Pharmacotherapy Case Study: Ventricular Arrhythmia by Dr. Nehad Ahmed
Patient Profile: 52-year-old male
Subjective Data
Chief Complaint: “My heart races out of nowhere, and I almost passed out yesterday.”
History of Present Illness:
Recurrent episodes of sudden-onset palpitations lasting 2–5 minutes, accompanied by dizziness and chest discomfort.
One near-syncopal episode 24 hours ago while watching TV.
No prior history of arrhythmia. Self-treated with rest; symptoms resolve spontaneously.
Medical History:
Hypertension (8 years), myocardial infarction (3 years ago, treated with PCI to LAD).
LVEF 35% on last echocardiogram (6 months ago).
Non-adherent to carvedilol and lisinopril due to fatigue.
Medications:
Carvedilol 6.25 mg BID (takes “a few times a week”).
Aspirin 81 mg daily, atorvastatin 40 mg daily.
Social History:
Smokes ½ pack/day × 20 years.
Alcohol: 4–5 beers/week.
Denies illicit drug use.
Family History: Father died of sudden cardiac arrest at age 55.
Objective Data
Vitals:
BP: 138/88 mmHg, HR: 112 bpm (irregular), RR: 18/min, SpO₂: 96% on room air.
BMI: 28 kg/m².
Physical Exam:
Cardiovascular: Irregular rhythm, no murmurs.
Lungs: Clear bilaterally.
Neurologic: Alert, no focal deficits.
Diagnostic Studies:
ECG: Monomorphic ventricular tachycardia (rate 180 bpm, wide QRS >140 ms).
Labs:
K⁺: 3.2 mEq/L (low), Mg²⁺: 1.6 mg/dL (low), troponin: negative.
TSH: Normal.
Echocardiogram: LVEF 30%, anterior wall akinesis.
Telemetry: Non-sustained VT episodes (4–6 beats) during hospitalization.
Assessment
Primary Diagnosis:
Sustained Monomorphic Ventricular Tachycardia (secondary to ischemic cardiomyopathy).
Secondary Prevention Indication (reduced LVEF + prior MI).
Contributing Factors:
Hypokalemia, hypomagnesemia, non-adherence to beta-blockers.
Smoking, family history of sudden cardiac death.
Pharmacotherapy Plan
Acute Management:
Synchronized Cardioversion (for hemodynamically unstable VT).
Correct Electrolytes:
IV Potassium Chloride (target K⁺ >4.0 mEq/L).
IV Magnesium Sulfate 2 g (even if Mg²⁺ normal).
Antiarrhythmic:
Amiodarone 150 mg IV bolus, followed by 1 mg/min infusion ×6 hours.
Long-Term Management:
Beta-Blocker Optimization:
Carvedilol 12.5 mg BID (titrate to 25 mg BID; improves survival in cardiomyopathy).
Antiarrhythmic Therapy:
Amiodarone 200 mg daily (reduce dose after 1 week; monitor thyroid/LFTs).
ICD Implantation (Class I recommendation for secondary prevention).
Adjunctive Therapy:
ACE Inhibitor: Lisinopril 10 mg daily (titrate to 40 mg; reduces LV remodeling).
Aldosterone Antagonist: Spironolactone 25 mg daily (if K⁺ <5.0 mEq/L).
Non-Pharmacologic Interventions:
Smoking Cessation: Refer to quitline; prescribe varenicline.
Cardiac Rehabilitation: Supervised exercise program.
Monitoring
Continuous Telemetry: Assess for recurrent VT/VF.
Daily Labs: K⁺, Mg²⁺, renal function (adjust electrolytes as needed).
Amiodarone Monitoring: Thyroid function (TSH), LFTs, baseline chest X-ray.
ICD Interrogation: Quarterly checks post-implantation.
Patient Education
Medication Adherence: Stress carvedilol/amiodarone to prevent sudden death.
Avoid Triggers: Caffeine, alcohol, smoking.
Emergency Plan: Use of ICD, seek care for prolonged palpitations or syncope.
Rationale
Amiodarone is preferred for ventricular arrhythmias in structural heart disease due to lower proarrhythmic risk.
Carvedilol reduces mortality in heart failure and suppresses sympathetic-driven arrhythmias.
ICD is lifesaving for secondary prevention of sudden cardiac death.
Electrolyte Correction addresses reversible triggers of VT (hypokalemia/hypomagnesemia).
Smoking Cessation reduces ischemic burden and arrhythmia recurrence.
Key Considerations:
Avoid Class IC antiarrhythmics (e.g., flecainide) in ischemic cardiomyopathy.
Monitor for amiodarone toxicity (pulmonary fibrosis, thyroid dysfunction).
Address non-adherence through pill organizers and counseling.
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