Chieng D, Paul V, Denman R. Current Device Therapies for Sudden Cardiac Death Prevention – the ICD, Subcutaneous ICD and Wearable ICD. Heart, Lung and Circulation. 2019;28(1):65‐75.
https://www.heartlungcirc.org/article/S1443‐9506(18)31920‐6/fulltext
21. Answer: D
This patient has infrequent palpitations which happen around once every 6 months. Three‐ or seven‐day Holter monitoring may not capture arrythmias due to the infrequent events.
It is important to know the frequency of palpitations or syncopal events to decide what the best way is to investigate potential underlying arrhythmias.
The next preferred step of investigation for this patient is an implantable loop recorder due to the infrequent symptoms and the long duration between events.
It will be important to investigate underlying coronary artery disease in this patient with significant risk factors for cardiovascular disease due to his past medical history, which may contribute to his symptoms.
In patients with infrequent unexplained syncopal episodes, implantable loop recorders have high rates of diagnosing arrythmias compared to external loop recorders or physician follow‐up. Implantable loop recorders are pen drive sized device inserted under the skin under local anaesthetic and are capable of recording cardiac events for up to three years. Implantable loop recorders can be considered in patients with cryptogenic stroke to detect paroxysmal or infrequent atrial fibrillation if the initial in‐hospital or Holter monitoring are unable to detect atrial fibrillation, which is a risk factor for embolic stroke.
Wearable devices are gaining popularity in the recent years and may aid in detection of arrythmias such as atrial fibrillation and supraventricular tachycardia. However, in patients with syncopal episodes, they are unable to record these events due to potential loss of consciousness with syncope. More studies are required to see how to integrate smart devices to improve patient care.
Khalil C, Haddad F, Al Suwaidi J. Investigating palpitations: the role of Holter monitoring and loop recorders. BMJ. 2017; 358: j3123.
https://www.bmj.com/content/358/bmj.j3123.long
22. Answer: A
Evolocumab and alirocumab are monoclonal antibodies inhibiting Proprotein Convertase Sublitisin/Kexin Type‐9 (PCSK9). PCSK9 inhibits low‐density lipoproteins (LDL) receptor recycling, which in turn limits the ability for tissue to sequester LDL from the extracellular space. Individuals with activating mutations of the PCSK9 gene have high LDL and poor cardiac outcomes; conversely individuals with inactivating mutations of the PCSK9 gene have low LDL levels and relatively good cardiac outcomes. PCSK9 inhibitor therapy is administered by subcutaneous injection and is indicated where statin/combination therapy has failed to reach LDL targets. PCKS9 inhibitors have shown small but meaningful reductions in cardiovascular risk and mortality and have a greater protective effect for individuals with higher baseline LDL.
The primary action of statins (eg. rosuvastatin) is to decrease hepatocyte production of cholesterol by inhibition of HMG‐CoA (3‐hydroxy‐3‐methylglutaryl‐coenzyme A) reductase, thereby increasing LDL receptor synthesis, and increasing LDL clearance. Ezetimibe is an azetidinone cholesterol absorption inhibitor, which acts by blocking NPC1L1 (Niemann‐Pick C1‐Like 1) a key brush‐border transport protein. Mipomersen is an example of a newer advance in lipid‐lowering therapy, which inhibits synthesis of apoB‐100 and LDL, and can be considered for use in homozygous familial hypercholesterolaemia but hepatotoxicity is a significant potential adverse effect.
Burnett J, Hooper A. PCSK9 — A Journey to Cardiovascular Outcomes. New England Journal of Medicine. 2018;379(22):2161–2162.
https://www.nejm.org/doi/full/10.1056/NEJMe1813758
23. Answer: B
Long QT syndrome (LQT) is diagnosed by QT prolongation and T‐wave abnormalities on an ECG. A QT interval is measured from the onset of the QRS complex to the end of the T wave. The corrected QT interval (QTc, corrected for heart rate) can be calculated as QTc = QT interval + square root of the RR interval. The latest European Society of Cardiology guideline suggests upper limits of the QT interval of 480 ms on the ECG strip, regardless of gender. Presenting symptoms of LQT include dizziness, syncope, seizures, and in some cases cardiac arrest due to the presence of Torsades‐de‐Pointes which can degenerate to ventricular fibrillation causing sudden cardiac death. LQT can be congenital or acquired. LQT is associated with multiple risk factors, including a family history of LQT, ion channel abnormalities, structural heart disease, heart failure, advanced age, hypokalaemia, subarachnoid bleed, medications, diabetes, epilepsy, emotional stress, and physical stress, etc.
The aim of the treatment of LQT is to ensure patients are symptom free. The mainstay of management of LQT is beta blockers in both asymptomatic and symptomatic patients with LQT. Medication compliance is important to avoid life‐threatening consequences. Unfortunately, cardiac events cannot be completely prevented by taking beta blockers.
Life‐style modification such as avoiding strenuous exercises, emotional stress, physical stress, sleep disturbance, and medications that prolong the QT interval, should be implemented as much as possible.
ICD should be considered in symptomatic patients with syncope who are already on beta blockers, high risk patients with a very long QTc interval (> 550 ms), patients with T‐wave alternans, or in patients who cannot tolerate beta blocker therapy. If there are reversible causes of LQT, an ICD is not indicated.
Left cardiac sympathetic denervation (LCSD) is a rarely performed but effective procedure for management of LQT in patients who cannot have beta blockers or ICD. LCSD procedure involves high thoracic left sympathectomy and ablation of the lower half of the stellate ganglion along with T2 to T4. It reduces noradrenaline release at the ventricles and increase the threshold for ventricular fibrillation.
Shah S, Park K, Alweis R. Long QT Syndrome: A Comprehensive Review of the Literature and Current Evidence. Current Problems in Cardiology. 2019;44(3):92–106.
https://www.sciencedirect.com/science/article/abs/pii/S0146280618300513?via%3Dihub
24. Answer: D
This patient is likely to have a history of rheumatic fever leading to mixed mitral valve disease. She is symptomatic with pulmonary hypertension which is the indication for intervention. The mortality for untreated symptomatic severe mitral stenosis is 85% over 10 years. Complications for untreated severe mitral stenosis include endocarditis, atrial fibrillation, stroke, pulmonary hypertension, and right heart failure. The clinical features of severe mitral stenosis are:
Transmitral mean gradient >10 mmHg
