Silent myocardial ischemia in patients with a defective anginal warning system

Low Levels of Vitamin D and Silent Myocardial Ischemia in Type 2 Diabetes: Clinical Correlations and Prognostic Significance

Vitamin D deficiency has a pathogenetic and prognostic role in coronary artery disease and a key role in pain transmission. Diabetic patients have a higher risk of silent myocardial ischemia (SMI) due to diabetic neuropathy. We evaluated the correlation between SMI and Vitamin D serum levels in type 2 diabetic patients and assessed whether SMI patients had a worse survival rate than their symptomatic counterpart. We enrolled 253 patients admitted in our Cardiology Unit and compared them with 50 healthy volunteers. We created three sub-groups: symptomatic MI group (125, 32.4%); SMI group (78, 25.7%), and no-MI group (50, 41.9%). 25(OH)D levels (nmol/L) were lower in the SMI group (34.9 ± 5.8) compared to those in the symptomatic MI (49.6 ± 6.1; p = 0.01), no MI (53.1 ± 6.2; p = 0.001), and control groups (62.1 ± 6.7; p = 0.0001). 25(OH)D levels predicted SMI in diabetic patients, with an inverted odds ratio of 1.11 (p = 0.01). Symptomatic MI group survival was higher than the SMI one (6-year survival rate: 83 vs. 69%; p = 0.01). Diabetic patients with SMI had a higher mortality risk and showed lower 25(OH)D levels than the symptomatic group. This suggests the crucial role that vitamin D has in the pathogenesis of SMI.

Mental status and pain perception during stressor tests in patients with coronary artery disease

Asymptomatic myocardial ischaemia is frequently observed in patients with coronary artery disease (CAD), both during daily life and during stressor tests. Psychological mechanisms seem to be involved in the lack of pain during myocardial ischaemia. The aim of this study was to verify in a selected population of CAD patients whether mental status might influence the pain perception during different stressor tests. The study population contained 73 male patients (mean age 52+/-8 years) with stable angina during daily life, reproducible exercise-induced myocardial ischaemia during ergometric stress test (EST) and angiographically documented CAD. All patients underwent cold pressor test (CPT), mental arithmetic stress test (MST), hyperventilation test (HT) and mental stress in association with cold pressor test (combined test, MST + CPT). During the stressor tests, myocardial ischaemia was induced in 15/73 (21%) patients by CPT, in 18/73 (25%) by MST, in 15/73 (21%) by HT and in 19/73 (26%) by MST + CPT. Out of the patients with stressor test-induced myocardial ischaemia, silent ischaemia was observed in 43/73 (59%) during EST, in 10/15 (67%) during CPT, in 16/18 (89%) during MST, in 7/15 (47%) during HT and in all patients during MST+CPT (100%). Among the ischaemic symptomatic patients during stressor tests, the lowest anginal pain intensity was experienced during MST (4.0+/-2.2) and the highest during EST, both at peak exercise and at the ischaemia threshold (6.6+/-2.9 and 5.9+/-2.7, respectively, p<0.05). During MST, the prevalence of silent ischaemia was higher than was observed during the other tests. All study patients remained asymptomatic when myocardial ischaemia was induced by MST + CPT. Even the intensity of CPT induced hand pain was significantly higher during CPT alone than during MST+CPT. These results confirm that mental status may influence pain modulation.

Silent ischemic interval on exercise test is a predictor of response to drug therapy: a randomized crossover trial of metoprolol versus diltiazem in stable angina

BACKGROUND AND HYPOTHESIS

There is no method available to predict the relative antianginal efficacy of beta blockers and calcium-channel antagonists. The present study was undertaken to assess the role of silent ischemic interval (SII) on exercise treadmill test (ETT) as a predictor of response to therapy with metoprolol and diltiazem in patients with stable angina.

METHODS

Thirty-four patients with stable angina were divided into two groups depending upon the presence or absence of an SII gap of at least 1 min between onset of ST depression and appearance of angina on ETT. Metoprolol (50-100 mg twice daily) and diltiazem (60-120 mg three times daily) were randomly assigned for 6 weeks to patients in each group, and then patients were crossed over for further 6 weeks after a washout period of 2 weeks. Antianginal efficacy was assessed by clinical and exercise parameters.

RESULTS

In patients with SII, the clinical responder rate was better with metoprolol than with diltiazem (90 vs. 60%, respectively), and on ETT, metoprolol produced significant improvement in the total exercise time (p< 0.01), time to 1 mm ST depression (p <0.01), time to angina (p <0.01), and a significant decrease in peak rate-pressure product (p<0.001), whereas diltiazem had no significant effect on exercise parameters. However, in patients without SII, metoprolol and diltiazem had a similar clinical responder rate (57%), and both produced a significant increase in total exercise time (p < 0.01), time to 1 mm ST depression (p < 0.01), and time to angina (p < 0.01). In addition, metoprolol had a significant effect on peak rate-pressure product (p < 0.001).

CONCLUSION

Silent ischemic interval on ETT can be a predictor of response to antianginal therapy in stable angina, as patients with SII respond better to metoprolol and those without SII respond equally to both metoprolol and diltiazem.

[Silent myocardial infarction]

INTRODUCTION

By autopsies of patients expired from different diseases not rarely chronic myocardial infarction is found, that was known before neither to patient nor to medical attendant (silent myocardial infarction) and is interpreted as incidental finding.

AIM

Study of frequency, role in expectation of life, diagnosis and prognosis of silent myocardial infarction in relation to localisation.

METHODS

Retrospective study and statistical analysis of 1568 autopsies performed during 10 years.

RESULTS

Acute or chronic myocardial infarction was found in 470 cases (30%), acute infarction in 177 cases (37%), 90% of which was diagnosed in vivo and patients died of infarction and its direct complications. In 293 cases (63%) chronic myocardial infarction was found, 109 cases (37%) were known and 184 cases (63%) were silent myocardial necrosis, the ratio of female/male patients was nearly the same (90/94 persons). 97 patients (32%) with chronic myocardial infarction died of cardiac cause - mostly in cardiac failure -, 196 (68%) of extracardiac cause, most of them of stroke, predominantly the patients with inferior infarction.

CONCLUSION

Considering the silent causes, the myocardial infarction is more frequent and has better prognosis, than it is known from epidemiological data without autopsies, because 42% of these patients dies of extracardiac diseases, and the continuity of life is not shorter, than by patients without myocardial infarction. Knowledge of silent infarction gives possibility to estimate the physical charge of patients, their treatment and to prevent recurrence.

Silent myocardial ischemia in diabetic and nondiabetic patients with coronary artery disease

BACKGROUND

Patients with diabetes mellitus are at increased risk for CAD; silent ischemia is reported to be frequent in diabetic populations. The aim of the present study was to evaluate the prevalence of silent ischemia in diabetic and nondiabetic patients with assessed CAD.

METHODS AND RESULTS

We recruited a total of 618 patients with CAD: 309 were consecutive diabetic patients and 309 were age- and gender-matched nondiabetic patients. Myocardial ischemia was evaluated both during daily life and during exercise testing. Angina pectoris during daily life was more frequent in diabetic than in nondiabetic patients (80% vs. 74%, P<0.05). The anginal pain intensity either during daily life or acute myocardial infarction (MI), the prevalence of a previous MI, the extent of CAD and ergometric parameters were similar in diabetics and nondiabetics. Silent ischemia during exercise was documented in 179 (58%) diabetics and in 197 (64%) nondiabetics (nonsignificant, ns). Both diabetics and nondiabetics with silent exertional myocardial ischemia differed from symptomatic subjects in higher heart rate values (P<0.01), systolic blood pressure (P<0.01), rate-pressure product (P<0.001), work load (P<0.01) and maximum ST-segment depression at peak exercise (P<0.05).

CONCLUSIONS

The incidence of silent myocardial ischemia during exercise was similar in diabetic and nondiabetic CAD patients. Surprisingly, diabetics showed a higher prevalence of angina pectoris during daily activity than nondiabetics. A significant association between the presence of symptoms during daily life and exercise was observed in both groups. Our results may contribute to the planning of the clinical management of diabetic CAD patients and confirm the individual attitude to pain of CAD patients independent of the presence of diabetes.

Use of intracoronary electrocardiography for detecting ST-T, QTc, and U wave changes during coronary balloon angioplasty

Intracoronary electrocardiography (IC-ECG) is a more sensitive method than surface ECG to detect electrical changes during percutaneous transluminal coronary angioplasty (PTCA). It also provides direct monitoring of ST-T segment, QTc intervals, and U-wave genesis during balloon inflation. These changes are reflective of myocardial ischemia. The authors studied the effect of transient myocardial ischemia on ST-T segment, QTc intervals, and U-wave appearance by comparing standard and perfusion balloon angioplasty. PTCA of left anterior descending artery was performed in 14 patients using the standard balloons and in 11 patients using the perfusion balloons. Patients with perfusion balloon angioplasty had less ST-T elevation (0.15 +/- 0.05 mV versus 1.04 +/- 0.19 mV, P < 0.001), less QTc-shortening intervals (0.01 +/- 0.02 seconds versus -0.05 +/- 0.04 seconds, P < 0.001), and less positive U waves (two versus nine). The authors concluded that balloon angioplasty with perfusion balloons is associated with less ischemia as reflected by ST-T, QTc-shortening intervals, and U-wave changes. There was more positive U-wave appearance with the standard balloon angioplasty, which implies more ischemia. In addition, QTc-shortening intervals are associated with the development of U waves during standard balloon angioplasty. These findings suggest that IC-ECG is a sensitive tool in detecting myocardial ischemia. IC-ECG may also help to clarify the nature of chest pain during PTCA in some patients. Like QT dispersion (QTd), QTc-shortening intervals and new U waves can have prognostic implications and additional studies are needed to define this role.

Prevalence, predisposing factors, and prognosis of clinically unrecognized myocardial infarction in the elderly

OBJECTIVES

This study was designed to determine the prevalence of unrecognized myocardial infarction (UMI), as well as risk factors, and to compare prognosis after detection of previously UMI to that after recognized myocardial infarction (RMI).

BACKGROUND

Past studies revealed that a significant proportion of MIs escape recognition, and that prognosis after such events is poor, but the epidemiology of UMI has not been reassessed in the contemporary era.

METHODS

The Cardiovascular Health Study (CHS) database, composed of individuals > or =65, was queried for participants who, at entry, demonstrated electrocardiographic evidence of a prior Q-wave MI, but who lacked a history of this diagnosis. The features and outcomes of this group were compared to those of individuals with prevalent RMI.

RESULTS

Of 5,888 participants, 901 evidenced a past MI, and 201 (22.3%) were previously unrecognized. The independent predictors of UMI were the absence of angina and the absence of congestive heart failure (CHF). Six-year mortality did not significantly differ between the two groups.

CONCLUSIONS

1) In the elderly, UMI continues to represent a significant proportion of all MIs; 2) associations with angina and CHF may reflect complex neurological issues, but they also may represent diagnosis bias; 3) these individuals can otherwise not be distinguished from those with recognized infarctions; and 4) mortality rates after UMI and RMI are similar. Future studies should address screening for UMI, risk stratification after detection of previously UMI, and the role of standard post-MI therapies.

Symptomatic myocardial ischemia and everyday life: implications for clinical use of interactive monitoring

In coronary heart disease (CHD), pathological myocardial ischemic changes do not always occur with the symptom of heart pain. Methodological problems make it difficult to examine the factors that influence silent and symptomatic myocardial ischemia in everyday life. This study uses a computer-assisted monitoring system with an interactive Holter ECG, an actometer, and an electronic diary. Self-report measurements indicate that symptomatic patients tend toward increased neuroticism, whereas asymptomatic patients engage in beneficial and active coping skills more frequently. The results of the monitoring study demonstrate the same degree of ischemia in silent and symptomatic episodes. However, these episodes show differences in certain psychological context variables. Symptomatic episodes are linked to high subjective strain and severe tension. Because angina pectoris is not a reliable warning signal of myocardial ischemia, the use of the interactive monitoring system is recommended for educating CHD patients on how to cope with excessive strain in everyday life.

Visceral chest pain in unstable angina pectoris and effects of transcutaneous electrical nerve stimulation. (TENS). A review

A substantial proportion of patients with chest pain referred to hospital, show signs of coronary artery disease. Anginal pain could be conceptualized as a warning signal for coronary artery disease and impending death. But, for many reasons this theory is partly disputed. Firstly, not all ischemic episodes are accompanied by anginal pain (silent ischemia). Secondly, chest pain indistinguishable from true angina pectoris may be the result of other abnormalities of thoracic viscera. Nevertheless acute severe cardiac ischemia often gives rise to anginal chest pain. Unstable angina pectoris is carrying a higher risk for future events in spite of intensive medical treatment. A special problem are patients awaiting coronary intervention because of severe ischemia and maximum medical treatment, who experience ischemic pain. New treatment regimens are needed for these patients. This review discusses the symptom of visceral pain from the heart, angina pectoris, its relation to ischemia and unstable angina pectoris. It also addresses the role of afferent nerve stimulation (transcutaneous electrical nerve stimulation, TENS) in the treatment of severe angina pectoris as well as recent findings of TENS applicability in unstable angina.

Treatment with enalapril modifies the pain perception pattern in hypertensive patients

The cardiovascular system shares numerous anatomic and functional pathways with the antinociceptive network. The aim of this study was to investigate whether angiotensin-converting enzyme (ACE) inhibitor treatment could affect hypertension-related hypalgesia. Twenty-five untreated hypertensive patients, together with a control group of 14 normotensive subjects, underwent dental pain perception evaluation by means of a pulpar test (graded increase of test current applied to healthy teeth). After the evaluation of the dental pain threshold (occurrence of pulp sensation) and tolerance (time when the subjects asked for the test to be stopped), all the subjects underwent a 24-hour ambulatory blood pressure monitoring. The hypertensive group then was treated with 20 mg/d enalapril, whereas the normotensive subjects remained without any treatment. After a time interval of 6+/-2 months, the dental pain sensitivity was retested in all the subjects, and ambulatory blood pressure was recorded during treatment in the hypertensive patients. At the first assessment, hypertensive patients showed a higher pain threshold than normotensive subjects (P<.001). On retesting of pain sensitivity in hypertensive patients, a significant decrease of both pain threshold and tolerance, leading to their normalization, was observed during treatment (P<.001 and P<.005, respectively), in the presence of reduced 24-hour and office blood pressure values. A slight, though significant, correlation was observed between variations in pain tolerance and baseline blood pressure changes occurring during treatment. During follow-up, the normotensive subjects did not show any significant pain perception or office blood pressure changes. Hypertension-related hypalgesia was confirmed. Mechanisms acting both through lowering of blood pressure and specific pharmacodynamic properties may account for the normalization of pain sensitivity observed in hypertensive patients during treatment with ACE inhibitors.

Myocardial Ischemia During Weaning From Mechanical Ventilation

Coronary artery disease (CAD) affects more than 11 million Americans and is the leading cause of death in the United States. Both CAD and critical illness occur more frequently in older patients. However, the contri bution of myocardial ischemia to morbidity and mortal ity in critically ill patients has not been well studied. Weaning from mechanical ventilation is expected to be a period of significant cardiopulmonary stress during recovery from critical illness. However, few studies have examined the epidemiology of and clinical risk factors for weaning-related myocardial ischemia. In this review, the pathophysiology of myocardial ischemia during weaning is outlined, the studies examining this entity are analyzed, and a systematic approach to diagnosis and management is suggested.

Susceptibility to pain in hypertensive and normotensive patients with coronary artery disease: response to dental pulp stimulation

An association between a decreased responsiveness to varying painful stimuli and arterial hypertension both in animals and in humans has been documented. The relationship between essential hypertension and silent myocardial ischemia in coronary artery disease (CAD) populations is not well understood. The aims of this study in CAD patients with and without essential hypertension were (1) to determine dental pain threshold and reaction to tooth pulp stimulation and (2) to ascertain whether hypertensive CAD patients differ from normotensive ones in reactivity to pain. This study involved 182 patients who were affected by mild and moderate hypertension (G1) and 174 normotensive patients (G2). The inclusion criteria were reproducible exercise-induced myocardial ischemia, CAD documented at angiography, and dental formula suitable for pulp test. All patients underwent an ergometric stress test, coronary angiography, and pulp test. Our CAD hypertensive patients showed a lower prevalence of angina during daily life (64.8% in G1 versus 81.6% in G2, P<.05) and a higher incidence of exercise-induced silent myocardial ischemia (60.4% in G1 versus 48.8% in G2, P<.05) than the normotensive group. The mean anginal pain intensity, which was suffered both during spontaneous transitory episodes of ischemia and/or during acute myocardial infarction, was significantly lower in G1 than in G2 patients (P<.05). During pulp test, 31.8% of G1 and 13.7% of G2 referred no symptoms, even at the highest current intensity of 500 mA. The hypertensive patients with symptoms during pulp test had a higher mean dental pain threshold and lower mean threshold reaction and maximal reaction than did the normotensive symptomatic ones. In patients of both groups, a positive correlation between the mean maximal reaction during pulp test and the prevalence of angina during daily life was also found. In conclusion, patients with CAD and essential hypertension differ from normotensive CAD patients in reactivity to pain. Significantly higher pain thresholds and lower reactions to tooth pulp stimulation characterized patients with increased blood pressure values.

Effect of type A behavioral counseling on frequency of episodes of silent myocardial ischemia in coronary patients

Thirteen of 32 patients with coronary heart disease who also exhibited symptoms and signs of severe time urgency and hostility (the two overt components of type A behavior [TAB]) were found to exhibit multiple episodes of silent myocardial ischemia over a 48-hour period of Holter monitoring as indicated by electrocardiogram ST depressions. Ten of these 13 patients were given 14 months of TAB counseling in an attempt to diminish the intensity of their time urgency and hostility. The remaining three patients served as controls. After counseling, the intensity of the time urgency and hostility of the 10 counseled patients diminished 53% and 59%, respectively, as measured by the videotaped clinical examination. The time urgency and hostility of the three uncounseled control patients did not significantly change. The mean frequency of ischemic episodes in the 10 patients who received TAB counseling significantly declined from an initial 6.6 to 3.1 ischemic episodes per 24 hours. However, the mean frequency of ischemic episodes did not significantly decline in 2 of the 3 uncounseled patients. The third uncounseled patient developed a conduction defect in the 14-month interlude, making an analysis of his repeat 48-hour electrocardiogram for episodes of ST depression impossible.

Susceptibility to pain during coronary angioplasty: usefulness of pulpal test

OBJECTIVES

This study in patients with coronary artery disease (CAD) sought to 1) determine the dental pain threshold and reaction to tooth pulp stimulation; 2) correlate the clinical, ergometric and angiographic features of patients with and without pain during percutaneous transluminal coronary angioplasty (PTCA) to pulpal test response; 3) verify whether reactivity to dental pulp stimulation could help to identify patients particularly prone to perceiving angina during myocardial ischemia.

BACKGROUND

Silent myocardial ischemia is frequently observed in patients with CAD. Higher pain thresholds have been documented in asymptomatic subjects, suggesting a generalized hyposensitivity to pain.

METHODS

Eighty-six consecutive male patients with reproducible exercise-induced myocardial ischemia and CAD documented by angiography underwent PTCA. A pulpal test was performed in all patients by means of an electrical tooth pulp stimulator.

RESULTS

Seventy-one patients (82.6%) with and 15 (17.4%) without angina during daily life were studied. During the pulpal test, 57 patient (66.2%) reported dental pain, whereas 29 (33.7%) were asymptomatic, even at maximal stimulation of 500 mA. The study cohort was classified into two groups according to the presence (58 patients [group 1]) or absence (28 patients [group 2]) of angina during myocardial ischemia induced by PTCA. Ergometric variables, extent of CAD, presence of ST segment elevation during PTCA, number of inflations, inflation time and maximal inflation pressure were similar in the two patient groups. Dental pain was provoked by pulpal test in 81% of patients with and 36% of patients without symptoms during PTCA (p = 0.0004). The absence of dental pain even at maximal tooth pulp stimulation (500 mA) was observed in 11 (18.9%) patients in group 1 and 18 (64.2%) in group 2. Patients who were asymptomatic during PTCA had a higher mean dental pain threshold, lower mean threshold reaction and lower mean maximal reaction than those who were symptomatic during both PTCA and the pulpal test.

CONCLUSIONS

A correlation between the prevalence of symptoms during pulpal test, daily life, exercise-induced myocardial ischemia and PTCA was found. A higher dental pain threshold and lower reactivity characterized those subjects who were prone to silent ischemia both during daily life and during PTCA. Ergometric variables, extent of CAD and techniques used during PTCA were unrelated to the tendency to perceive pain during myocardial ischemia. Response to the pulpal test and the presence of symptoms during daily life were highly related to the presence of angina during PTCA.

Contemporary approaches in medical management of patients with stable coronary artery disease

CAD continues to be the principal cause of mortality in the United States, and the largest group of patients with CAD are those with stable angina. Among this group of patients, the most common manifestation of CAD is presence of transient episodes of myocardial ischemia. The presence of transient ischemia and not the severity of angina has been found to be associated with poor clinical outcome in patients with stable CAD. As part of a global treatment strategy for patients with stable CAD, changes in lifestyle and modification of coronary risk factors should be emphasized as an integral part of treatment. Conventional antianginal therapy is quite effective in controlling anginal attacks. Currently, several drugs and therapeutic strategies are available for the treatment of patients with angina (see Table 5). Nitrates are highly effective antianginal drugs with complex beneficial actions in patients with CAD, but their usefulness is limited by development of tolerance during long-term use. When clinically indicated, the use of nitrates should be supplemented with another longer-acting antianginal drug, such as a beta-blocker or a calcium channel blocker. Based on the available data, beta-blockers, when tolerated, seem to be the most effective antianginal drugs for most patients with stable CAD. Beta-blockers are also the most effective anti-ischemic drugs that reduce the magnitude of myocardial ischemia detected during routine daily activities. Calcium channel blockers are also effective vasodilators and good antianginal drugs. The clinician should become familiar with the different actions that this heterogeneous group of drugs has on the heart and vessels. This knowledge allows the clinician to choose the appropriate combination of different antianginal drugs for patients on an individualized basis. It is also critical to develop the treatment strategy by carefully taking into account other associated medical conditions that are frequently encountered in patients with CAD.

Magnitude of myocardial dysfunction is greater in painful than in painless myocardial ischemia: an exercise echocardiographic study

OBJECTIVES

This study sought to assess the presence and extent of inducible myocardial dysfunction during painful and painless (silent) myocardial ischemia in a homogeneous patient cohort with coronary artery disease and no previous myocardial infarction.

BACKGROUND

The functional significance of painless versus painful demand-driven ischemia remains controversial, with conflicting results in published reports regarding the amount of myocardium in jeopardy.

METHODS

Exercise echocardiography was performed in 89 patients (mean [+/- SD] age 59.3 +/- 8.2 years) with significant coronary artery disease and positive exercise stress test results. Patients were taking no antianginal medications and were classified into painless and painful cohorts after the outcome of a symptom-limited treadmill exercise test. No patients had previous coronary artery bypass surgery. Images were acquired in digital format before and immediately after treadmill exercise testing.

RESULTS

Fifty-eight patients had painful and 31 painless myocardial ischemia. Clinical and demographic characteristics as well as coronary artery anatomy were similar in both groups. Patients with painless ischemia achieved better exercise performance with greater exercise duration (p < 0.001) and higher maximal rate-blood pressure product (p < 0.001) than those with painful ischemia. New wall motion abnormalities were seen in 54 patients (93%) with painful versus 17 (55%) with painless ischemia (p < 0.001). Total ischemic score was greater in patients with painful than in those with painless ischemia (15.9 +/- 3.7 vs. 12 +/- 1.4, p < 0.001, respectively), with a greater number of ischemic myocardial segments in painful than in painless ischemia (101 [16%] vs. 21 [6%], p < 0.001, respectively).

CONCLUSIONS

Patients with painless ischemia frequently have regional myocardial dysfunction on exertion detected by echocardiography, but painful episodes are accompanied by a greater magnitude of myocardial dysfunction.

Prognostic significance of silent ischemia

This study examined the prognostic predictors in 521 patients with angiographic evidence of coronary artery disease (CAD). All patients underwent exercise single-photon emission computed tomographic thallium imaging. The patients were divided into those with symptomatic ischemia defined as reversible thallium defects, S-T segment depression (or both) and angina during exercise (n = 210, group 1), and silent ischemia defined as thallium defects or ST segment depression (or both) but no angina during exercise (n = 311, group 2). During a mean follow-up of 24 +/- 21 months, there were 30 cardiac events (death or nonfatal myocardial infarction). The extent of CAD (2.0 +/- 0.8 diseased vessels in group 1 and 2.1 +/- 0.8 diseased vessels in group 2), the left ventricular ejection fraction, the extent of perfusion abnormality (21% +/- 11% in group 1 and 24% +/- 12% in group 2), and the peak heart rate and double product were similar in the two groups. Survival analysis showed no significant difference in the event-free survival in patients with symptomatic or silent ischemia. The 2-year event-free survival rate was 95% in group 1 and 94% in group 2 (difference not significant). The extent of perfusion abnormality and history of diabetes mellitus were the most important predictors of events. Thus the prognosis of medically treated patients with CAD is comparable in those patients with silent or symptomatic ischemia and is dependent on the extent of myocardium at risk rather than presence or absence of angina pectoris during exercise.

Beta-endorphins during coronary angioplasty in patients with silent or symptomatic myocardial ischemia

OBJECTIVES

The aims of this study were to correlate beta-endorphin plasma levels and anginal pain in patients with ischemia induced by percutaneous transluminal coronary angioplasty and to detect eventual endorphin variations during balloon occlusion.

BACKGROUND

The opioid system appears involved in the absence of pain occurring in silent myocardial ischemia.

METHODS

Beta-endorphin plasma levels were measured 24 h before, just before, during and after coronary angioplasty (performed on the left anterior descending artery) in 53 men with documented coronary artery disease and exercise-induced myocardial ischemia.

RESULTS

Group 1 (33 patients) reported symptoms; group 2 (20 patients) was asymptomatic during angioplasty. In these patients, the prevalence of exercise-induced silent ischemia was 57%. The occurrence of angina during exercise or angioplasty was related to the frequency of angina during daily life when patients were subgrouped. The severity and distribution of coronary artery disease did not differ between the two groups. During angioplasty, the number of balloon inflations and the inflation time and pressure were similar in symptomatic and asymptomatic patients. In each group, no short-term variability of baseline beta-endorphin plasma levels was observed during 2 consecutive days. Corresponding beta-endorphin plasma levels (at baseline and during and after angioplasty) were significantly higher in Group 2. During balloon occlusion, the levels decreased significantly in the symptomatic group at the onset of angina but remained stable in the asymptomatic group.

CONCLUSIONS

Methodologic variables and the severity of coronary artery disease did not influence the presence of symptoms during angioplasty-induced ischemia. Beta-endorphin plasma levels were higher and more stable in patients with silent ischemia during angioplasty, suggesting that opiate levels and their variation during ischemia are associated with individual attitude toward anginal pain.

Silent myocardial ischemia

The documentation of abnormalities related to myocardial ischemia, whether symptomatic or silent, is of central importance. Whenever this information is available, it should be used in the overall assessment of the patient at risk for adverse outcome. The level of concern for treatment of CAD should be based on the risk implications associated with the ischemia-related abnormalities detected during objective testing rather than on the presence or absence of pain. The exercise stress test is still the single most useful test to begin the evaluation of a patient with an analyzable ST segment. In persons suspected of having CAD, the detection of ischemic-type ST-segment depression, at a low workload (e.g., < 120 beats/min or < 6.5 METS) of > 2 mm magnitude or persisting for more than 6 min implies high risk for adverse outcome. Asymptomatic ischemia during everyday activities, detected by Holter monitoring, in the high-risk patient, most probably adds additional risk beyond the risk of an abnormal stress test alone. Left ventricular imaging by two-dimensional echocardiography, RNA, angiogram, vest, etc, showing an ejection fraction > or = 40%, reversible wall motion abnormalities in multiple regions and redistribution defects or a failure to increase ejection fraction during exercise even if the patient remains asymptomatic, also imply high risk. The presence of any of these abnormal findings, regardless of symptoms, should therefore prompt as high a degree of concern as with ischemia-related signals associated with pain. Thus any therapy chosen should be directed toward elimination of transient ischemia, not just relief of symptoms that may or may not be ischemia related. If this course is chosen, the efficacy of the therapeutic regimen and possible progression of CAD should be assessed with follow-up testing for ischemia. We believe that risk factor modification and aspirin should be considered for most, if not all, patients in whom ischemia, silent or symptomatic, is suspected or detected. If symptoms or ischemia suggesting low risk is present, anti-ischemic medical therapy may be considered, but follow-up is advised. If a high-risk ischemic signal, even without symptoms, is detected, medical therapy should be used to attempt to modify the signal. If the ischemic signal suggesting high risk persists despite medical therapy, revascularization should be considered. Until additional data from large clinical trials are available, this approach appears to have the greatest likelihood of modifying the adverse outcome of CAD.

Prognosis for patients with initially suspected acute myocardial infarction in relation to presence of chest pain

In all 4,232 patients admitted to a single hospital during a 21-month period due to initially suspected acute myocardial infarction (AMI), the prognosis and risk factor pattern were related to whether patients had chest pain or not. Symptoms other than chest pain that raised a suspicion of AMI were mainly acute heart failure, arrhythmia, and loss of consciousness. In 377 patients (9%) symptoms other than chest pain raised an initial suspicion of AMI. These patients developed a confirmed infarction during the first three days in hospital with a similar frequency (22%) as compared with patients having chest pain (22%). However, patients with "other symptoms" had a one-year mortality of 28% versus 15% for chest pain patients (p less than 0.001). Patients with "other symptoms" more often died in association with ventricular fibrillation and less often in association with cardiogenic shock as compared with chest pain patients. Among the 921 patients who developed early AMI, 64 (7%) had symptoms other than chest pain. They had a one-year mortality of 48% versus 27% for chest pain patients (p less than 0.001). We conclude that in a nonselected group of patients hospitalized due to suspected AMI, those with symptoms other than chest pain have a one-year mortality, which is nearly twice that of patients with chest pain.

Silent myocardial ischemia in men with systemic hypertension and without clinical evidence of coronary artery disease

The prevalence, characteristics and circadian pattern of silent myocardial ischemia, and its association with ventricular arrhythmias was studied in hypertensive men aged 35 to 70 years (mean 61) without clinical cardiac disease. Participants were withdrawn from diuretic treatment and received 1 month of oral electrolyte repletion with 40 mmol of potassium chloride, and 400 mg of magnesium oxide daily. Twenty-four-hour Holter monitoring was then performed. Episodes of silent myocardial ischemia occurred in 50 of 186 men (27%) and lasted from 2 to 289 minutes (mean 30 and median 18). Statistical analysis comparing the interval from midnight to 6 A.M. with each of the other three 6-hour time intervals revealed that participants were less likely to have silent myocardial ischemia in this period (p less than 0.01 for each comparison) than at other times of the day. There was little difference in the proportion of men with a frequent or complex ventricular arrhythmia during the entire day or within 1 hour of the silent myocardial ischemic episode (or during a comparable time period) comparing those with to those without silent myocardial ischemia. These findings indicate that silent myocardial ischemia occurs in approximately 25% of an older population of hypertensive men without history of symptomatic cardiac disease. The circadian pattern of frequency of silent ischemic events in men free of clinical cardiac disease is similar to that reported for patients with cardiac disease and coincides with that reported for sudden death. There was no significant association between silent myocardial ischemia and ventricular arrhythmias.

Asymptomatic myocardial ischemia during percutaneous transluminal coronary angioplasty and importance of prior Q-wave infarction and diabetes mellitus

Eighty-eight patients undergoing percutaneous transluminal coronary angioplasty (PTCA) of 100 stenoses were studied for the presence of factors deemed significant in the etiology of silent myocardial ischemia. Thirty-two patients were asymptomatic during balloon dilations of 36 arteries, and 56 patients had angina during PTCA of 64 arteries. There were no differences in age, sex, prior anginal history, antianginal regimen, extent of coronary artery disease and number or duration of inflations between the 2 study groups. Previous infarction (33 vs 12%, p less than 0.02), Q waves in the target area (31 vs 7%, p less than 0.005) and diabetes mellitus (36 vs 17%, p less than 0.05) were present more often in the asymptomatic group. Sixty-four% of all asymptomatic patients had either diabetes or previous infarction in the target territory. Collateral circulation was more frequent in asymptomatic patients, probably reflecting the ability of collateral arteries to ameliorate ischemia. During 2-vessel PTCA, patients without angina during dilation of only 1 of the 2 treated arteries (discordant responders) had previous infarction in that artery's territory (5 of 5, 100%), whereas patients without previous infarction were either symptomatic or asymptomatic (concordant responders) during PTCA of both arteries. This study shows that asymptomatic ischemia occurs frequently during PTCA in patients with symptomatic coronary disease. Prior Q-wave infarction and diabetes mellitus are important, independent factors associated with painless ischemia. It is suggested that infarction produces a localized dysfunction of afferent cardiac pain fibers, whereas diabetes can cause a global cardiac sensory neuropathy.

Aging, autonomic function, and the perception of angina

OBJECTIVE

To determine the effects of age and autonomic function on the perception of angina.

DESIGN

Prospective evaluation of the relations between anginal perceptual threshold, autonomic function, and systolic blood pressure in patients with symptomatic coronary artery disease. Statistical analysis was by non-parametric techniques.

SETTING

Cardiology departments of a district general hospital and a post-graduate teaching centre.

SUBJECTS

82 non-diabetic men with typical exertional angina and coronary artery disease confirmed by arteriography (n = 64) or a history of Q wave infarction (n = 18).

MAIN OUTCOME MEASURES

Age, anginal perceptual threshold, autonomic function, and blood pressure. Anginal perceptual threshold was defined as the time from onset of 0.1 mV ST depression to the onset of angina during treadmill stress testing. Autonomic function was measured as the ratio of peak heart rate during the Valsalva manoeuvre to the minimum rate after release.

RESULTS

Anginal perceptual threshold showed a weak but significant correlation with age, with older patients tending to have a longer interval between the onset of ST depression and the onset of angina. Comparison of patients in the upper and lower quartile age ranges showed a difference of 50 seconds between median threshold measurements. Blood pressure and heart rate responses to the Valsalva manoeuvre also correlated with age, but neither variable correlated with the anginal perceptual threshold.

CONCLUSIONS

In non-diabetic men with coronary artery disease the perception of angina tends to deteriorate with advancing age. The mechanism is unclear but is not attributable solely to alterations in blood pressure or autonomic function.

The perception of angina in diabetes: relation to somatic pain threshold and autonomic function

Silent ischemia is common in diabetic patients with coronary heart disease. These patients may also have more subtle alteration in the perception of angina as reflected by prolongation of anginal perceptual threshold--the time from onset of 0.1 mV ST segment depression to the onset of chest pain during treadmill exercise. Silent ischemia may be associated with a generalized hyposensitivity to pain, although the pathophysiologic mechanism is obscure. The purpose of the present study was to determine whether diabetic patients with prolonged anginal perceptual thresholds are also hyposensitive to painful stimuli and to investigate whether this is associated with autonomic neuropathy. Nineteen diabetic and 25 nondiabetic patients with exertional angina were exercised on a treadmill to measure anginal perceptual threshold. Somatic pain threshold was measured by calf sphygmomanometry. The cuff was inflated rapidly until pain occurred, and six repeat inflations were done to test reproducibility. Because there was no significant difference between measurements (coefficient of variation = 0.156) the mean value for each patient provided a measure of somatic pain threshold. The diabetic group had a longer anginal perceptual threshold (138 +/- 64 seconds vs 34 +/- 51 seconds, p less than 0.001), which correlated positively with the somatic pain threshold (r = 0.5, p = 0.03); patients with more prolonged anginal perceptual thresholds tended to have higher somatic pain thresholds. In the diabetic group anginal perceptual (r = -0.3, p = NS) and somatic pain (r = -0.4, p = 0.05) thresholds tended to increase as the ratio of peak to minimal heart rate during the Valsalva maneuver fell below 1.21, but these variables were unrelated in the nondiabetic group.(ABSTRACT TRUNCATED AT 250 WORDS)

Insensitivity of noninvasive tests to detect coronary artery vasculopathy after heart transplant

Obstructive coronary artery vasculopathy can be a major problem after cardiac transplant. The use of noninvasive tests to detect coronary artery vasculopathy was studied in 73 consecutive patients after heart transplant. Angiographically or autopsy-proved coronary artery disease was noted in 19 consecutive patients (26%) followed prospectively for 2.5 +/- 1.3 years (mean +/- standard deviation). Patients underwent yearly surveillance echocardiographic, rest/exercise-gated wall motion, oral dipyridamole thallium, ambulatory electrocardiographic monitor and angiographic studies. Positive test results were defined by decrease in ejection fraction, wall motion abnormality, failure to increase ejection fraction, lack of systolic blood pressure increase, and ischemic ST changes at maximal exercise (or on ambulatory monitor). Wall motion abnormalities and depressed ejection fraction on echocardiography were also abnormal studies as were fixed or reversible perfusion defects on thallium scan. Angiograms were considered positive when 50% luminal narrowing was observed and autopsy coronary artery vasculopathy was defined as cross-sectional coronary obstruction greater than or equal to 70%. No procedure that was examined proved to be a sensitive noninvasive detector of heart transplant coronary artery vasculopathy. All except ambulatory electrocardiographic monitoring had positive predictive values less than 50%. Interestingly, of the techniques evaluated, echocardiography was most sensitive (53%). The poor predictive ability of noninvasive testing in this population may be due to the fact that these tests are designed to detect effects of ischemia rather than coronary obstruction alone. Use of these particular noninvasive modalities routinely after heart transplant to detect coronary artery vasculopathy should be reconsidered because of their low sensitivity and predictive value when used as a surveillance screen.

Self-perception of the ability to work in the cold

Accumulating evidence of beneficial effects from physical exertion must be balanced against increased risk of cardiac arrest during performance. There is evidence that, by using such cues as heart rate, individuals can monitor their level of exertion perceptually. We undertook experiments to discover whether temperature and heart rate interact to affect self-perception when the effective temperature is moved downard from the comfort zone. In the first pilot study, 36 males practiced a new game, SwedeBall, for a period of 20 minutes. Twelve were randomly assigned to play at a temperature of 22 degrees C, another 12 to play at 0 degrees C, and the remaining 12 to play at -7 degrees C. The players showed tendencies toward an overall improvement in self-evaluations after brief practice, with more favorable responses when the temperatures were lower. In a second experiment on different days, 8 men pedaled a standard bicycle mounted as a wind trainer in a controlled environment chamber where the effective temperature was set at 26 degrees C, 8 degrees C, or -10 degrees C. The first 5-minute ride at each temperature was at a heart rate of 120 beats per minute (bpm), the second at 140 bpm, and a third at 160 bpm. We measured ratings of perceived effort (RPE), thermal impression, discomfort, perceived rate of speed, and projected endurance. The result confirmed that RPE was lowered by temperature when heart rate was constant. The data also showed that the lowered temperatures uniformly produced more favorable self-perceptions on the other four scales. The outcome is related to physiological problems that might arise when temperature depresses heart rate and reduces the experience of effort.

Prolonged anginal perceptual threshold in diabetes: effects on exercise capacity and myocardial ischemia

Anginal perceptual threshold (the time from onset of 0.1 mV of ST segment depression to onset of angina during treadmill exercise) is prolonged in diabetic patients with coronary artery disease. In the present study, the functional significance of this perceptual abnormality was evaluated by analysis of its effect on exercise capacity and the severity of myocardial ischemia. Treadmill exercise in 32 diabetic patients and 36 nondiabetic control patients showed a close linear correlation between the time to onset of electrical ischemia (ST segment depression) and exercise capacity in both groups (r = 0.8 and 0.9, respectively; p less than 0.001). However, the slope of the relation was flatter in the diabetic group because prolongation of the anginal perceptual threshold permitted continued exercise as ischemia intensified. The anginal perceptual threshold itself showed a close linear correlation with exercise capacity in the diabetic group (r = 0.8, p less than 0.001), although in the nondiabetic group these variables were unrelated. The permissive effect of a prolonged anginal perceptual threshold on exercise capacity is undesirable as reflected by its correlation with ischemia at peak exercise (r = 0.6, p less than 0.001): the longer the threshold, the greater the exercise capacity and the more severe the ischemia. Indeed, the inverse relation between the severity of ischemia at peak exercise and exercise capacity in the nondiabetic group (r = 0.4, p less than 0.02) was completely lost in the diabetic group. Thus, in diabetic patients with coronary artery disease, anginal perceptual threshold is a major determinant of exercise capacity.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevalence, incidence and prognosis of recognized and unrecognized myocardial infarction in persons aged 75 years or older: The Bronx Aging Study

The prevalence, incidence and prognosis of recognized and unrecognized Q-wave myocardial infarction (MI) was assessed in an 8-year prospective study of 390 community-based subjects (age 75 to 85 years at entry, mean 79 years). Subjects were studied at baseline and with annual follow-up electrocardiographic (ECG) exams. At baseline, 7.9% had a history of MI without ECG evidence, 6.4% had ECG evidence of Q-wave MI without clinical history, 4.1% had both clinical history and ECG evidence and 81.5% had neither history nor ECG evidence (control subjects). After an average follow-up period of 76.2 months, the total mortality rate was 5.9/100 person-years for subjects with some evidence of MI at baseline versus 3.9 in the control group (p = 0.059). The incidence of cardiovascular disease in subjects with evidence of MI was 8.8/100 person-years versus 4.7 among control subjects (p = 0.002). During the follow-up period, 115 new Q-wave MIs occurred (50 unrecognized, rate 2.4/100; 65 recognized, rate 3.2/100). There was no difference in mortality and morbidity outcome between subjects with recognized and unrecognized MIs. Those with only a history of MI at baseline had a threefold greater risk of a new MI (recognized and unrecognized) than the control group (p = 0.003). Unrecognized Q-wave MI is a common occurrence in the "old old" with subsequent morbidity and mortality prognosis comparable to that of recognized MI. History of MI alone in this age group is also associated with an increased risk of MI, suggesting the need for better diagnostic markers of myocardial ischemia in the old.

A new semiautomated algorithm to quantify Holter-detected myocardial ischemia: preliminary experience in the Trimetazidine European Multicenter trial (TEMS)

Holter-detected myocardial ischemia, either painful or painless, is an important issue in the functional and prognostic evaluation of coronary patients. This paper describes one of the first attempts to reliably quantify the duration and severity of the ischemic ST-segment changes over a given period of time; the algorithm described here provides physicians with a global index of ischemia that is the total ischemic area, namely, the integral of ST-segment depression or elevation over time (expressed in mm x min). The diagnostic and prognostic power of this new index remains to be established and to be compared with the actually used simple measurements, i.e., the number and duration of ischemic events.

Silent versus symptomatic myocardial ischemia during exercise testing: a comparison with coronary angiographic findings

Two-hundred-and-eighty individuals with anginal complaints, without prior myocardial infarction and with a positive exercise stress test were divided into a group (n = 67) with exercise-induced silent myocardial ischemia and another group (n = 213) with exercise-induced angina pectoris. Both underwent coronary angiography and were compared with each other with respect to various exercise and angiographic parameters. Patients with exercise-induced silent ischemia attained a longer mean exercise duration (P less than 0.001), a higher peak exercise heart rate (P less than 0.0001) and a higher peak exercise rate pressure product (P less than 0.001) than patients with exercise-induced angina pectoris. In the latter group, more patients showed exercise-induced ST-segment depression greater than 2 mm (P less than 0.05). The group of patients with silent ischemia encompassed more individuals with normal coronary arteries (P less than 0.0001). More patients with exercise-induced angina pectoris had three-vessel disease (P less than 0.0001). The exclusion of patients with normal coronary arteries (23% in those with silent ischemia group and 6% in those with exercise-induced angina had no influence on the level of significance for peak heart rate, mean exercise duration and exercise duration greater than 10 min. Thus, in this population, exercise-induced silent myocardial ischemia is associated with better exercise performance and less extensive coronary arterial pathology than in exercise-induced angina pectoris.

Nitrates: why and how should they be used today? Current status of the clinical usefulness of nitroglycerin, isosorbide dinitrate and isosorbide-5-mononitrate

Nitrates are highly effective both in terminating acute attacks of angina pectoris and in the prophylaxis of symptomatic and asymptomatic myocardial ischemia. Preload reduction by venodilatation is the prevailing mechanism of nitrates in patients with chronic stable angina and is the unique feature distinguishing them from beta and calcium-channel blockers. Nitrates dilate coronary arteries not only in pre- and poststenotic vessels, but also in eccentric lesions. In patients with endothelial dysfunction, nitrates seem to be the physiological substitute for endothelium-derived relaxing factor. During the past decade, however, there has been substantial evidence of a clinically relevant loss of the anti-ischemic effects ("nitrate tolerance"). Many studies with oral dosing of isosorbide dinitrate or isosorbide-5-mononitrate at least three times daily have proven nitrate tolerance in patients with coronary artery disease and/or congestive heart failure. Complete loss of anti-ischemic effects after repetitive, continuous patch attachments has also been found. As we first showed in 1983, intermittent therapy with once-daily ingestion of high-dose sustained-release isosorbide dinitrate was successful in preventing the development of tolerance. Similarly, tolerance to isosorbide-5-mononitrate also does not develop when it is ingested once daily. It is now generally accepted that a daily low-nitrate interval is required to prevent tolerance development. Although the minimal patch-free interval required to prevent tolerance needs further investigation, a 12-h patch-free interval should prevent tolerance in most patients. The prolonged duration of action of once-daily high-dosage administration of sustained-release formulations, the improved patient compliance with a single daily administration, and the increased likelihood of maximal anti-ischemic effects are important reasons for recommending high single daily doses of isosorbide dinitrate or isosorbide-5-mononitrate.

Clinical correlates and prognostic significance of type A behavior and silent myocardial ischemia on the treadmill

Type A patients with coronary artery disease (CAD) tend to ignore or underreport symptoms, especially during challenging tasks such as the treadmill exercise test. To determine whether type A CAD patients might be more likely than type B patients to have silent ischemia during exercise and consequently a worse prognosis, 403 patients with stable CAD who had significant coronary disease on angiography, a positive Bruce protocol treadmill test and a structured interview to assess type A behavior were studied. Median follow-up time was 6 years. Type A patients were more likely to experience silent ischemia during exercise than were type B patients (35 vs 25%, p = 0.05). Patients with silent ischemia during exercise had a history of fewer anginal episodes/week, and type A patients with silent ischemia were less likely to have had a history of typical angina. However, using the Cox model, there were no significant differences in survival between type A patients and B patients with silent ischemia (4-year survival 86 vs 79%, p = 0.44) and no significant differences in survival between type A patients with silent ischemia and type A patients with symptomatic ischemia (6-year survival 86 vs 80%, p = 0.59). Similar results were obtained for infarction-free survival. Type A patients are more likely than type B patients to have silent ischemia during exercise, but long-term survival is not affected.

Cardiovascular reactivity and silent ischemia in response to mental stress in symptomatic and asymptomatic coronary artery disease patients: results of a pilot study

The current study was designed to examine cardiovascular reactivity to psychological tasks and its relationship to provocation of ischemia in asymptomatic coronary artery disease (CAD) patients with documented silent ischemia and those with painful ischemia. ECG, heart rate, and blood pressure responses to mental stress were collected for 13 patients with coronary artery disease (CAD) and for 6 healthy control subjects. Six of the CAD patients were asymptomatic (documented silent ischemia and no history of angina), while the remaining 7 were symptomatic (history of angina). Three types of mental stress were employed: white noise (a passive stressor), digits repeated backwards (an active stressor), and a math task plus white noise (active + passive stressor). Results indicate that significant increases in heart rate and blood pressure, but not silent ischemic episodes, were induced by the mental stress tasks. In addition, patients with documented exercise-induced and ambulant silent ischemia showed trends of blunted autonomic responsiveness to the stressors. On the digits backwards task, the CAD patients with silent ischemia showed significantly lower diastolic blood pressure responses compared with controls or angina patients. Findings suggest that ischemic episodes are not easily induced by brief mental stress. However, results indicate that asymptomatic CAD patients with silent ischemia may be lacking in autonomic responsiveness, particularly in terms of peripheral resistance, to mental stress in comparison with health controls and symptomatic ischemic patients. Further investigation is needed to explore how patients with silent ischemia typically respond autonomically to mental stress and how blunted reactivity may relate to the provocation of unrecognized ischemic episodes.

The role of exercise-induced silent myocardial ischemia in patients with abnormal left ventricular function. A report from the Coronary Artery Surgery Study (CASS) registry

To evaluate the significance of ischemic ST depression without anginal chest pain (silent ischemia) during exercise testing among patients with abnormal left ventricular function, the data on 121 such patients with proven coronary artery disease (CAD) from the Coronary Artery Surgery Study (CASS) registry were analyzed. The patients with silent ischemia (group 1) were compared to: 124 CAD patients with both ST depression and angina (symptomatic ischemia, group 2); 159 CAD patients with neither ST depression nor angina (no ischemia, group 3); and 37 patients without CAD (controls). Survival at 7 years with medical therapy was similar for groups 1 (55%) and 2 (60%), but was substantially better for group 3 (73%, p = 0.001). Among group 1 patients with silent ischemia, survival was related to the severity of CAD (p = 0.001). Patients with silent ischemia and three-vessel CAD had a poor 7-year survival rate (37%) when treated medically. A comparable but non-randomized group of patients with silent ischemia and three-vessel CAD who underwent coronary artery bypass surgery had a much better 7-year survival rate (83%, p less than 0.0001). These results suggest that among patients with CAD and abnormal left ventricular function, silent ischemia adversely affects survival and can identify a higher risk subset of patients whose survival might be improved after coronary bypass surgery.

The utility of the presence or absence of chest pain in patients with suspected acute myocardial infarction

In 422 patients admitted from the emergency department (ED) for suspected acute myocardial infarction, the hypothesis that chest pain that persists on arrival in the ED or recurs during the initial ED evaluation is a useful predictor of acute myocardial infarction (AMI) and complications of coronary ischemia was tested. Compared with patients whose chest pain spontaneously ceased before arrival in the ED, patients whose chest pain persisted or recurred during the initial ED evaluation had a 2.3 times greater risk of interventions (P less than .001), a 1.7 times greater risk of complications (P = .045), a 3.8 times greater risk of life-threatening complications (P = .04), and a 2.4 times greater risk of AMI (P = .005). A third group of patients with suspected AMI never experienced chest pain. This group of patients who never experienced chest pain had a three times higher risk of death (P = .02) compared with patients whose chest pain persisted or recurred in the ED, and a 2.1 times greater risk of intervention (P = .01), a 5.2 times greater risk of life-threatening complication (P = .015), and a 7.9 times greater risk of death (P = .025) compared with patients whose chest pain resolved before arrival in the ED. It was concluded that patients with chest pain that resolves spontaneously before arrival to the ED have a better in-hospital prognosis than any other group.

Asymptomatic left main coronary artery disease in the Coronary Artery Surgery Study (CASS) registry

Left main coronary artery disease (i.e., greater than or equal to 50% stenosis) was found in 1,477 of 20,137 patients in the Coronary Artery Surgery Study (CAS) registry. Of these patients, 53 (3.6%) were asymptomatic. Asymptomatic and symptomatic patients were similar in regard to 1) severity of left main coronary artery stenosis (67% vs. 70%), 2) extent of proximal coronary artery disease (no differences in number of or severity of proximal stenoses), 3) left ventricular end-diastolic pressure (13 mm Hg vs. 14 mm Hg), 4) left ventricular wall motion score 9.1 vs. 8.7), and 5) number of coronary artery segments with greater than 70% stenosis (4.4 vs. 4.8). Among the asymptomatic patients, 47% received medical and 49% received surgical treatment. In the symptomatic group, 20% received medical and 78% received surgical therapy. The survival rate 5 years after surgery for treatment of left main coronary artery stenosis was 84% for the symptomatic patients and 88% for the asymptomatic patients (p = NS). Medical management of left main coronary artery disease produced a 5-year survival rate of 57% for asymptomatic patients and 58% for symptomatic patients. Within the asymptomatic subgroup, 88% of those surgically treated survived 5 years, whereas only 57% of those medically treated survived 5 years (p = 0.02). Thus, for CASS patients with left main coronary artery disease, the percentage of those that were asymptomatic is low (3.6%); asymptomatic and symptomatic patients with left main coronary artery disease had no significant difference in severity of left main coronary artery stenosis, extent of overall coronary artery disease, or left ventricular function.(ABSTRACT TRUNCATED AT 250 WORDS)

Silent myocardial ischaemia in patients referred for coronary bypass surgery because of angina: a comparison with patients whose symptoms were well controlled on medical treatment

The frequency and characteristics of silent ischaemia were prospectively studied in 114 patients with confirmed coronary artery disease and angina. Fifty seven patients who had angina that was not adequately controlled by standard medications were referred for elective coronary artery bypass surgery (group 1). Fifty seven other patients had symptoms that were well controlled on medical treatment (group 2). Patients underwent treadmill exercise testing (n = 109) and 48 hours of ambulatory ST segment monitoring (total 5125 hours). Patients in group 1 had more severe coronary artery disease and a shorter time to 1 mm ST segment depression and maximal exercise. Twenty two patients in group 1 (38%) and 16 in group 2 (28%) had greater than or equal to 1 episode of silent ischaemia during 48 hours of ST monitoring. There was no significant difference in the mean frequency of silent ischaemic episodes in 24 hours between the two groups (group 1 0.72 v group 2 0.64); however, the mean frequency of painful ischaemic episodes in 24 hours was greater in group 1 patients (0.51) than in group 2 (0.11). In both groups the frequency of silent ischaemia was significantly related to a positive exercise test, as was the total duration of silent ischaemia. The circadian variation of silent ischaemia showed a peak of episodes in the evening in both groups. The frequency of silent ischaemia in patients with coronary artery disease and angina receiving standard antianginal medications was not related to the severity of symptoms, but was significantly related to a positive exercise test. Thirty three percent of the patients studied had evidence of silent ischaemia during 48 hours of ambulatory ST segment monitoring; however, only four patients (3.5%) had frequent (>/=5) daily episodes of silent ischaemia.

Estimation of jeopardized left ventricular myocardium in symptomatic and silent ischemia as determined by iodine-123 phenylpentadecanoic acid rotational tomography

Whether patients with silent myocardial ischemia have a lesser mass of ischemic myocardium than patients with symptomatic ischemia is controversial. Forty-five patients with angiographic coronary artery disease (greater than or equal to 70% luminal diameter narrowing) were studied. All patients had ischemic patterns of myocardial uptake and clearance of the long-chain fatty acid perfusion/metabolic imaging agent iodine-123 phenylpentadecanoic acid after maximal exercise. Single-photon emission computed tomography was performed and 25 myocardial segments were analyzed using circumferential activity profile curves. The 21 patients with silent treadmill ischemia exercised longer than the 24 patients with painful treadmill ischemia (430 +/- 137 vs 337 +/- 96 seconds, p less than 0.01) and to a higher heart rate (138 +/- 21 vs 125 +/- 18 beats/min, p less than 0.05). Patients with treadmill silent ischemia had the same number of abnormally perfused myocardial segments as patients with painful treadmill ischemia (8.6 +/- 4.5 vs 6.5 +/- 4.1 segments, difference not significant) and the same number of reversibly ischemic myocardial segments (4.0 +/- 1.4 vs 4.2 +/- 3.0 segments, difference not significant). The angiographic severity and extent of coronary artery disease were similar in the 2 groups. Thus, in this selected group of patients, those with silent treadmill ischemia appear to have at least as great an extent of ischemic myocardium as patients with painful exertional ischemia.

Asymptomatic left main coronary artery disease and silent myocardial ischemia

Gathering data on the prognosis, detection, and natural history of asymptomatic left main coronary artery disease with silent myocardial ischemia is difficult. Epidemiologic studies of unexpected death and postmortem studies on silent myocardial infarction suggest this entity to be common. We reviewed 89 consecutive patients with left main coronary artery disease (LMD), defined as 50% or greater reduction of luminal diameter. Of this group, 10 patients (11%) were asymptomatic (ALMD) and 79 patients (88%) were symptomatic (SLMD). All 10 ALMD patients were men, with a mean age of 53 years (range 40 to 65). Treadmill tests (TMT) were performed for: ECG abnormalities six; pre-jogging evaluation two; risk factor evaluation two. The TMT within 9 minutes showed 2 mm or greater ST depression in seven (70%) and 1 to 2 mm in three (30%). Similar TMT results were obtained in the SLMD group, although two patients had negative responses. The degree of stenosis of the left main coronary artery and the frequency of three-vessel disease were similar in both groups. The ejection fraction (EF) and contractile pattern of the left ventricle (LV) were normal in all 10 ALMD patients, but the left ventricular end-diastolic pressure (LVEDP) was abnormal in three (70%). In the SLMD group, 51 (64%) had an abnormal ejection fraction, 50 (65%) had wall motion abnormalities, and 25 (32%) had an abnormal LVEDP.

Painless versus painful myocardial ischemia: different left ventricular dysfunction detected by echocardiography

The mechanism responsible for the absence of anginal pain in patients who have episodes of both painless and painful myocardial ischemia, still remains unknown. Does the pain depend on an overstimulation of receptive structures or is this symptom the product of the excitation of a well-defined receptive system? The aim of this work is to test the first hypothesis: whether silent attacks are accompanied by the same degree of mechanical impairment as symptomatic ones. The authors compared the echocardiographic left ventricular functional behavior in the same patient (6 patients) during painful and painless myocardial ischemia. The echocardiographic changes observed during silent ischemic attacks were significantly different from those detected during symptomatic attacks. The latter were characterized by a larger extension of the ischemic myocardium and, as a consequence, by a larger functional impairment. Symptomatic and asymptomatic ischemic attacks were recorded echocardiographically in the same patient during repeated attacks on the same day, and were always clearly differentiated by the degree of wall motion abnormalities. The echocardiographic monitoring during the ischemic attack seemed to confirm that the greater functional impairment preceded the onset of pain leading to the occurrence of this symptom. Nevertheless, it was impossible to identify a threshold value above which the ischemic attack will be symptomatic. Our data seem to indicate a close relationship between painful ischemia and a higher degree of ischemic damage. Thus, in patients with predominantly painful myocardial ischemia, the extension and the severity of ischemia could play an important role in determining this symptom.

Do low levels of labour pain reflect low sensitivity to noxious stimulation?

In a study investigating factors affecting labour pain, 10 out of 97 subjects reported that they had never experienced any pain outwit childbirth. These subjects experienced comparatively low levels of pain within childbirth. They did not differ significantly from the majority of subjects on a large number of obstetric and psychological factors which normally affect pain in labour. It was suggested that these subjects were relatively insensitive to noxious stimulation, in that they do not experience pain when noxious stimulation is mild or moderate (as for example a consequence of menstruation, common accidents or ailments) and experience lower than average levels of pain when noxious stimulation is intense as in labour. Further investigation of such subjects is of theoretical interest and practical importance since it might allow for accurate prediction of pain levels in a proportion of parturants.