Dr. Usman's Cardiology Notes

  Global Longitudinal Strain (GLS): When Ejection Fraction Is Normal but the Heart Is Not Introduction In modern echocardiography, Ejection Fraction (EF) has traditionally been the most commonly used parameter to assess left ventricular systolic function. However, many patients may develop subclinical myocardial dysfunction even when EF appears normal. This is where Global Longitudinal Strain (GLS) becomes extremely valuable. Strain imaging allows cardiologists to detect early myocardial damage before conventional parameters such as EF begin to decline. As a result, GLS has become an essential tool in the evaluation of patients with cardiomyopathy, chemotherapy exposure, and valvular heart disease. --- What is Global Longitudinal Strain (GLS)? Global Longitudinal Strain (GLS) is an echocardiographic parameter derived from speckle-tracking echocardiography that measures the percentage of myocardial deformation (shortening) in the longitudinal direction during systole. In simple term...

The role of inflammation in post-STEMI remodeling: findings from the PULSE-MI Trial: The Role of Inflammation in Post-STEMI Remodeling --- Introduction Despite rapid reperfusion with primary PCI, many patients with ST-segment elevation myocardial infarction (STEMI) develop adverse ventricular remodeling and heart failure. A key driver of this process is inflammation, which begins during myocardial ischemia and intensifies after reperfusion. This inflammatory cascade promotes cardiomyocyte death, microvascular injury, and fibrosis, ultimately leading to left ventricular (LV) dilation and systolic dysfunction.  The PULSE-MI trial was designed to investigate whether early suppression of inflammation using pulse-dose glucocorticoids could reduce myocardial injury and limit adverse remodeling after STEMI. --- Inflammation and Post-MI Remodeling Following coronary occlusion and reperfusion, several inflammatory pathways are activated: • Release of cytokines such as IL-1, IL-6, TNF-α • Ac...

Causes of Prolonged QT Interval The QT interval on an electrocardiogram (ECG) represents the total time for ventricular depolarization and repolarization. Prolongation of the QT interval indicates delayed ventricular repolarization and is clinically important because it increases the risk of polymorphic ventricular tachycardia, particularly Torsades de Pointes, which can lead to sudden cardiac death. What is a Prolonged QT Interval? The QT interval varies with heart rate and is usually corrected using the QTc (corrected QT interval). General reference values: QTc > 440 ms in men → prolonged QTc > 460 ms in women → prolonged QTc ≥ 500 ms → significantly increased risk of Torsades de Pointes --- Major Causes of Prolonged QT Interval 1. Congenital Long QT Syndromes These are genetic disorders caused by mutations affecting cardiac ion channels. Common types include: LQT1 – KCNQ1 mutation (potassium channel defect) LQT2 – KCNH2 mutation LQT3 – SCN5A mutation (sodium channel abnormalit...

Epsilon Wave and Sudden Cardiac Death: An Important ECG Marker of Arrhythmogenic Cardiomyopath Sudden cardiac death (SCD) in young individuals and athletes is often caused by underlying structural or electrical heart disease. One of the most characteristic electrocardiographic findings associated with malignant ventricular arrhythmias is the epsilon wave. The epsilon wave is a subtle but highly specific ECG marker of Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC), a genetic cardiomyopathy characterized by progressive fibro-fatty replacement of the right ventricular myocardium. This structural remodeling creates an arrhythmogenic substrate that predisposes patients to ventricular tachycardia, ventricular fibrillation, and sudden cardiac death. Recognition of epsilon waves on ECG can therefore be life-saving, particularly in young athletes presenting with syncope, palpitations, or unexplained ventricular arrhythmias. --- What is an Epsilon Wave? An epsilon wave is a small positiv...

Typical Sites for Radiofrequency Ablation of Common Cardiac Arrhythmias Radiofrequency catheter ablation (RFA) has become a cornerstone therapy in modern cardiac electrophysiology. By delivering controlled thermal energy to specific myocardial tissue, RFA eliminates arrhythmogenic foci or interrupts abnormal conduction pathways responsible for tachyarrhythmias. Understanding the typical anatomical targets for ablation is essential for electrophysiologists, cardiology trainees, and clinicians managing arrhythmia patients. --- 1. Atrioventricular Nodal Reentrant Tachycardia (AVNRT) Typical Ablation Site: Posterior septal region of the right atrium targeting the slow pathway. Anatomical Location Inferior part of the Triangle of Koch Near the coronary sinus ostium Between the tricuspid annulus and CS ostium Rationale AVNRT is usually caused by dual AV nodal pathways. Ablation of the slow pathway interrupts the reentrant circuit while preserving AV nodal conduction. Key Point Slow pathway m...

2026 AHA/ACC Multisociety Dyslipidemia Guidelines — Concise, High-Yield Summary 🔴 Core Concept “Lower LDL-C earlier and for longer” → reduces cumulative lifetime ASCVD risk Shift from short-term risk → lifetime risk + earlier intervention --- 🧪 1. Screening & Risk Assessment Start early Children: ~10 years (for familial hypercholesterolemia) Adults: from ≥19 years, repeat every 5 years  Use new PREVENT-ASCVD calculator Estimates 10-year + 30-year risk Treatment considered at ≥5% 10-year risk  Recognize South Asians = higher ASCVD risk  --- 🧬 2. Risk Enhancers (Expanded) Routine Lp(a) testing once in lifetime Increased emphasis on: ApoB Family history Metabolic syndrome Lp(a) → not directly treated but triggers aggressive LDL lowering  --- 🎯 3. LDL-C Targets (More Aggressive) General population: <100 mg/dL Intermediate/high risk: <70 mg/dL Established ASCVD / very high risk: <55 mg/dL  👉 Strong shift toward “treat-to-target” strategy --- 💊 4. P...

Indications for Revascularization in ST-Segment Elevation Myocardial Infarction (STEMI) ACC/AHA 2021 Guideline–Based Practical Overview --- Why Revascularization Matters ST-segment elevation myocardial infarction (STEMI) is a race against time. The underlying problem is acute coronary artery occlusion due to thrombus formation over a ruptured atherosclerotic plaque. The goal of revascularization is simple yet lifesaving: Restore coronary blood flow as quickly as possible to salvage myocardium, reduce infarct size, and improve survival. The 2021 ACC/AHA guidelines emphasize rapid, complete, and appropriate reperfusion, tailored to patient stability and system capabilities. --- Primary Principle All patients with STEMI should receive immediate reperfusion therapy unless contraindicated. Two options: Primary Percutaneous Coronary Intervention (PCI) – preferred Fibrinolytic therapy – when PCI is not timely available --- 1. Indications for Primary PCI (Class I – Strong Recommendation) Prima...