed secondary angina. At the other end of the spectrum are patients who have a normal exercise tolerance but have angina at rest or during activities usually well tolerated that must be caused by a transient impairment of coronary blood flow; their angina is typically unpredictable and has been termed primary angina. We adopted the term primary to emphasize the possible existence of multiple causes of impairment of coronary flow, which together are to be contrasted with the traditional prevailing concept of angina being secondary to excessive increase in demand. In between these ends of the spectrum are most of the patients with angina pectoris encountered in clinical practice: they have a rather predictable ceiling of exercise that they cannot exceed without developing angina, but they also have a variable proportion of unpredictable anginal attacks that occur spontaneously or at levels of activity that are usually well tolerated. We introduced the concept of mixed forms of angina when we became aware that the same patient could experience angina both as a result of an excessive increase in myocardial demand, i.e., secondary angina, and as a result of the transient impairment of coronary blood flow supply, i.e., primary angina.

Different susceptibility to myocardial ischemia provoked by hyperventilation and cold pressor test in exertional and variant angina pectoris

Coronary constriction at the site of atherosclerotic stenoses has been suggested to play an important role in modulating the frequency of symptoms in patients with exertional angina. To investigate whether stimuli triggering coronary constriction have similar effects in patients with exertional and variant angina, responses to hyperventilation (HV) and cold pressor test (CPT) were evaluated. Twenty patients with chronic exertional angina, positive exercise test results and coronary heart disease were compared with 14 patients with variant angina and ST-segment elevation during an ergonovine test. In patients with exertional angina, the CPT produced diagnostic ST-segment depression in 6 of 20 patients (30%) at levels of rate-pressure product much lower than those during the exercise test; all patients had low effort tolerance and severe coronary artery disease. HV produced diagnostic ST-segment depression in only 1 of 20 patients (5%) (p less than 0.05 compared to that with CPT). Conversely, in patients with variant angina, HV produced ST-segment elevation in 11 of 14 patients (78%) and CPT produced elevation in only 2 of 14 (14%) (p less than 0.01). Thus, coronary constriction can provoke myocardial ischemia not only in patients with variant angina but also in some patients with exertional angina. Furthermore, the 2 groups of patients have a different susceptibility to stimuli known to produce coronary constriction.

Improved coronary supply: prevailing mechanism of action of nitrates in chronic stable angina

Exercise tolerance before and after sublingual isosorbide dinitrate (ISDN), 10 mg, was assessed in 217 consecutive patients with stable angina, positive exercise test, and angiographically proved coronary artery disease. In 65 patients (30%), ISDN prevented exercise-induced ST segment depression and/or increased exercise time to 1 mm ST segment depression (greater than or equal to 3 minutes), despite the significantly higher (greater than or equal to 25 X 10(2) increment) rate-pressure product attained (increased coronary reserve). On the contrary, in 40 other patients, exercise test remained positive, and neither time to 1 mm ST segment depression nor rate-pressure product increased significantly (fixed coronary reserve). The remaining 106 patients had an intermediate response. To assess the mechanisms underlying the beneficial action of nitrates, we further investigated 13 patients with increased coronary reserve (group 1) and five with fixed coronary reserve (group 2) by the exercise response to ISDN and verapamil, the changes in left ventricular volumes after ISDN and verapamil, the ECG response to intravenous ergonovine, and the changes in coronary stenosis severity following intravenous ergonovine and intracoronary nitrates. ISDN dramatically improved exercise capacity only in group 1 patients. However, it induced a significant reduction of left ventricular volumes in both groups (p less than 0.01). Ergonovine provoked angina and ST segment depression in 62% of group 1 patients and significantly increased the severity of their coronary stenoses (p less than 0.01). In all group 2 patients, ergonovine was negative, and no significant increase in stenosis severity was observed. Intracoronary nitrates reduced stenosis severity in group 1 (p less than 0.01) but not in group 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy of carvedilol (BM 14,190), a new beta-blocking drug with vasodilating properties, in exercise-induced ischemia

The exercise response to a single oral dose (25 mg) of a new beta-blocking agent that also has potent vasodilating properties, carvedilol (BM 14,190), was assessed in 15 patients with stable exertional angina, positive exercise test responses (greater than or equal to 1 mm of ST depression) and coronary artery disease. A single-blind, placebo-controlled, randomized, crossover design was used. Compared with placebo, 25 mg of carvedilol significantly reduced both heart rate (HR) and blood pressure (BP) at rest (p less than 0.01). After administration of carvedilol, 10 of 15 patients did not have angina at peak exercise (p less than 0.01) and 5 had ST shifts of less than 1 mm (p less than 0.05). Total exercise time and time to 1 mm of ST depression were prolonged and ST-segment depression at peak exercise was significantly reduced (p less than 0.01). Systolic BP was reduced both at peak exercise and at 1 mm of ST depression (p less than 0.05), whereas mean HR at peak exercise did not change significantly compared with placebo. Overall, mean HR-BP product at peak exercise was significantly reduced by carvedilol compared with placebo (p less than 0.05). However, 4 patients actually achieved a higher HR-BP product but did not have angina and had less ST depression (or no ST-segment shifts) at peak exercise. This indicates an increase in their coronary flow reserve. These results suggest that carvedilol is effective therapy for effort-induced angina, and this may be related to its combined beta-blocking and potent vasodilatory properties.

Myocardial ischemia during ergonovine testing: different susceptibility to coronary vasoconstriction in patients with exertional and variant angina

Coronary spasm is an accepted cause of transient myocardial ischemia in patients with variant angina; more recently it has been suggested that dynamic stenoses could also play an important role in the pathophysiology of exertional angina. To test this hypothesis we submitted 31 patients with histories typical of exertional angina to ergonovine testing and compared the electrocardiographic and clinical responses to those observed in seven patients with variant angina. All underwent bicycle ergometric exercise testing and coronary angiographic examination. For all tests, ST segment shifts of 0.1 mV or greater were considered to be diagnostic of myocardial ischemia. In patients with exertional angina, exercise testing produced diagnostic ST segment depression in 21 (68%). Ergonovine testing produced diagnostic ST segment depression in nine (29%). All nine had positive exercise test results and two- or three-vessel disease, yet the test was negative in seven other patients with positive exercise test results and similar angiographic findings. Conversely, in the seven patients with variant angina, results of exercise testing were positive in five (ST segment depression in two, ST elevation in three), while ergonovine produced ST segment elevation in all seven. Coronary angiographic examination showed normal arteries in two, one-vessel disease in four, and three-vessel disease in one. Results of all ergonovine tests were positive at values of rate pressure product much lower than those observed during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy of amiodarone during long-term treatment of potentially dangerous ventricular arrhythmias in patients with chronic stable ischemic heart disease

Amiodarone was administered orally to 30 patients with chronic stable coronary artery disease and severe ventricular arrhythmias. Control studies revealed frequent (more than 30/hr) ventricular premature beats (VPBs) (27 patients), bigeminy (21 patients), couples (29 patients), R-on-T phenomenon (14 patients), ventricular tachycardia (16 patients), and ventricular fibrillation (1 patient). Two 24-hour Holter recordings and stress tests were performed before treatment, and an average of 3.6 per patient were done during treatment. Amiodarone caused suppression of all ventricular arrhythmias in 13 (43%) of the 30 patients and suppression of all complex forms and greater than 90% reduction of VPB number in 14 patients (47%) during a follow-up of 12.4 months. The mean dose was 590 mg/day in the 27 responders and 300 mg/day in the three nonresponders. A similar antiarrhythmic response was observed during stress testing. One of the 30 patients died due to massive pulmonary embolism and no arrhythmias were detected. In addition, amiodarone suppressed the occurrence of anginal pain and effort-induced ST changes in 9 of 10 patients and in 11 of 13 patients, respectively. The rate-pressure product and peak heart rate were significantly reduced in all patients. Our results suggest that amiodarone may be ideally suited for treatment of ventricular arrhythmias and for possible prevention of sudden death in patients with ischemic heart disease.