Old unsolved problems: when and how to treat silent ischaemia

Silent myocardial ischaemia (SMI) is defined as objective evidence of ischaemia without angina (or equivalent symptoms) in the presence of coronary artery disease, differing from silent coronary artery disease. Silent myocardial ischaemia represents the majority of episodes of myocardial ischaemia at Holter monitoring. During transient myocardial ischaemia, the symptoms appear after the contraction anomalies of the left ventricle and after the ECG changes. The cause of silent myocardial ischaemia is still not well established. The severity and duration of ischaemia have been theorized as important elements in the SMI mechanism. Another possible mechanism responsible for SMI is represented by changes in the perception of painful stimuli with an increased pain threshold. Finally, a neuronal dysfunction of the diabetic, in post-infarction or a cardiac neuronal ‘stunning’ could play a role in SMI. In the pre-stent era, the SMI was associated with a worse prognosis. In patients with diabetes mellitus, SMI seems to be more represented because autonomic dysfunction is present in this category of patients. In conclusion, SMI is more frequent than symptomatic ischaemia. However, despite the presence of countless studies on the subject, it is not clear today whether medical therapy has equalized the risk and what the real prognosis of SMI is.

Coronary artery spasm due to intravenous atropine infusion in a child: possible Kounis syndrome

Coronary vasospasm can result from silent myocardial ischaemia to sudden death. There are many precipitant factors including different pharmacological agents. Kounis syndrome is defined by acute coronary syndromes associated with anaphylactic or anaphylactoid reactions. We report, to the best of our knowledge, the first paediatric case of Kounis syndrome due to intravenous atropine.

Silent Myocardial Ischaemia: A Review of the Literature for Prehospital Care Providers

Introduction There has been little emphasis in paramedic education about silent myocardial ischaemia, its implications, and management in the prehospital environment. There is also inadequate information about the aetiology and prehospital management of silent myocardial infarction. The objective of this study was to review the literature on silent myocardial ischaemia and determine appropriate prehospital management. Methods A review of the Medline database was conducted from 1950 to the beginning of March 2007. Inclusion criteria were, any study type reporting the epidemiology, pathophysiology, clinical concepts, and management of silent myocardial ischaemia. References of relevant articles were also reviewed. A review of prehospital clinical implications and management was also undertaken. Results The search yielded 1,332 articles; 110 articles met the inclusion criteria with another 32 articles located from review of relevant articles reference list. Silent myocardial ischaemia is not limited to patients with significant coronary artery disease or cardiovascular risk profiles, it may affect up to 10% of patients with asymptomatic coronary artery disease. Silent myocardial ischaemia is also associated with greater adverse outcomes, and has been defined as the single strongest factor attributing to cardiac death in patients with concurrent angina pectoris. All patients with coronary artery disease presenting with and without pain can be managed with GTN and aspirin, in the absence of contra-indications. Conclusion This study demonstrates that silent myocardial ischaemia is not limited to patients with significant cardiovascular risk profiles and may affect up to 10% of patients with asymptomatic coronary artery disease. There is little prehospital care providers can achieve with current clinical practice guidelines and management regimes.

Subclinical atherosclerosis and silent myocardial ischaemia in patients with type 2 diabetes: a protocol of a clinico-observational study

IntroductionAtherosclerotic cardiovascular disease is a significant modifiable complication in patients with diabetes and subclinical atherosclerosis is considered a surrogate marker of future vascular events. The clustering of cardiometabolic-risk factors in patients with diabetes and cardiovascular disease is increasingly being recognised. Recent evidence indicates that 20–50% of asymptomatic patients with diabetes may have silent coronary heart disease. However, the identification of subclinical atherosclerosis and silent myocardial ischaemia in patients with diabetes has been less well-explored, especially in low-resource population settings where cost-effective non-invasive clinical tools are available. The objective of this study is to identify patients with physician-diagnosed diabetes who are at risk of developing future cardiovascular events measured as subclinical atherosclerosis and silent myocardial ischaemia in an urban population of Eastern India.Methods and analysisThis is a cross-sectional clinico-observational study. A convenience sampling of approximately 350 consecutive patients with type 2 diabetes based on predefined inclusion and exclusion criteria will be identified at an urban diabetes center. This estimated sample size is based on an expected prevalence of silent myocardial ischaemia of 25% (± 5%), we computed the required sample size using OpenEpi online software assuming an α level of 0.05 (95% CI) to be 289. On factoring 20% non-response the estimated sample size is 350. Previously validated questionnaire tools and well-defined clinical, anthropometric and biochemical measurements will be utilised for data collection. The two primary outcomes—subclinical atherosclerosis and silent myocardial ischaemia will be measured using carotid intima-media thickness and exercise tolerance testing, respectively. Descriptive and multivariate logistic regression statistical techniques will be employed to identify ‘at risk’ patients with diabetes, and adjusted for potential confounders.Ethics and disseminationEthical approval was granted by the institutional review board of Kalinga Institute of Medical Sciences, Bhubaneshwar, India. Data will be presented at academic fora and published in peer-reviewed journals.

A silent myocardial infarction in the diabetes outpatient clinic: case report and review of the literature

Summary Silent myocardial ischaemia (SMI), defined as objective evidence of myocardial ischaemia in the absence of symptoms, has important clinical implications for the patient with coronary artery disease. We present a dramatic case of SMI in a diabetes patient who attended annual review clinic with ST elevation myocardial infarction. His troponin was normal on admission but raised to 10.7 ng/ml (normal <0.5) when repeated the next day. His angiogram showed diffused coronary artery disease. We here discuss the implications of silent ischaemia for the patient and for the physician caring for patients with diabetes. Learning points Silent myocardial ischaemia (SMI) is an important clinical entity. SMI is common and occurs with increased frequency in patients with diabetes. SMI is an independent predictor of mortality. Recognition may lead to early intervention.