A 72-year-old man comes to the office due to palpitations for the past 1 week. The patient has had no fever, cough, chest pain, or dizziness. Medical history is significant for mild chronic obstructive pulmonary disease, long-standing hypertension, hyperlipidemia, and chronic stable angina. He uses an albuterol/ipratropium inhaler as needed. The patient is a former smoker; he does not use alcohol but drinks 2 or 3 cups of coffee daily. Temperature is 37.1 C (98.8 F), blood pressure is 136/78 mm Hg, pulse is 116/min, respirations are 16/min. Oxygen saturation is 97% on room air. On physical examination, the patient appears comfortable with normal work of breathing. Lung auscultation reveals mildly prolonged expiration with no wheezing or crackles. Cardiac examination shows irregular tachycardia. The remainder of the physical examination is unremarkable. ECG rhythm strip is shown in the exhibit. Which of the following most likely increased the risk of development of this patient's arrhythmia?

Question

A 72-year-old man comes to the office due to palpitations for the past 1 week.  The patient has had no fever, cough, chest pain, or dizziness.  Medical history is significant for mild chronic obstructive pulmonary disease, long-standing hypertension, hyperlipidemia, and chronic stable angina.  He uses an albuterol/ipratropium inhaler as needed.  The patient is a former smoker; he does not use alcohol but drinks 2 or 3 cups of coffee daily.  Temperature is 37.1 C (98.8 F), blood pressure is 136/78 mm Hg, pulse is 116/min, respirations are 16/min.  Oxygen saturation is 97% on room air.  On physical examination, the patient appears comfortable with normal work of breathing.  Lung auscultation reveals mildly prolonged expiration with no wheezing or crackles.  Cardiac examination shows irregular tachycardia.  The remainder of the physical examination is unremarkable.  ECG rhythm strip is shown in the exhibit.  Which of the following most likely increased the risk of development of this patient's arrhythmia?

Quizplus · Accepted Answer

11ec25c8_d2d8_7253_bc81_fba90cbf754e_MD0003_00 This patient's ECG rhythm strip shows a rapid rhythm with irregularly irregular R-R intervals and an absence of organized P waves, consistent with atrial fibrillation with rapid ventricular response (ie, rate >100/min). The pathogenesis of atrial fibrillation involves an underlying substrate created by atrial remodeling, or changes in the atrial structure and conduction system that result from aging and comorbidities. Chronic hypertension is the most common comorbidity associated with atrial fibrillation and is likely one of the strongest contributors to atrial remodeling. ECG Most of the contribution of chronic hypertension to atrial remodeling is likely via left atrial dilation. With the left ventricle pumping against chronically increased pressure load, compensatory concentric left ventricular (LV) hypertrophy develops, which decreases LV diastolic filling. Given the thin left atrial walls, even subtle pressure increases transmitted back to the left atrium can have a significant effect on left atrial stretching and dilation. The left atrial stretching likely also contributes to atrial fibrosis and some degree of atrial conduction remodeling. Chronic obstructive pulmonary disease (COPD) can also contribute to atrial fibrillation in several ways. Severe COPD associated with significant hypoxemia can cause right atrial dilation due to hypoxic pulmonary vasoconstriction and resulting pulmonary hypertension. In addition, COPD exacerbation can increase sympathetic tone and act as a trigger for atrial fibrillation. Beta-2 agonists (eg, albuterol, salmeterol) used for the treatment of COPD may also be occasional triggers of atrial fibrillation. However, the underlying substrate (created by chronic hypertension in this patient) is a more important factor (Choice B). (Choice A) Acquired long QT syndrome typically results from medications that prolong the QT interval. It increases the risk of polymorphic ventricular tachycardia (ie, torsade de pointes), but it is not a contributor to atrial fibrillation. medications (Choice C) Despite the common belief that caffeine consumption is considered a trigger for atrial fibrillation and other arrhythmias (due to increased sympathetic tone), studies have not shown any significant association. (Choice E) Coronary artery disease (CAD) and its associated risk factors (eg, diabetes mellitus, smoking) likely somewhat contribute to atrial remodeling but less so than chronic hypertension. In patients with atrial fibrillation, the association of CAD with the arrhythmia is primarily seen among those who develop acute myocardial infarction or ischemic heart failure. Educational objective: Chronic hypertension is the most common comorbidity associated with atrial fibrillation and is likely one of the strongest contributors to the predisposing atrial remodeling. Aging is also a strong contributor. References: The natural history of atrial fibrillation: incidence, risk factors, and prognosis in the Manitoba follow-up study. (http://www.ncbi.nlm.nih.gov/pubmed/7733127) Atrial fibrillation in hypertension: predictors and outcome. (http://www.ncbi.nlm.nih.gov/pubmed/12574085)

A 72-Year-Old Man Comes to the Office Due to Palpitations