Contemporary management of silent ischemia: the role of ambulatory monitoring

The multiple arrhythmia dataset evaluation database (M.A.D.A.E.)

The convergence between wearable and medical device technologies is a natural progression. Miniaturization has allowed the design of small, compact monitoring systems that can record physiological signals over longer periods of time. Thus, the potential for these devices to expand the understanding of disease progression and patients' clinical status is very high. The accuracy of these devices, however, is dependent upon the computer algorithms utilized in the analysis of the large volume of physiological data monitored and/or recorded by the devices. Automated interpretation of the data by these new technologies, therefore, necessitates closer examination by regulatory organizations. The current requirements for the validation of novel Ambulatory ECG (A-ECG) annotation algorithms are based on the AAMI/ANSI-EC57 and IEC60601-2-47 Standard. These standards are being updated, but they rely on a very limited set of digitized ECG recordings from a couple of ECG databases built in the first half of the 70's. These reference signals are obsolete. We are developing a validation tool for computerized methods designed to detect and monitor cardiac activities based on body-surface ECGs. We will rely on a set of existing digital high-resolution 12‑lead A-ECG recordings acquired in cardiac patients and healthy individuals. These ECG signals include a large and unique set of electrocardiographic events. This tool is being qualified by the Center for Devices and Radiological Health of the United States Food and Drug Administration (FDA) as a Medical Device Development Tool (MDDT). This document provides insights into the design of the M.A.D.A.E. database, its functionalities, and its ultimate role in enabling the next generations of automatic interpretation of ECG signals.

Ambulatory monitoring of myocardial ischemia in the 21st century-an opportunity for high frequency QRS analysis

Ambulatory monitoring represents an effective tool for the assessment of silent and transient myocardial ischemia during routine daily activities. Incidence of silent ischemia can provide important prognostic information about patients with coronary artery disease or acute coronary syndrome, as well as about post-myocardial infarction patients. The current technological progress enables development of powerful and miniaturized wearable devices for Holter monitoring. Higher sampling rates, dynamic range, and extended computational and storage capacity allow for considering of more complex methodological solutions such as high-frequency QRS analysis for diagnosing myocardial ischemia. Implementation of suitable methodologies for advanced detection of myocardial ischemia into modern ambulatory monitoring devices creates the potential of making the ambulatory myocardial ischemia monitoring a valuable diagnostic tool in clinical practice.

Impaired fasting glucose in combination with silent myocardial ischaemia is associated with poor prognosis in healthy individuals

AIM

As both impaired fasting glucose and silent myocardial ischaemia are risk factors for cardiovascular disease and death, we hypothesized that these risk factors in combination would identify those subjects at the highest risk of adverse events.

METHODS

Healthy individuals without diabetes (n=596, 55-75 years) were examined for silent myocardial infarction (≥ 1 mm ST-interval during ≥ 1 min) by ambulant 48-h continuous electrocardiogram monitoring and impaired fasting glucose (fasting plasma glucose 5.6-6.9 mmol/l).

RESULTS

After 6.3 years, 77 subjects met the endpoint of myocardial infarction and/or death. The prevalence of silent myocardial ischaemia at inclusion was 12.3% in subjects with impaired fasting glucose and 11.7% in subjects with normal fasting glucose, P=0.69. Subjects with impaired fasting glucose/silent myocardial ischaemia more often met the endpoint (36%) than subjects with impaired fasting glucose/no silent myocardial ischaemia (15%), subjects with normal fasting glucose/silent myocardial ischaemia (12%), and subjects with normal fasting glucose/no silent myocardial ischaemia (10%), respectively, (P<0.001). In a Cox model including these four study groups of interest, gender, age, smoking habits, blood pressure and total cholesterol, only subjects with impaired fasting glucose/silent myocardial ischaemia exhibited an increased risk of death or myocardial infarction (hazard ratio 2.5, P=0.016).

CONCLUSION

The combination of impaired fasting glucose and silent myocardial ischaemia was associated with the poorest prognosis in middle-aged and older subjects without previously known glucose metabolic aberration and heart disease.

Cardiovascular risk evaluation and prevalence of silent myocardial ischemia in subjects with asymptomatic carotid artery disease

Introduction:

Silent ischemia is an asymptomatic form of myocardial ischemia, not associated with angina or anginal equivalent symptoms, which can be demonstrated by changes in ECG, left ventricular function, myocardial perfusion, and metabolism. The aim of this study was to evaluate the prevalence of silent myocardial ischemia in a group of patients with asymptomatic carotid stenosis.

Methods:

A total of 37 patients with asymptomatic carotid plaques, without chest pain or dyspnea, was investigated. These patients were studied for age, sex, hypertension, diabetes, dyslipidemia, smoking, and family history of cardiac disease, and underwent technetium-99 m sestamibi myocardial stress-rest scintigraphy and echo-color Doppler examination of carotid arteries.

Results:

A statistically significant relationship (P = 0.023) was shown between positive responders and negative responders to scintigraphy test when both were tested for degree of stenosis. This relationship is surprising in view of the small number of patients in our sample. Individuals who had a positive scintigraphy test had a mean stenosis degree of 35% ± 7% compared with a mean of 44% ± 13% for those with a negative test. Specificity of our detection was 81%, with positive and negative predictive values of 60% and 63%, respectively.

Conclusion:

The present study confirms that carotid atherosclerosis is associated with coronary atherosclerosis and highlights the importance of screening for ischemic heart disease in patients with asymptomatic carotid plaques, considering eventually plaque morphology (symmetry, composition, eccentricity or concentricity of the plaque, etc) for patient stratification.

Silent ischemia: silent after all?

OBJECTIVE

To examine the association of nonpain symptoms in men and women with exercise-related silent ischemia, as well as the independence of these findings from other clinical factors.

METHODS

A prospective study of 482 women and 425 men (mean age 58 years) undergoing exercise stress testing with myocardial perfusion imaging. Analyses were performed on 60 women and 155 men with no angina but medical perfusion imaging evidence of ischemia during exercise.

MEASURES

The presence of various non-pain-related symptoms. Ischemia is indicated by myocardial perfusion defects on exercise stress testing with single photon emission computed tomography.

RESULTS

Women reported more nonangina symptoms than men (P<0.05). They experienced fatigue, hot flushes, tense muscles, shortness of breath and headaches more frequently (P<0.05). Symptoms relating to muscle tension and diaphoresis were associated with ischemia after controlling for pertinent clinical covariates. However, the direction of association differed according to sex and history of coronary artery disease events or procedures. Sensitivity of the detection models showed modest improvements with the addition of these symptoms.

CONCLUSIONS

While patients who experience silent ischemia experience a number of nonpain symptoms, those symptoms may not be sufficiently specific to ischemia, nor sensitive in detecting ischemia, to be of particular help to physicians in the absence of other clinical information.

Diagnostic and prognostic value of ambulatory ECG (Holter) monitoring in patients with coronary heart disease: a review

Silent ischemia, the most common expression of atherosclerotic heart disease, affects approximately 30-50% of patients during their activities of daily living. The present review provides a comprehensive and practical summary of current knowledge on perioperative myocardial ischemia through MEDLINE searches up to June 2005, using keywords including "silent ischemia," "transient ischemia," and "Holter monitoring." Holter monitoring (i.e., continuous ambulatory ST-segment monitoring) is an effective tool for assessing the frequency and duration of silent transient myocardial ischemia, particularly in patients who are post-acute myocardial infarction (MI), those with acute coronary syndromes (ACS), and in patients in the acute post-operative period. Holter monitoring allows for further risk stratification of patients who have a positive exercise ECG by collecting long-term ECG data on ischemic and arrhythmic events while patients perform routine activities. Both the presence and increased duration of transient ischemia as detected by continuous ST-segment Holter monitoring are associated with increased rates of coronary events and mortality. Holter monitoring may aid in the identification of patients and subgroups of patients with ACS who may derive the greatest benefit from antiplatelet and antithrombotic therapy. Indeed, many ongoing and upcoming trials of pharmacotherapy include ischemia on Holter monitoring as an endpoint.

Tolerability to 1-year treatment with once-daily molsidomine in patients with stable angina

Prolonged-release molsidomine 16 mg once daily) QD (has proved effective in the short-term treatment of patients with stable angina. The purpose of this multicenter study was to assess its long-term tolerability and clinical effectiveness. A total of 320 patients with stable angina were treated for 1 year with molsidomine 16 mg QD administered open label as monotherapy or add-on therapy, when beta blockers and/or calcium antagonists were prescribed concomitantly) in 128 patients, ie, 40% of cases), depending on the severity of disease and/or local therapeutic policies. In all, 293 patients (91.6%) completed the study. The proportion of patients who reported drug-related adverse events (AEs) was 9.1%, which is not significantly different (P=.13) from the 5.9% observed during previous short-term (2-4 wk) treatment. Headache accounted for 80.6% of all drug-related AEs and required discontinuation of the drug in one quarter of patients who reported the symptom (ie, 1.9% of the 320 patients involved in the study). No serious drug-related AEs occurred during the study. Tolerability to molsidomine, evaluated with use of a visual analog scale (VAS), improved by 20% from beginning to end of 1-year follow-up. Two-by-two Bonferroni's comparisons were significant at the .05 level between the 2-month assessment and assessments performed at 8, 10, and 12 months. No age-time interaction was noted (P=.82). Heart rate, blood pressure, electrocardiogram, and blood parameters showed no statistically significant or clinically relevant changes during the study. Compliance with treatment was satisfactory throughout the follow-up period. There was no significant change in the weekly frequency of anginal attacks and consumption of short-acting nitroderivatives during the 1-year study (P=.07 and P=.12,respectively), but their frequency was significantly (ie, approximately 50%) lower than during a preceding short-term treatment period (P<.0001 and P=.014, respectively). Subjective clinical status, evaluated through an appropriate VAS, improved by 38% from start to end of 1-year follow-up. Bonferroni's comparisons between baseline and subsequent 2-month evaluations were all significant at the .05 level. No age-time interaction could be seen for frequency of anginal attacks and consumption of short-acting nitroderivatives, nor for clinical status )P=.10, P=.11, and P=.51, respectively). Neither tolerability to molsidomine nor effectiveness of the drug was biased by concomitant antianginal therapies, insofar as none of these parameters showed a significant treatment type (ie, molsidomine administered as monotherapy or add-on therapy)-time interaction (VAS for tolerability: P=.44; angina: P=.39; nitroderivatives: P=.72; VAS for clinical status: P=.62). Molsidomine 16 mg QD administered for 1 y to patients with stable angina was well tolerated and remained effective during the entire treatment period, independent of age and concomitant antianginal therapy.

Erectile dysfunction and coronary atherothrombosis in diabetic patients: pathophysiology, clinical features and treatment

The current review reports recent data available in the literature on the prevalence of erectile dysfunction and the association of erectile dysfunction with overt and silent coronary artery disease in patients with diabetes mellitus. The mechanisms by which erectile dysfunction is associated with coronary artery disease and potential clinical implications of this association have been extensively analysed. In particular, the role of endothelial dysfunction in the pathophysiology of erectile dysfunction and the potential clinical usefulness of erectile dysfunction to identify diabetic patients with silent coronary artery disease have been outlined. Finally, recent guidelines on the treatment of erectile dysfunction with phosphodiesterase-5 inhibitors in diabetic patients with and without coronary artery disease have been reported and discussed.

Efficacy and safety of once- and twice-daily formulations of molsidomine in patients with stable angina pectoris: double-blind and open-label studies

Molsidomine, a sydnonimine acting as a heterocyclic direct nitric oxide donor, has been used for many years in several European countries for the treatment of patients with stable angina pectoris. The efficacy and tolerability of a novel once-daily 16-mg formulation of molsidomine (M16) were compared with those of the currently used twice-daily 8-mg molsidomine tablet (M8) in 666 patients. Study 1, a multicenter, randomized, double-blind, placebo-controlled, twin crossover study, involved 533 patients given acute and 2-week treatment with each drug formulation. Study 2, a multicenter, open-label, sequential, add-on trial, compared M16 and M8 in 133 patients. Drug effects on exercise capacity (study 1 only), frequency of anginal attacks and consumption of short-acting itroderivatives, and incidence of adverse events (AEs) were evaluated. Compared with placebo, M16 increased exercise capacity by 15% (P<.001) at the start of study 1 and by 13% (P<.001) after 2 weeks' treatment, and was not inferior to M8. In terms of anginal attack frequency and nitroderivative consumption, M16 was not inferior to M8 in either study. Moreover, compared with M8, M16 produced a statistically and clinically significant reduction in the incidence of anginal attacks in elderly (>/=75 y) but not in younger patients (<75 y) (study 2), nor in patients from study 1. No significant difference from M8 was found in either study in short-acting nitroderivative consumption. No tolerance to M8 or M16 was observed after 2-week treatment. No statistically significant differences in incidences of all AEs and drug-related AEs were observed between M16 and M8 in either study. The same held true for proportions of patients experiencing AEs and drug-related AEs on M16 vs M8: in study 1-14.3% and 11.8% for all AEs (P=.218), 6.9% and 5.4% for drug-related AEs (P=.280); in study 2-1.3% and 1.3% for all AEs, 0% and 1.3% for drug-related AEs (P>.10) in young patients; and in the elderly, 3.6% and 0% for drug-related AEs (P>.10). Only the proportion of elderly patients with all AEs was significantly higher with M16 than with M8: 14.5% vs 1.8% (P=.039). M16 once daily was effective and well tolerated in investigated patients with stable angina pectoris, particularly the elderly, affording 24 hours of therapeutic activity. M16 was not inferior to M8 given twice daily in terms of efficacy, safety profile, and tolerability.