How should I treat a patient with tachycardia (heart rate 165) at a rapid response?

From the Guidelines

For a patient with tachycardia (heart rate 165) during a rapid response, the initial step is to assess the patient's stability, and if unstable, prepare for immediate synchronized cardioversion, while for stable patients, vagal maneuvers or adenosine administration are recommended as first-line treatments, according to the 2015 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia 1. The assessment of stability is crucial because it guides the choice between immediate intervention for unstable patients and a more nuanced approach for stable ones. For unstable patients, signs such as shock, altered mental status, chest pain, or hypotension indicate the need for urgent action, typically starting with synchronized cardioversion at 100-200 joules. In contrast, stable patients can undergo further evaluation, including a 12-lead ECG to differentiate between narrow complex and wide complex tachycardias. For narrow complex tachycardia, which is likely supraventricular in origin, initial management includes vagal maneuvers like the modified Valsalva maneuver. If vagal maneuvers are unsuccessful, adenosine 6 mg IV push, followed by a 20 mL saline flush, is recommended, with a potential second dose of 12 mg if needed, as supported by the guideline 1. The choice of adenosine is based on its effectiveness in terminating supraventricular tachycardias, particularly those of reentrant mechanisms, and its diagnostic utility in differentiating between types of tachycardia. For patients with atrial fibrillation, rate control using metoprolol 5 mg IV over 2-5 minutes or diltiazem 0.25 mg/kg IV over 2 minutes can be considered. In cases of stable wide complex tachycardia, consultation with cardiology and consideration of amiodarone are recommended. Throughout the management process, continuous cardiac monitoring, secure IV access, oxygen administration as needed, and addressing underlying causes are essential components of care. The primary goal is to reduce the heart rate and improve cardiac output, thereby minimizing morbidity, mortality, and improving the patient's quality of life, as emphasized by the most recent and highest quality guidelines available 1. Key considerations include the patient's hemodynamic stability, the specific type of tachycardia, and the potential side effects of treatments, all of which are addressed in the guideline recommendations 1.

From the FDA Drug Label

Diltiazem slows the ventricular rate in patients with a rapid ventricular response during atrial fibrillation or atrial flutter Diltiazem converts paroxysmal supraventricular tachycardia (PSVT) to normal sinus rhythm by interrupting the reentry circuit in AV nodal reentrant tachycardias and reciprocating tachycardias, e.g., Wolff-Parkinson-White syndrome (WPW). In patients with atrial fibrillation and atrial flutter, a significant correlation was observed between the percent reduction in HR and plasma diltiazem concentration using the Sigmoidal Emax model Based on this relationship, the mean plasma diltiazem concentration required to produce a 20% decrease in heart rate was determined to be 80 ng/mL.

To treat a patient with tachycardia (heart rate 165) at a rapid response, consider administering diltiazem (IV), as it can slow the ventricular rate in patients with a rapid ventricular response during atrial fibrillation or atrial flutter, and convert paroxysmal supraventricular tachycardia (PSVT) to normal sinus rhythm. The goal is to achieve a 20% decrease in heart rate, which corresponds to a mean plasma diltiazem concentration of 80 ng/mL 2. Key points to consider:

• Diltiazem can selectively reduce the heart rate during tachycardias involving the AV node
• Diltiazem has no significant electrophysiologic effects on tissues in the heart that are fast sodium channel dependent
• Monitor the patient's heart rate and adjust the diltiazem dose accordingly to achieve the desired effect.

From the Research

Treatment Approach for Tachycardia

The patient's heart rate of 165 indicates tachycardia, which requires immediate attention. The treatment approach depends on the underlying cause of the tachycardia and the patient's hemodynamic stability.

Hemodynamically Unstable Patients

• For hemodynamically unstable patients with supraventricular tachycardia, intravenous adenosine is the drug of choice 3.
• Adenosine has been shown to effectively terminate paroxysmal supraventricular tachycardia (PSVT) in emergency department patients, with a success rate of 96% 4.

Hemodynamically Stable Patients

• For hemodynamically stable patients with atrial fibrillation or atrial flutter and a rapid ventricular rate, treatment options include intravenous beta-adrenergic blocking drugs, amiodarone, verapamil, or diltiazem 3.
• A meta-analysis comparing intravenous diltiazem and metoprolol for acute rate control of atrial fibrillation/flutter and rapid ventricular response found that diltiazem was more effective in randomized trials, but not in observational studies 5.
• Another study found that metoprolol was associated with a 26% lower risk of adverse events compared to diltiazem 6.

Administration Route

• Intravenous administration of metoprolol has been shown to be more effective than oral administration in preventing atrial fibrillation after cardiac surgery 7.

Key Considerations

• The choice of treatment should be based on the patient's specific condition, medical history, and current medications.
• Close monitoring of the patient's heart rate, blood pressure, and overall clinical status is crucial during treatment.