What constitutes a rapid ventricular rate?

What Constitutes Rapid Ventricular Rate

Rapid ventricular rate is defined as a heart rate greater than 100 beats per minute, with rates above 150 beats per minute more likely to cause hemodynamic compromise and symptoms. 1, 2

Definition and Classification

• Ventricular tachycardia (VT) is defined as three or more consecutive complexes originating from the ventricles at a rate greater than 100 beats per minute 1, 3
• For atrial fibrillation (AF), adequate rate control is generally defined as:
  • 60-80 beats per minute at rest 1
  • 90-115 beats per minute during moderate exercise 1
• In the AFFIRM trial, adequate control was defined as an average heart rate up to 80 beats per minute at rest and either an average rate up to 100 beats per minute over at least 18-hour Holter monitoring or a maximum heart rate of 110 beats per minute during a 6-minute walk test 1
• In the RACE trial, rate control was defined as less than 100 beats per minute at rest 1

Clinical Significance of Rapid Ventricular Rate

• Heart rates <150 beats per minute are unlikely to cause symptoms of instability unless there is impaired ventricular function 1, 2
• Sustained, uncontrolled tachycardia may lead to deterioration of ventricular function (tachycardia-related cardiomyopathy) 1
• In patients with AF, rapid ventricular rates can cause:
  • Inadequate time for ventricular filling 1
  • Rate-related ischemia 1
  • Impaired hemodynamics 1
• Ventricular rates ≥100 bpm in patients with AF are associated with greater risk of both new-onset heart failure and all-cause mortality 4

Ventricular Rate Thresholds and Clinical Outcomes

• Rates >140 beats per minute at rest in AF are consistently associated with compromised cardiac output 5
• Rates between 90-140 beats per minute in AF may be controlled or uncontrolled depending on individual cardiac function 5
• Rates <90 beats per minute in AF are generally considered controlled 5
• For VT, sustained is defined as lasting >30 seconds or requiring termination due to hemodynamic compromise in <30 seconds 1, 3
• Nonsustained VT is defined as ≥3 beats, terminating spontaneously in <30 seconds 1, 3

Management Considerations

• Patients who are symptomatic with rapid ventricular rates during AF require prompt medical management 1
• Cardioversion should be considered if symptomatic hypotension, angina, or heart failure is present 1
• When cardiac function is poor, cardiac output can be dependent on a rapid heart rate, so "normalizing" the heart rate can sometimes be detrimental 1
• For hemodynamically unstable VT, synchronized cardioversion is recommended regardless of the duration 3

Monitoring and Assessment

• It may be useful to evaluate heart rate response to submaximal or maximal exercise or monitor rate over an extended period (e.g., 24-hour Holter recording) 1
• Rate variability during AF provides information about autonomic nervous system status that may have independent prognostic implications 1
• A target ventricular rate of 90 beats per minute in patients with AF at rest would result in control with the least compromise of cardiac output 5

Caveats and Pitfalls

• Rapid heart rates may be a physiological response to stressors such as fever, anemia, or hypotension/shock rather than a primary arrhythmia 1, 2
• In patients with poor ventricular function, even rates <150 beats per minute can cause symptoms and hemodynamic compromise 1, 2
• When treating rapid ventricular rates, always assess for and address underlying causes rather than simply targeting the heart rate 2