What is ischemic heart disease and why is it a contraindication for flecainide in a 67‑year‑old man?

What is Ischemic Heart Disease and Why is it a Contraindication for Flecainide?

Definition of Ischemic Heart Disease

Ischemic heart disease (IHD) is a condition caused by reduced blood flow to the heart muscle, most commonly due to atherosclerotic plaque formation in the epicardial coronary arteries that creates stenotic lesions limiting coronary blood flow, particularly during increased myocardial oxygen demand. 1

Primary Pathophysiological Mechanisms

• Atherosclerotic plaque buildup in coronary arteries creates fixed obstructions that restrict blood flow, especially when the heart requires more oxygen during exertion or stress 1
• Plaque rupture with superimposed thrombosis can acutely compromise coronary flow, leading to acute myocardial ischemic syndromes including myocardial infarction 1
• The severity and distribution of coronary stenoses directly influence both prognosis and symptom burden 1

Clinical Manifestations

• Typical angina pectoris remains the most common presentation, though elderly patients and those with diabetes may present with atypical symptoms including dyspnea, worsening heart failure, or even silent ischemia 2
• Patients with diabetes and autonomic neuropathy frequently experience silent ischemia where ischemic episodes produce no anginal symptoms 1
• At coronary arteriography, elderly individuals demonstrate more extensive coronary artery disease, more multivessel disease, and more coronary artery calcification 2

Why Flecainide is Contraindicated in Ischemic Heart Disease

Flecainide is absolutely contraindicated in patients with a history of myocardial infarction and should be avoided in those with structural heart disease, particularly active ischemia, because it increases mortality and proarrhythmic risk. 2

The Evidence Behind the Contraindication

• The Cardiac Arrhythmia Suppression Trial (CAST) established that flecainide increases mortality in post-myocardial infarction patients, leading to its contraindication in structural heart disease since 1991 3
• In patients with complex adult congenital heart disease, flecainide was associated with proarrhythmia in 5.8% of patients and sudden cardiac arrest in 3.9% 2
• The mechanism involves flecainide's class IC antiarrhythmic properties, which can precipitate life-threatening ventricular arrhythmias in the setting of ischemic myocardium 4, 3

Important Clinical Nuances for a 67-Year-Old Man

For your 67-year-old patient, the key distinction is whether he has active ischemia or prior myocardial infarction versus stable, nonobstructive coronary disease:

• Absolute contraindications include history of myocardial infarction, active myocardial ischemia, heart failure, or depressed left ventricular ejection fraction 2, 4
• Recent observational data suggest flecainide may be safe in highly selected patients with stable, nonobstructive coronary artery disease without active ischemia and preserved ventricular function, though this remains controversial and requires randomized controlled trials for confirmation 4, 3
• A 2021 study found no increased mortality or ventricular arrhythmias in low-risk patients with stable nonobstructive CAD treated with flecainide for at least 1 year 4

Risk Factors That Increase Concern

Several conditions common in a 67-year-old man substantially increase the risk of ischemic heart disease and would make flecainide particularly dangerous:

• Hypertension increases left ventricular wall tension and oxygen consumption 1
• Diabetes mellitus significantly increases IHD probability and is associated with silent ischemia 1
• Smoking, hyperlipidemia, and physical inactivity independently accelerate atherosclerosis 1
• Age itself is a major risk factor, with men having higher risk at younger ages than women 1

Critical Clinical Pitfalls to Avoid

• Never prescribe flecainide without first excluding structural heart disease, particularly prior myocardial infarction, through careful history, ECG, and echocardiography 2, 4
• Do not assume absence of symptoms means absence of ischemia—silent ischemia is common, especially in diabetic patients 1
• If considering flecainide in a patient with any coronary disease, ensure there is no active ischemia, preserved ventricular function, and stable disease documented by recent stress testing or angiography 4, 3
• For patients with hypertension and left ventricular hypertrophy (wall thickness ≥1.4 cm), flecainide poses increased proarrhythmic risk and should be avoided 2

Alternative Antiarrhythmic Approaches in IHD

For patients with ischemic heart disease requiring rhythm control, safer alternatives include:

• Beta-blockers are first-line for rate control and have proven mortality benefit in patients with CAD, angina, prior MI, or heart failure 2, 5
• Amiodarone is generally reserved for refractory cases but has a better safety profile than flecainide in structural heart disease, though it carries significant long-term toxicity risks 2
• Sotalol combines beta-blocking activity with antiarrhythmic efficacy and is appropriate for patients with ischemic heart disease unless heart failure is present 2