Electrocardiography Series. ECGs of structural heart disease: Part 1

Electrocardiogram (ECG) is a useful but imperfect investigation in the diagnosis and possible follow-up of structural heart disease such as ventricular hypertrophy. Different ECG criteria with different sensitivity and specificity are available to aid the detection of left or right ventricular hypertrophy. Subsequent echocardiography can help in the quantification of ventricular mass and identification of the aetiology.

Misleading ECG recordings

Misleading electrocardiogram recordings are not uncommon, and can lead to misdiagnosis. This article highlights two examples and discusses the strategies to recognise them.

Acute myocardial infarction in young Asian women: a comparative study on Chinese, Malay and Indian ethnic groups

INTRODUCTION

There is a paucity of data on acute myocardial infarction (AMI) in young Asian women and of comparative data among various ethnic groups with respect to risk factor profile and clinical outcomes. We present a comprehensive overview of the clinical characteristics of young Asian women with AMI and a comparative analysis among Chinese, Malay and Indian women in a multi-ethnic Asian country.

METHODS

We studied 45 Asian female patients aged 50 years and below who were admitted to our hospital with a diagnosis of ST-segment elevation myocardial infarction (STEMI) or non-ST-segment elevation myocardial infarction (NSTEMI).

RESULTS

Overall, diabetes mellitus, hypertension and hyperlipidaemia were prevalent in the study population. Hyperlipidaemia was more prevalent among Indian patients, while diabetes mellitus was more common among Malay patients. Only a minority of the study patients were current smokers. Among the 20 patients admitted with STEMI, 17 (85 percent) received urgent reperfusion therapy. The mean symptom-to-balloon time and door-to-balloon time for the Malay patients were longer compared to those for other ethnic groups. Among the 25 patients admitted with NSTEMI, 12 (48 percent) underwent coronary revascularisation therapy. The average duration of hospital stay was 4 +/- 4.1 days, with no significant difference observed among the various ethnic groups.

CONCLUSION

Many young Asian women with AMI have identifiable risk factors that are different from those found in the Western population. There seems to be an ethnic effect on the prevalence of these risk factors and door-to-balloon time.

Managing ventricular ectopics: are ventricular ectopic beats just an annoyance?

How important are PVCs and what should we do about them? PVCs are not a disease in themselves, but a marker of possible underlying conditions that may increase the risk of cardiac death. They serve as a flag to alert us to exclude structural heart disease, the presence of which is the strongest predictor of adverse events. However, it is important to know that PVCs are common in people with no structural heart disease. In this situation, the prognosis is generally excellent. Suppression of PVCs with antiarrhythmic medication is not indicated routinely, unless the patient is symptomatic or at risk of tachycardia-induced cardiomyopathy owing to the very high frequency of PVCs. Where pharmacological therapy has failed, there is now the option of radiofrequency ablation for elimination of frequent symptomatic PVCs. The ECG is a simple yet useful tool to improve risk assessment, especially in those with known cardiovascular disease.

Narrow QRS complex tachycardia presenting as palpitation

Atrial fibrillation is the most common sustained cardiac arrhythmia. The rhythm in atrial fibrillation is irregular. Correct interpretation of the electrocardiogram (ECG) is essential. Atrial flutter can present as regular or irregular narrow QRS complex tachycardia. Knowledge of the ECG features of atrial flutter will help to differentiate it from paroxysmal supraventricular tachycardia. The treatment strategy in atrial fibrillation should focus on rhythm control vs. rate control, and anticoagulation should be started based on the calculated risk of systemic embolisation. Atrial flutter is a unique arrhythmia that has similar management strategies to those of atrial fibrillation; however, radiofrequency ablation is increasingly preferred due to its higher rate of efficacy and safety compared to pharmacological therapy.

Electrocardiography Series. What is the cause of the regular wide QRS complex tachycardia?

Regular broad QRS complex tachycardias may be ventricular in origin or due to supraventricular tachycardia with aberrancy. Antidromic atrioventricular re-entrant tachycardia occurring in Wolff-Parkinson-White syndrome is a third possibility. The electrocardiogram is a key tool for distinguishing these tachycardias, which have differing causes, prognoses and treatment strategies. Ventricular tachycardia may be monomorphic or polymorphic. The management of ventricular tachycardia depends on clinical symptoms and is influenced by the presence of structural heart disease.

Variations of atrioventricular block

Atrioventricular (AV) block comprises a spectrum of cardiac conduction delays with varying clinical presentations. It is commonly encountered in both hospital as well as ambulatory settings, and recognition of the type of AV conduction delay is essential for appropriate subsequent management. The electrocardiogram is a key tool for identification of patients with AV conduction delays. Contrasting management strategies should be employed for differing levels of conduction block.

Regular narrow complex tachycardia

We discuss cases of paroxysmal supraventricular tachycardia (PSVT), including the patient's presentations and clinical courses. Correct interpretation of electrocardiogram (ECG) and detailed analyses are important in differentiating the various types of PSVT. This is crucial in the immediate and long-term management of these patients.

ECG delta waves in patients with palpitation

It is important to recognise Wolff-Parkinson-White (WPW) syndrome in electrocardiograms (ECG), as it may mimic ischaemic heart disease, ventricular hypertrophy and bundle branch block. In addition, ECG can aid in the localisation of the accessory pathway. Recognising WPW syndrome allows for risk stratification, the identification of associated conditions and the institution of appropriate management.

ECG ST segment elevation in patients with chest pain

We discussed three cases of ST elevation myocardial infarction with ST elevation in the inferoposterior territory and anterior territory, and more uncommonly, concomitant ST elevations in the anterior and inferior electrocardiography (ECG) leads. Correct interpretation of the ECG is crucial in recognising this cardiac emergency, which often necessitates urgent coronary revascularisation. In addition, ECG aids localisation of the infarct-related artery and adds prognostic value.

Simultaneous thromboses of multiple coronary arteries in acute myocardial infarction

Simultaneous thrombotic occlusion of multiple coronary arteries in acute myocardial infarction is a well-recognised phenomenon. Studies have reported diffuse destabilisation of atherosclerotic plaques in patients with acute myocardial infarction, leading to the concept of "pan-coronaritis". The putative mechanism is attributed to a systemic thrombophilic and inflammatory state. We report the occurrence of this phenomenon in two middle-aged male patients.