Effect of aspirin on myocardial ischemia

No significant detectable anti-infection effects of aspirin and statins in chronic obstructive pulmonary disease

BACKGROUND

Past studies have shown that aspirin and statins decrease the rate and severity of exacerbation, the rate of hospitalization, and mortality in chronic obstructive pulmonary disease (COPD). Although these studies are relatively new, there is evidence that new therapeutic strategies could prevent exacerbation of COPD.

TRIAL DESIGN

This article examines retrospectively the possibility of using aspirin and statins to prevent exacerbation and infection in patients with COPD.

METHODS

All patients with COPD were identified from hospital charts in the Department of Internal Medicine, Saarland University Medical Center, Germany, between 2004 and 2014.

RESULTS

The study examined 514 medical reports and secured a study population of 300 with COPD. The mean age was 69 ± 10 years (206 men, 68.7%, 95% CI, 63.4-73.9; 94 women, 31.3%, 95% CI, 26.1-36.6). The study results did not show a causal relationship between aspirin and statins and prevention of exacerbation and infection in patients with COPD.

CONCLUSION

In contrast, in this study, the exacerbation and infection rates increased under medication with aspirin and statins (p = 0.008).

The clinical significance of continuous ECG (ambulatory ECG or Holter) monitoring of the ST-segment to evaluate ischemia: a review

Silent ischemia is a common manifestation of coronary artery disease (CAD). Continuous ECG (cECG) monitoring is an effective tool for assessing the frequency and duration of silent ischemic episodes for patients with CAD and for risk stratifying asymptomatic patients or those after an acute coronary syndrome by identifying those at increased risk for future cardiovascular events or death. cECG also allows monitoring of the effectiveness of therapy in patients with CAD. Treatment strategies targeted toward the elimination of silent ischemia have shown that revascularization was better than medical therapy in eliminating silent ischemia, but large scale, prospective studies targeting silent ischemia as a treatment endpoint are still lacking. Future research is warranted to study the effects of newer medical agents or the selected use of revascularization in those patients with persistent silent ischemia despite current medical regiments.

Silent ischemia: clinical relevance

Myocardial ischemia can occur without overt symptoms. In fact, asymptomatic (or silent) ST-segment depression during ambulatory electrocardiogram monitoring occurs more often than symptomatic ST-segment depression in patients with coronary artery disease. Initial studies documented that silent ischemia provided independent prediction of adverse outcomes in patients with known and unknown coronary artery disease. The ACIP (Asymptomatic Cardiac Ischemia Pilot Study) enrolled patients in the 1990s and found that revascularization was better than medical therapy in reducing silent ischemic episodes and possibly cardiovascular (CV) events. However, the more recent COURAGE (Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation) trial found similar CV event rates between patients treated with optimal medical therapy alone and those treated with optimal medical therapy plus percutaneous revascularization. Therefore, in the current era, medical therapy appears to be as effective as revascularization in suppressing symptomatic ischemia and preventing CV events. COURAGE was not designed to evaluate changes in the frequency of silent ischemia. Therefore, silent ischemia may persist despite current-era treatment and might still identify patients with increased risk of CV events. Also, silent ischemia is likely to occur frequently in heart transplant patients with denervated hearts and coronary allograft vasculopathy, and future study aimed at improving the management of silent ischemia in this population is warranted. Additionally, future research is warranted to study the effect of newer medical therapies such as ranolazine or selected use of revascularization (for example, guided by fractional flow reserve) in those patients with persistent silent ischemia despite optimal current-era medical therapy.

Contemporary management of silent ischemia: the role of ambulatory monitoring

Silent ischemia is highly prevalent among patients with ischemic heart disease and is associated with a poor prognosis in moderate/high risk outpatients who either exhibit exercise- or pharmacological-induced myocardial ischemia, or in those patients who demonstrate silent ischemia following an acute coronary syndrome. Pharmacotherapy, including beta-blockers, angiotensin-converting enzyme inhibitors, statins, calcium channel antagonists and antiplatelet agents, have all demonstrated a reduction in silent ischemia and an improvement in cardiac prognosis. The management of patients with ischemic heart disease is currently based on patients' report of anginal symptoms: documentation of silent ischemia, usually using ambulatory electrocardiography, is not incorporated into the routine management of coronary artery disease. Yet studies comparing ambulatory electrocardiography with exercise testing have shown these tests to be complementary. We review the evidence concerning the prognostic value of ambulatory electrocardiography for monitoring silent ischemia and the prognostic value of attenuating silent ischemia. Mitigation of silent ischemia improves cardiac prognosis and ambulatory electrocardiographic monitoring before and after treatment of silent ischemia can play a valuable role in the management of coronary artery disease.

Usefulness of ambulatory electrocardiographic monitoring for myocardial ischemia after coronary bypass

Cardiac patients with asymptomatic myocardial ischemia have a poor prognosis. Ambulatory electrocardiographic monitoring can help to ensure that these patients, who are unaware of their high-risk status, are relieved of residual myocardial ischemia in response to cardioprotective medication, and rendered as low cardiac risk.

Silent ischaemia and hypertension

For many years now, silent ischaemia has been recognized as a distinct clinical entity, and its relevance in different patient groups has been established. However, a number of basic questions have not been answered. In explaining the pathophysiology of silent ischaemia, factors affecting both the demand and the supply side are now being recognized. With the exception of certain well-defined groups, it is not clear why some patients are mostly symptomatic, while other patients are predominantly asymptomatic. There appear to be many factors influencing the ischaemic pain threshold. Studies investigating the prevalence of silent ischaemia show a remarkably high prevalence of silent ischaemia in different patient groups. Patients with hypertension but without coronary artery disease form a specific and vulnerable high-risk population that is particularly prone to silent ischaemia. Since changes at the macrovascular level are not responsible, various factors negatively influencing either cardiac supply or demand have been investigated. A reduced coronary reserve is central in explaining the increased prevalence of silent ischaemia in hypertensives. Left ventricular hypertrophy renders meaningful detection of ST segment changes difficult, but a possible solution dealing with this problem is offered by applying more stringent criteria in terms of minimal ST depression in the definition of ischaemia. The treatment of silent ischaemia is largely the same as for angina pectoris, but whether therapy should be directed at elimination of all ischaemic episodes or only of symptomatic episodes depends on further prospective work addressing this question.

Effect of aspirin on spontaneous contrast in the brachial veins of normal subjects

Blood cell aggregates are thought to be the cause of spontaneous echo contrast (SEC), although there is disagreement as to whether red cell or platelet aggregates produce this effect. One way to differentiate between these 2 possibilities is to evaluate the effect of aspirin on SEC because aspirin would not be expected to affect red cell aggregates. To eliminate the need to perform repetitive transesophageal echocardiographic studies, and the possible effect of the underlying disease process on SEC, the effect of aspirin on SEC in the brachial vein was studied in normal volunteers using a single-blind, before-and-after study design. Other factors known to affect blood echogenicity including hematocrit, sedimentation rate, and the presence of platelet aggregates by microscopy were also studied. The amount of SEC was quantitated by image analysis and expressed as the aggregate score. The results in 10 volunteers showed that all had SEC in brachial veins before aspirin, but there was no significant day-to-day variation in the amount of SEC during the control period (mean +/- SEM 104,248 +/- 23,088, 153,722 +/- 35,664, and 124,568 +/- 22,827 for days 1, 3, and 5, respectively). A significant decrease in the aggregate score occurred after 7 days of aspirin, 650 mg twice a day (51,690 vs 127,513, p = 0.002); this was accompanied by a striking decrement in the size of the largest platelet aggregate found in venous blood. Aspirin caused no significant change in the hematocrit or sedimentation rate. These results indicate that there is a component of SEC that is aspirin-sensitive and is likely to represent platelet aggregates.

Daily life cardiac ischaemia. Should it be treated?

Daily life cardiac ischaemia is defined as reversible myocardial cellular hypoxia that occurs during activities of daily living, without artificial provocation. Most of these daily life ischaemic episodes are not associated with symptoms. However, it is not practical to distinguish silent versus symptomatic daily life ischaemia as both are associated with haemodynamic abnormalities and future adverse outcomes. Daily life cardiac ischaemia is best detected using ambulatory electrocardiogram (ECG) monitoring; however, there are other diagnostic tools (e.g. exercise treadmill) that can be used. Once detected, the optimal therapy for daily life myocardial ischaemia has yet to be identified. However, it does appear that usual antianginal medications including nitrates, beta-blockers, calcium antagonists and antiplatelet drugs are effective in reducing the incidence and severity of daily life myocardial ischaemia. Medical therapy and revascularisation should be utilised to obliterate all episodes of daily life cardiac ischaemia to prevent future cardiac events. Moreover, the efficacy of the chosen therapeutic regimen for each patient should be documented with follow-up objective testing. The diagnosis and management of daily life myocardial ischaemia is continually evolving. Future research as well as economic considerations will shape future management strategies.

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.

Treatment strategies for daily life silent myocardial ischemia: A correlation with potential pathogenic mechanisms

Recent investigations of SMI occurring during daily life have advanced our understanding of the pathophysiology of myocardial ischemia. These contributions have directed our attention away from "chest pain" alone and physical exertion as the central provoking factor toward transient myocardial ischemia and its broader triggers and consequences. Transient myocardial ischemic episodes, the majority of which are silent, are found in a subset of patients with any clinical manifestations of CAD (eg, stable angina, unstable angina, myocardial infarction, and sudden death), as well as in those patients with CAD who are and have been totally asymptomatic. These episodes are an independent predictor of increased risk for future cardiac events. Most medical therapy and revascularization therapies have the potential to prevent or relieve these silent episodes; however, we do not yet know which method is superior in reducing SMI episodes or preventing future cardiac events. Furthermore, the benefit of reducing SMI versus the cost and potential morbidity of these chosen therapies is not known. At least three trials are now underway to examine some of these concerns (Table 2). Focus on pain relief alone does not appear to be an adequate approach to alter outcome in patients with CAD and may prove insufficient to control SMI. Until these issues are resolved, we believe a conservative approach to the management of patients with CAD is warranted. Documentation of ischemia (painful or painless) is essential. Three general principles should be kept in mind. First, the presence of detectable ischemia is of central importance. This information should be used in the overall risk assessment of the patient. Second, the level of concern or aggressiveness of treatment should be based on the risk associated with the ischemic abnormalities documented (Table 3). The exercise stress test is the most useful to begin this process. The detection of ischemic-type ST-segment depression, either silent or painful, at a low workload (eg, less than or equal to 120 beats per minute or less than or equal to 6.5 metabolic equivalents [METS]) implies high risk for adverse outcome. Likewise, these ST-segment changes occurring in leads that reflect multiple coronary artery distribution, of greater than 2 mm in magnitude and persisting for greater than 6 minutes, are all markers for high risk. Thallium redistribution defects occurring at low work loads, in multiple areas, associated with increased lung uptake and enlargement of the cardiac pool all imply high risk.(ABSTRACT TRUNCATED AT 400 WORDS)

Prevention of serious cardiac events by low-dose aspirin in patients with silent myocardial ischaemia. The Research Group on Instability in Coronary Artery Disease in Southeast Sweden

On exercise testing after an episode of unstable coronary artery disease (CAD; unstable angina or non-Q-wave myocardial infarction), a proportion of patients show ST-segment depression, indicating myocardial ischaemia, but do not report concomitant symptoms of angina. Treatment of such "silent" ischaemia aims mainly to reduce the risk of subsequent cardiac events. We have studied the effect of low-dose aspirin in patients with myocardial ischaemia defined at the predischarge test as silent (though patients might have had symptomatic ischaemia at other times) or symptomatic. 740 men with unstable CAD aged 70 years or less underwent symptom-limited exercise testing before hospital discharge; 144 showed ST depression without pain and 230 ST depression with simultaneous chest pain. Of the silent ischaemia group, 67 were randomly assigned placebo and 77 aspirin (75 mg daily); the corresponding numbers in the symptomatic group were 125 and 105. Angina symptoms were less common in the silent than in the symptomatic ischaemia group both before inclusion and during follow-up, and a greater proportion of the silent ischaemia group were included because of myocardial infarction. In both ischaemia groups aspirin treatment reduced the risk of subsequent myocardial infarction or death by 3 months' follow-up (silent 4% of aspirin-treated vs 21% of placebo-treated patients, p = 0.004; symptomatic 9% vs 18%, p = 0.05); at 12 months' follow-up a significant benefit of aspirin was still apparent in the silent ischaemia group (9% vs 28%, p = 0.005) but not in the symptomatic group (13% vs 22%, p = 0.109). Low-dose aspirin reduced the risk of subsequent myocardial infarction at least as well in silent as in symptomatic myocardial ischaemia. Since improvement of outlook is the main treatment objective in symptom-free patients, aspirin should be a mainstay of their treatment.

Silent myocardial ischemia after acute myocardial infarction

Silent ischemia after myocardial infarction has definite prognostic significance but should be interpreted within the context of other prognostic indicators. The rationale for therapeutic intervention is based on the prognostic implications of silent ischemia and the potentially deleterious effect of repeated episodes of ischemia on the integrity of the left ventricle. We measured parameters of ischemia in 20 patients who showed asymptomatic ischemic ST-T changes on exercise testing in the early phase after myocardial infarction. After diltiazem administration, a reduction of exercise-induced ST-T depression from 2.3 +/- 0.8 to 0.7 +/- 0.6 mm (p less than 0.01) occurred, and regional wall-motion score at exercise, determined by radionuclide angiography, improved significantly (p less than 0.02). These and other observations warrant further studies in which the duration, severity and frequency of the ischemic episodes should be quantified and correlated with prognosis after myocardial infarction.