Cardiovascular Drugs — MCQs

Cardiovascular Drugs Indian Medical PG Practice Questions and MCQs

Question 61: Which of the following drugs does not reduce mortality in heart failure with reduced ejection fraction (HFrEF)?

A. Metoprolol
B. Digoxin (Correct Answer)
C. Captopril
D. Potassium-sparing diuretics

Explanation: In the management of Heart Failure with reduced Ejection Fraction (HFrEF), drugs are classified into those that provide **symptomatic relief** and those that provide a **mortality benefit** (prolong life). ### **Why Digoxin is the Correct Answer** **Digoxin** is a cardiac glycoside that inhibits the Na+/K+-ATPase pump, leading to increased intracellular calcium and positive inotropy. While it effectively reduces hospitalizations and improves symptoms (hemodynamics), the **DIG Trial** conclusively showed that it has **no effect on overall mortality**. It is primarily used today for rate control in patients with co-existing Atrial Fibrillation or for refractory symptoms. ### **Explanation of Incorrect Options (Drugs that DO reduce mortality):** * **Metoprolol (Option A):** Specifically **Metoprolol succinate** (extended-release), along with Bisoprolol and Carvedilol, reduces sympathetic overactivity and remodeling, significantly decreasing mortality in stable HFrEF. * **Captopril (Option B):** As an ACE Inhibitor, it prevents the formation of Angiotensin II and the breakdown of bradykinin. ACEIs are the "gold standard" for reducing afterload and preventing cardiac remodeling, thereby improving survival. * **Potassium-sparing diuretics (Option D):** Specifically **Mineralocorticoid Receptor Antagonists (MRAs)** like Spironolactone and Eplerenone. They prevent aldosterone-mediated fibrosis and are proven to reduce mortality in NYHA Class II-IV heart failure. ### **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Mortality-Reducing Drugs:** "**B-A-S-H**" (**B**eta-blockers, **A**CEIs/ARBs/ARNIs, **S**pironolactone/MRAs, **H**ydralazine + Nitrates). * **SGLT2 Inhibitors** (e.g., Dapagliflozin) are the newest addition to the mortality-reducing "Four Pillars" of HFrEF therapy. * **Diuretics (Furosemide)** and **Digoxin** improve symptoms but **do not** improve survival.

Question 62: Which lipid-lowering drug significantly reduces lipoprotein–a levels?

A. Fenofibrate
B. Gemfibrosil
C. Rosuvastatin
D. Nicotinic acid (Correct Answer)

Explanation: **Explanation:** **Correct Answer: D. Nicotinic acid (Niacin)** Nicotinic acid is the most effective conventional lipid-lowering agent for reducing **Lipoprotein(a) [Lp(a)]** levels, typically achieving a reduction of 20–30%. It works by inhibiting the hepatic synthesis of apolipoprotein(a), the key component of Lp(a). While newer agents like PCSK9 inhibitors also reduce Lp(a), Nicotinic acid remains the classic pharmacological answer for this specific effect in medical examinations. **Analysis of Incorrect Options:** * **A & B (Fibrates - Fenofibrate/Gemfibrozil):** These are PPAR-α agonists primarily used to lower triglycerides and increase HDL. They have no significant or consistent effect on Lp(a) levels. * **C (Statins - Rosuvastatin):** Statins are the first-line treatment for lowering LDL-C by inhibiting HMG-CoA reductase. Interestingly, statins do not lower Lp(a) and, in some patients, may even cause a slight paradoxical increase in its levels. **High-Yield Clinical Pearls for NEET-PG:** * **Lp(a) Significance:** It is an independent risk factor for atherosclerosis and aortic stenosis. It is structurally similar to plasminogen and can interfere with fibrinolysis. * **Niacin’s "Best" Profile:** It is the most potent drug for **increasing HDL** levels. * **Side Effects:** The most common side effect is **cutaneous flushing** (mediated by Prostaglandin $D_2$), which can be prevented by taking Aspirin 30 minutes prior. It can also cause hyperuricemia (gout) and hyperglycemia. * **Newer Agents:** PCSK9 inhibitors (e.g., Evolocumab) also significantly reduce Lp(a), but Niacin is the traditional drug of choice for this question.

Question 63: Which of the following drugs is not used for the management of acute pulmonary edema?

A. Norepinephrine
B. Dopamine
C. Dobutamine
D. Phenylephrine (Correct Answer)

Explanation: ### Explanation The primary goal in managing acute pulmonary edema (APE) is to reduce pulmonary venous pressure by improving cardiac output and decreasing preload and afterload. **Why Phenylephrine is the Correct Answer:** Phenylephrine is a **pure $\alpha_1$-adrenergic agonist**. It causes potent systemic vasoconstriction, which significantly increases systemic vascular resistance (SVR) and afterload. In a failing heart (the typical cause of APE), an increase in afterload further reduces stroke volume and increases back-pressure into the pulmonary circulation, potentially worsening the edema. Therefore, it is generally **contraindicated** in APE. **Analysis of Incorrect Options:** * **Dobutamine:** A potent $\beta_1$ agonist with some $\beta_2$ activity. It is an "inodilator" that increases cardiac contractility and reduces afterload, making it a first-line agent for cardiogenic pulmonary edema with low cardiac output. * **Dopamine:** At medium doses (5–10 µg/kg/min), it acts on $\beta_1$ receptors to increase contractility. It is used when APE is accompanied by hypotension. * **Norepinephrine:** While it has $\alpha_1$ effects, its strong $\beta_1$ inotropic effect helps maintain cardiac output in cases of APE associated with severe cardiogenic shock (SBP < 70 mmHg) where maintaining coronary perfusion pressure is critical. **NEET-PG High-Yield Pearls:** * **Mnemonic for APE Management:** **LMNOP** (L-Loop diuretics/Lasix, M-Morphine, N-Nitrates, O-Oxygen, P-Position/Positive pressure ventilation). * **Inotropes vs. Vasopressors:** In APE, we prefer drugs that increase contractility without excessively increasing afterload. * **Phenylephrine Use Case:** It is primarily used for "warm shock" (sepsis) or anesthesia-induced hypotension where the heart is healthy but peripheral resistance is low.

Question 64: What is the treatment for digitalis toxicity?

A. Stoppage of the drug
B. Potassium supplements
C. Fab fragments of digitalis antibodies
D. All of the above (Correct Answer)

Explanation: **Explanation:** Digitalis (Digoxin) toxicity is a medical emergency characterized by a narrow therapeutic index. The management is multifaceted, depending on the severity of the symptoms and electrolyte status. 1. **Stoppage of the drug (Option A):** This is the first and most crucial step in managing any suspected toxicity. Since digoxin has a long half-life (approx. 36–40 hours), immediate cessation prevents further accumulation. 2. **Potassium supplements (Option B):** Digoxin works by inhibiting the Na+/K+ ATPase pump. Hypokalemia increases digoxin binding to this pump, exacerbating toxicity. Correcting low potassium levels helps displace digoxin from the pump and stabilizes the cardiac membrane. *Note: Potassium is contraindicated if the patient is already hyperkalemic.* 3. **Fab fragments (Digibind) (Option C):** This is the **definitive/specific antidote** for life-threatening toxicity. These antibodies bind to free digoxin in the plasma, creating a complex that is excreted by the kidneys. **Why "All of the above" is correct:** Management follows a stepwise approach: stop the drug, correct electrolytes (Potassium/Magnesium), treat arrhythmias (Lidocaine or Phenytoin), and use Fab fragments for severe cases (hemodynamic instability or K+ > 5.5 mEq/L). **High-Yield Clinical Pearls for NEET-PG:** * **Most common arrhythmia:** Ventricular Bigeminy. * **Most characteristic arrhythmia:** Paroxysmal Atrial Tachycardia (PAT) with AV block. * **Visual disturbance:** Xanthopsia (yellow-green halos). * **Drug of choice for Digoxin-induced arrhythmias:** Lidocaine (Phenytoin is also an alternative). * **Avoid:** DC cardioversion (may precipitate VF) and Calcium gluconate (can lead to "Stone Heart").

Question 65: Which of the following is a vasodilator?

A. Hydralazine
B. Minoxidil
C. Nitroprusside (Correct Answer)
D. Nifedipine

Explanation: ### Explanation **Correct Option: C. Nitroprusside** Sodium Nitroprusside is classified as a **balanced vasodilator** (or mixed vasodilator) because it acts equally on both **arterioles and venules**. It works by releasing nitric oxide (NO), which activates guanylyl cyclase, increasing cGMP levels and leading to smooth muscle relaxation. In the context of NEET-PG, it is the drug of choice for hypertensive emergencies due to its rapid onset and short duration of action. **Analysis of Incorrect Options:** * **A. Hydralazine:** This is a **selective arteriolar vasodilator**. It has minimal effect on the venous system. It is commonly used in pregnancy-induced hypertension. * **B. Minoxidil:** This is a potent **selective arteriolar vasodilator** that acts by opening ATP-sensitive $K^+$ channels. It is reserved for refractory hypertension and is notable for causing hypertrichosis. * **C. Nifedipine:** This is a **Dihydropyridine Calcium Channel Blocker (CCB)**. While it causes vasodilation, it is primarily classified as a CCB. In many competitive exams, when "Vasodilator" is used as a specific pharmacological category, it refers to drugs acting via NO or $K^+$ channels rather than CCBs. **High-Yield Clinical Pearls for NEET-PG:** * **Nitroprusside Toxicity:** Prolonged infusion can lead to **Cyanide and Thiocyanate toxicity**. The antidote is Sodium Thiosulfate or Nitrites. * **Steal Phenomenon:** Nitroprusside can cause "Coronary Steal," potentially worsening ischemia in patients with CAD. * **Drug of Choice:** Hydralazine + Methyldopa are preferred in **Pregnancy**; Nitroprusside is preferred in **Aortic Dissection** (along with Esmolol). * **Reflex Tachycardia:** All pure arteriolar vasodilators (Hydralazine, Minoxidil) cause significant reflex tachycardia and fluid retention; they are usually co-administered with Beta-blockers and diuretics.

Question 66: It is essential to give a beta-blocker or Digoxin to increase the refractoriness of the AV node (AVN) prior to administration of which of the following for the treatment of atrial fibrillation?

A. Quinidine
B. Flecainide
C. Moricizine
D. All of the above (Correct Answer)

Explanation: ### Explanation The correct answer is **D. All of the above**. #### Underlying Medical Concept: Paradoxical Tachycardia The primary risk when treating atrial fibrillation (AF) with certain Class I antiarrhythmics is the conversion of AF into **Atrial Flutter with 1:1 AV conduction**, leading to a dangerous increase in ventricular rate. 1. **Vagolytic Effect:** Drugs like **Quinidine** (Class IA) have significant anticholinergic (vagolytic) properties. By inhibiting the vagus nerve, they enhance conduction through the AV node. 2. **Slowing of Atrial Rate:** Class IC agents like **Flecainide** and **Moricizine** (which has properties of IA, IB, and IC) slow the atrial rate. If the atrial rate drops from 300 bpm to 200 bpm, the AV node—which previously blocked many impulses due to its refractory period—may suddenly allow every single impulse to pass through (1:1 conduction). To prevent this life-threatening ventricular tachycardia, an **AV node blocking agent** (Beta-blocker, Verapamil, or Digoxin) must be administered first to increase the refractory period of the AV node. #### Analysis of Options * **A. Quinidine:** Highly notorious for its vagolytic effect. Without prior AV blockade, it can paradoxically increase the heart rate. * **B. Flecainide:** A potent sodium channel blocker that slows atrial flutter cycles, making 1:1 conduction highly likely if the AV node is not suppressed. * **C. Moricizine:** Though less commonly used, it shares Class I characteristics that can facilitate rapid AV conduction during atrial arrhythmias. #### NEET-PG High-Yield Pearls * **Quinidine Syncope:** Caused by *Torsades de Pointes* (due to QT prolongation). * **Cinchonism:** A classic side effect profile of Quinidine (tinnitus, dizziness, headache). * **CAST Trial:** Demonstrated that Class IC drugs (Flecainide) increase mortality in patients with a history of MI or structural heart disease; they are only used in "lone AF" (structurally normal hearts). * **Rule of Thumb:** Always "Control the Rate" (AV node) before "Controlling the Rhythm" (Atria) in AF management.

Question 67: Which drug is responsible for the coronary steal phenomenon?

A. Aspirin
B. Clopidogrel
C. Dipyridamole (Correct Answer)
D. Prasugrel

Explanation: **Explanation** **Coronary Steal Phenomenon** occurs when a drug causes selective vasodilation of healthy coronary arterioles, leading to a diversion of blood flow away from ischemic (stenosed) areas toward well-perfused areas. **Why Dipyridamole is the correct answer:** Dipyridamole is a potent coronary vasodilator that acts by inhibiting adenosine deaminase and phosphodiesterase, leading to increased levels of **adenosine**. In a heart with coronary artery disease, vessels supplying ischemic zones are already maximally dilated by local metabolites to maintain flow. When Dipyridamole is administered, it dilates the vessels in the **non-ischemic** zones. This reduces the resistance in healthy vessels, "stealing" blood flow away from the collateral-dependent ischemic myocardium, potentially worsening ischemia. **Why other options are incorrect:** * **Aspirin:** An irreversible COX-1 inhibitor used as an antiplatelet agent. It does not possess direct vasodilatory properties and thus does not cause coronary steal. * **Clopidogrel & Prasugrel:** These are P2Y12 receptor antagonists (thienopyridines). Their mechanism is strictly antiplatelet (inhibiting ADP-induced platelet aggregation); they do not affect coronary vascular tone. **High-Yield NEET-PG Pearls:** * **Clinical Use:** Due to this phenomenon, Dipyridamole (and Adenosine) is used in **Pharmacological Stress Testing** to identify ischemic areas on imaging. * **Other Drugs:** **Isoflurane** (anesthetic) and **Hydralazine** are also associated with coronary steal. * **Management:** If coronary steal occurs during a procedure, it can be reversed by **Aminophylline** (an adenosine antagonist). * **Dipyridamole Triple Action:** It is an antiplatelet, a vasodilator, and is often used in combination with Aspirin for secondary stroke prevention.

Question 68: What is the mechanism of action of trimetazidine?

A. Fatty acid synthase inhibitor
B. Na channel inhibitor
C. K channel opener
D. Inhibiting mitochondrial LC3-KAT (Correct Answer)

Explanation: **Explanation:** **Mechanism of Action (Correct Answer: D)** Trimetazidine is a metabolic modulator used in the management of chronic stable angina. Its primary mechanism involves the **selective inhibition of long-chain 3-ketoacyl-CoA thiolase (LC3-KAT)**, a key enzyme in the mitochondrial fatty acid $\beta$-oxidation pathway. By inhibiting fatty acid oxidation, the drug shifts myocardial metabolism toward **glucose oxidation**. Since glucose oxidation requires less oxygen per mole of ATP produced compared to fatty acid oxidation, the heart becomes more oxygen-efficient, protecting cardiomyocytes from ischemic injury without affecting heart rate or blood pressure. **Analysis of Incorrect Options:** * **A. Fatty acid synthase inhibitor:** This enzyme is involved in the *synthesis* of fatty acids in the cytosol, not their mitochondrial oxidation for energy. * **B. Na channel inhibitor:** This describes Class I antiarrhythmics (like Lidocaine) or Ranolazine (which inhibits the *late* inward sodium current). * **C. K channel opener:** This is the mechanism of drugs like **Nicorandil** (which also has nitrate-like properties) or Minoxidil. **NEET-PG High-Yield Pearls:** * **Classification:** Trimetazidine is classified as a "pFOX inhibitor" (Partial Fatty Acid Oxidation inhibitor). * **Hemodynamic Neutrality:** Unlike nitrates or beta-blockers, it does not alter heart rate, blood pressure, or coronary blood flow, making it an excellent add-on therapy. * **Side Effects:** A high-yield point for exams is that Trimetazidine can induce **Parkinsonian symptoms** (tremors, rigidity) and gait disturbances, especially in the elderly, due to its ability to cross the blood-brain barrier. It is contraindicated in Parkinson’s disease.

Question 69: Which of the following anti-arrhythmic drugs is useful in AV block resulting from digoxin overdose?

A. Adrenaline
B. Noradrenaline
C. Atropine (Correct Answer)
D. Adenosine

Explanation: ### Explanation **Correct Option: C. Atropine** **Mechanism and Rationale:** Digoxin toxicity causes AV block primarily through two mechanisms: **increased vagal (parasympathetic) tone** and direct depression of the AV node. Atropine is a competitive muscarinic antagonist that blocks the action of acetylcholine at the M2 receptors in the heart. By inhibiting vagal influence, Atropine increases the firing rate of the SA node and enhances conduction velocity through the AV node. Therefore, it is the first-line pharmacological treatment for hemodynamically significant bradycardia or AV block induced by digitalis. **Analysis of Incorrect Options:** * **A & B (Adrenaline and Noradrenaline):** While these are sympathomimetics, they are generally avoided in digoxin toxicity. Digoxin increases intracellular calcium and myocardial excitability; adding catecholamines can further increase ventricular irritability, potentially precipitating fatal ventricular arrhythmias (like Ventricular Tachycardia or Fibrillation). * **D (Adenosine):** Adenosine is used to terminate Supraventricular Tachycardia (SVT) by *slowing* AV conduction. Administering it in a patient who already has an AV block would worsen the condition and could lead to asystole. **High-Yield Clinical Pearls for NEET-PG:** 1. **Definitive Treatment:** The specific antidote for severe digoxin toxicity (life-threatening arrhythmias or hyperkalemia) is **Digoxin-specific antibody fragments (DigiFab/Digibind)**. 2. **Electrolyte Caution:** Hypokalemia, hypomagnesemia, and hypercalcemia predispose a patient to digoxin toxicity. However, digoxin toxicity itself acutely causes **hyperkalemia** (due to inhibition of Na+/K+ ATPase). 3. **ECG Sign:** The most common arrhythmia in digoxin toxicity is **Atrial Tachycardia with AV block**. The most characteristic (though not most common) is Bidirectional Ventricular Tachycardia. 4. **Avoid DC Cardioversion:** Direct current cardioversion is contraindicated in digitalis toxicity as it may precipitate ventricular fibrillation.

Question 70: Statin-induced myopathy is NOT exacerbated by which of the following drugs?

A. Nicotinic acid
B. Enalapril (Correct Answer)
C. Erythromycin
D. Clofibrate

Explanation: **Explanation:** Statins (HMG-CoA reductase inhibitors) are primarily metabolized by the cytochrome P450 system (specifically **CYP3A4**). The most significant adverse effect of statins is skeletal muscle toxicity, ranging from myalgia to life-threatening **rhabdomyolysis**. This risk increases when statins are co-administered with drugs that either inhibit their metabolism or share similar toxic profiles. **1. Why Enalapril is the correct answer:** Enalapril is an **ACE inhibitor** used for hypertension and heart failure. It does not inhibit the CYP3A4 enzyme system, nor does it possess intrinsic muscle toxicity. Therefore, it does not increase the plasma concentration of statins or exacerbate myopathy. **2. Why the other options are wrong:** * **Erythromycin (Option C):** This is a potent **CYP3A4 inhibitor**. It slows down the metabolism of statins (like Simvastatin and Lovastatin), leading to toxic plasma levels and a significantly higher risk of myopathy. * **Clofibrate & Nicotinic Acid (Options D & A):** Both are lipid-lowering agents. Fibrates (especially Gemfibrozil and Clofibrate) and Niacin have independent risks of causing myopathy. When combined with statins, they exert a **synergistic toxic effect** on muscles. Fibrates also inhibit the glucuronidation of statins, further increasing their levels. **High-Yield Clinical Pearls for NEET-PG:** * **Gemfibrozil** is the fibrate with the highest risk of causing myopathy when combined with statins; **Fenofibrate** is considered safer. * **Pravastatin and Rosuvastatin** are not primarily metabolized by CYP3A4, making them safer choices when a patient must take a CYP3A4 inhibitor. * **Checkpoints:** Always monitor **Serum Creatine Kinase (CK)** levels in patients on statins who complain of muscle pain or weakness. Statins should be discontinued if CK levels exceed **10 times** the upper limit of normal.

Practice by Chapter

Antihypertensive Agents

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Drugs for Heart Failure

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Antiarrhythmic Drugs

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Antianginal Agents

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Lipid-Lowering Drugs

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Anticoagulants and Antiplatelet Drugs

Practice Questions

Thrombolytic Agents

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Drugs Used in Pulmonary Hypertension

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Drugs Used in Shock

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Cardiovascular Effects of Non-Cardiovascular Drugs

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