Sudden Cardiac Death Flashcards
What are the first, second, and third, most common causes of sudden cardiac death in young patients?
- Hypertrophic Cardiomyopathy (HCM) – Most Common Cause
- Anomalous Coronary Arteries – Second Most Common Cause
- Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) -Third Most Common Cause
How is Hypertrophic cardiomyopathy inherited?
Hypertrophic cardiomyopathy (HCM) is an autosomal dominant genetic disorder with incomplete penetrance.
What is the underlying pathophysiology of Hypertrophic cardiomyopathy?
Caused by mutations in sarcomere proteins (e.g., beta-myosin heavy chain, myosin-binding protein C), leading to myocyte disarray, fibrosis, and increased ventricular stiffness.
What is the key histological finding in HCM?
Myocyte hypertrophy and disarray along with interstitial fibrosis due to sarcomere disorder.
What is the normal interventricular thickness and how does this differ from HCM?
This thickness is normally < 1.1 cm and in HCM, the thickness is usually around 2 cm.
What is the posterior wall thickness in patients with HCM?
This can be normal (< 1.1 cm)
What is the classic murmur in HCM?
Harsh crescendo-decrescendo systolic murmur best heard at the left lower sternal border, that increases with valsalva or standing, but decreases with squatting and handgrip.
What specific maneuvers increase symptoms or murmur in HCM and why does this occur?
The murmur is a mid-systolic crescendo decrescendo murmur that accentuates with standing or valsalva.
What allows for differentiation of HCM from aortic stenosis ?
The murmur seen in aortic stenosis decreases with valsalva and standing, while will increase with squatting, leg raise, and handgrip.
What is the pathophysiology of the murmur seen in HCM?
Due to dynamic left ventricular outflow tract (LVOT) obstruction caused by systolic anterior motion (SAM) of the mitral valve.
What are the common symptoms associated with HCM ?
Dyspnea on exertion, chest pain (angina), syncope, palpitations, and sudden cardiac death (especially in young athletes).
How is asymptomatic HCM managed?
Routine monitoring.
Sudden Cardiac Death (SCD) in HCM most commonly are due to ?
Ventricular tachycardia: The increased risk in HCM is related to myocardial disarray and fibrosis, as well as chronic myocardial ischemia resulting from myocardial oxygen supply-demand mismatch. Sustained ventricular tachycardia is the typical cause of sudden cardiac arrest, the most common cause of mortality in HCM.
How is the diagnosis of HCM established?
Echocardiography showing asymmetric septal hypertrophy, systolic anterior motion (SAM) of the mitral valve, and dynamic LVOT obstruction.
What are the common ECG Findings in HCM?
LVH with high voltage QRS, deep narrow Q waves in lateral leads, and T-wave inversions.
Which arrhythmia is most common in patients with HCM?
A fib.
HCM often leads to left atrial enlargement due to diastolic dysfunction, left ventricular outflow tract (LVOT) obstruction, and increased left ventricular filling pressures. These conditions predispose the atrium to atrial fibrillation. AF is associated with a high risk of thromboembolism, including stroke, in patients with HCM. Rate or rhythm control with beta blockers, nondihydropyridine calcium channel blockers, or amiodarone. Anticoagulation (e.g., direct oral anticoagulants or warfarin) is recommended regardless of CHA₂DS₂-VASc score due to the inherent high thromboembolic risk in HCM.
Ablation therapy may be considered in refractory or symptomatic cases.
What is the first-line medical treatment in HCM?
Beta-blockers to reduce heart rate and prolong diastolic filling time.
Why are beta blockers commonly used as a first line treatment for hypertrophic cardiomyopathy?
Beta blockers (eg, metoprolol) are first-line pharmacologic therapy for HCM complicated by LVOT obstruction as they increase LV blood volume to reduce LVOT tract obstruction in 2 ways. First, via negative chronotropy. This increases the diastolic filling time to increase LV end-diastolic volume. Second, via negative inotropy by decreasing contractility to cause blood ejection to complete at a higher LV end-systolic volumes.
What is the second-line medical treatment in HCM, when would this be warranted?
Non-dihydropyridine calcium channel blockers (verapamil) are used to medically manage HCM when beta-blockers are contraindicated. One major contraindication would be patients with asthma. Verapamil is generally preferred over diltiazem because diltiazem has some degree of systemic vasodilatory effects that are undesirable in HCM.
There needs to be a strict avoidance of which medications in the medical management of HCM?
Diuretics because these will worsen LVOT obstruction.
Vasodilators like ACE inhibitors (lisinopril) and Dihydropyridine calcium channel blockers (amlodipine) because these will reduce preload and worsen obstruction. Venous dilation reduces LV preload and arterial dilation reduces afterload, both of which reduce LV blood volume and can worsen LVOT obstruction and symptoms in HCM.
A 34-year-old woman comes to the office due to intermittent palpitations for 2 weeks. The patient has no chest pain or shortness of breath. She was diagnosed with hypertrophic cardiomyopathy 10 years ago and hypothyroidism 5 years ago. The patient takes metoprolol and levothyroxine. Temperature is 37.1 C (98.8 F), blood pressure is 120/80 mm Hg, pulse is 65/min and regular, and respirations are 15/min. Oxygen saturation is 98% on room air. Mucous membranes are moist. Jugular venous pressure is normal. The thyroid gland is symmetrically enlarged and nontender. The lungs are clear to auscultation. A grade 2/6 systolic murmur is heard best at the left sternal border. Complete blood count and serum chemistries are normal. ECG shows normal sinus rhythm with T-wave inversions in the anterior leads, unchanged from 6 months ago. Which of the following is the most appropriate next step in management of this patient?
Periodic ambulatory ECG monitoring (eg, 24-hr Holter monitoring) is indicated in patients with HCM so that arrhythmic complications can be promptly recognized. This monitoring is especially important in those with symptoms suggestive of paroxysmal arrhythmia, as in this patient with palpitations. Evidence of atrial fibrillation on ECG monitoring warrants the initiation of chronic anticoagulation, and evidence of ventricular tachycardia (eg, bursts of nonsustained ventricular tachycardia) may warrant placement of an implantable cardioverter defibrillator.
What are the indications for ICD placement in HCM?
History of ventricular arrhythmias, unexplained syncope, family history of SCD, massive LVH (>30 mm), or abnormal BP response to exercise.
How is HCM differentiated from athlete’s heart?
HCM has abnormal diastolic function and asymmetric hypertrophy, while athlete’s heart has normal diastolic function and symmetric hypertrophy.
What is the surgical management in HCM, and when is this called for?
Septal myectomy or alcohol septal ablation is primarily reserved for refractory symptoms associated with HCM, despite medical therapy.
Which patients are candidates for heart transplantation due to HCM?
Refractory symptoms and Nonobstructive.
What is the second most common cause of sudden cardiac death in young patients?
Anomalous coronary artery
What is the pathophysiology of anomalous coronary artery origin?
Anomalous coronary artery origin, particularly the left coronary artery originating from the right sinus of Valsalva or the right coronary artery originating from the left sinus, creates sharp curvature.
How can you differentiate anomalous coronary artery from Congenital Long QT Syndrome (LQTS) ?
Prolonged QTc (>450 ms in men, >470 ms in women) on ECG.
How can you differentiate anomalous coronary artery from Brugada Syndrome?
Characteristic ST elevation in V1-V3.
What clinical clues suggest Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) in a young patient presenting with sudden cardiac death or exertional symptoms?
Clues include syncope, palpitations, or sudden collapse during exercise in a young individual. Common ECG findings include T-wave inversions in V1-V3 and epsilon waves (small deflections after the QRS complex).
What are the most reliable diagnostic tools for identifying Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) and what are their characteristic findings?
Diagnostic tools include ECG (showing T-wave inversions in V1-V3 and epsilon waves), cardiac MRI (revealing right ventricular dilation and fibrofatty infiltration), and genetic testing for mutations in desmosomal proteins. Biopsy may confirm fibrofatty changes, but it is rarely performed due to invasiveness.
What are the ECG findings characteristic of Long QT Syndrome (LQTS) and how is the QTc interval calculated?
ECG findings include prolonged QTc interval (>450 ms in men, >470 ms in women), with a characteristic notched T wave in some cases. QTc is calculated as QT interval (ms) divided by the square root of the RR interval (seconds).
What are the characteristic ECG findings in Brugada Syndrome and how do they correlate with clinical risk?
Characteristic ECG findings include coved-type ST-segment elevation in leads V1-V3, often followed by a negative T wave. Type 1 Brugada pattern is diagnostic, while Type 2 and Type 3 require further testing. These patterns correlate with the risk of ventricular arrhythmias and sudden death.
