Saturday, January 20, 2024

Special circumstances where warfarin is favored over DOACs

 When is warfarin favored over DOACs?

 Valvular atrial fibrillation

This term is becoming obsolete. For anticoagulation for stroke prevention in atrial fibrillation  DOACs are contraindicated and warfarin favored in severe rheumatic mitral stenosis and mechanical prosthetic valves.

Liver disease. 

If Child Pugh is C DOACs are not recommended. If B, apixaban and rivaroxaban can be used “with caution” (FDA labeling ).   Child Pugh calculator.

 Antiphospholipid syndrome. 

Warfarin is favored (Up to Date). 

Morbid obesity: 

DOAC is okay for BMI up to 40. Above 40 rivaroxaban and apixaban are acceptable but other DOACs should be avoided. 

History of gastrectomy or weight loss surgery: 

Warfarin preferred. This review summarizes the rationale and recommendations regarding morbid obesity and patients who have had weight loss surgery.

In addition, certain drug interactions with DOACs are category X thus prohibiting use.

ACC atrial fibrillation guidelines 2023

 A few key points from the 2023 atrial fibrillation guidelines American College of Cardiology

New classification: 

The old classification is maintained but it is encompassed in a broader classification outlining the stages of risk and /or the occurrence of atrial fibrillation. 

Stage 1:  at risk. This refers to the presence of risk factors such as obesity and hypertension. 

Stage 2: pre atrial fibrillation encompassing structural abnormalities such as LAE or warning arrhythmias such as  atrial ectopy.

Wiithin atrial fibrillation itself the traditional categories of paroxysmal persistent and permanent remain. Right above permanent atrial fibrillation is another designation referring to successful ablation. 

Flexibility is built into the CHA₂DS₂-VASc score for anticoagulation decisions. 

If the risk is intermediate there is considerable equipoise and shared decision making is advised. 

Increased preference for early rhythm control.

There is an increased emphasis on early rhythm control especially in patients with heart failure and reduced injection fraction. Catheter ablation via pulmonary vein isolation now he has a class 1 indication particularly in patients with who present with heart failure and reduced ejection fraction at the time of the onset of atrial fibrillation detection.   Specifically:

Rhythm control recommended over rate control if decreased left ventricular function and persistent or high burden atrial fibrillation, class 1 

If atrial fibrillation is symptomatic, class 2a. 

Specific arrhythmias related to fibrillation have been defined. 

Atrial tachycardia is defined as a rate greater than or equal to 100, non sinus. Mechanisms can be automaticity, triggered or micro reentry  Atrial flutter. is considered any tachyarrhythmia  that involves macro re-entry. Typical flutter involves macro reentry that goes through the cavo tricuspid isthmus. All others are considered atypical.

Caffeine avoidance is noted not to be beneficial. 

The designation of valvular versus non-value or atrial fibrillation has become obsolete. 

The recommendation now is that for a mechanical prosthesis or severe rheumatic mitral stenosis warfarin is recommended.  DOACs are preferred for all other patients unless there are certain disease-related or pharmacokinetic contraindications. 

In cases of cryptogenic stroke there is a 2a recommendation for extended monitoring. The guidelines do not specify the duration of monitoring. 

For device detection of high rate episodes, (specifically pacemaker detection), stroke risk is believed to exist but believed to be less than that of clinical episodes. 

If a high rate episode is detected and lasts greater than or equal to 5 minutes it is almost always atrial fibrillation. For device detection of high rate episodes lasting greater than or equal to 24 hours systemic anticoagulation is given a 2a recommendation.   For the range of 5 minutes to 24 hours this same situation has a 2b recommendation. In both cases there is considered to be sufficient equipoise that shared decision making applies.

Atrial appendage occlusion devices such as the Watchman have a 2a recommendation if CHA₂DS₂-VASc  is greater than or equal to 2 and anticoagulation is contraindicated. 

For high bleeding risk but not a contraindication the device is given a 2b recommendation. 

There are some changes in systemic anticoagulation recommendations for varying degrees of kidney disease. 

Up to and including stage 3 systemic anticoagulation if otherwise recommended for atrial fibrillation has a class 1 recommendation. It drops to class 2a for stage 4 and to 2B if there is  esrg/hd. 

In atrial fibrillation with rheumatic valve disease or mechanical prosthesis for which vitamin K antagonist anticoagulation is recommended the CHA₂DS₂-VASc  score does not apply. 

The long-term rate control goal is an upper rate limit of 100-110 and has a 2a recommendation. 

Acute rate control

If EF is greater than 40, IV beta blocker or non-dihydropyridine calcium blocker, class 1.  Digoxin  if above ineffective or contraindicated class 2a. 

IV mag sulfate class 2a. It may be better than standard agents. Up to five grams is considered low dose. Occasionally one could use greater than or equal to 5 g.  The main use is adjunctive.

Amiodarone if others ineffective or contraindicated, class 2b.

AVN ablation indications

AV node ablation if rate control is refractory to medication and the patient is otherwise a candidate, 2a. This will be combined with pacing obviously and initial lower rate limit, to avoid malignant ventricular arrhythmia, should be set at 80 to 90 with plans to program down by monthly decrements of 10 until 60 is reached. 

 Stroke prevention associatied with cardioversion 

 If atrial fibrillation could have been going on greater than or equal to 48 hours 3 weeks of anticoagulation first or tee prior to cardioversion and anticoagulation for greater than or equal to 4 weeks afterwards. 

 Drugs to maintain sinus rhythm long-term. 

The guidelines are not very explicit about whether drugs should even be used in the first place. They merely say that such are “ reasonable “  for patients who are " not candidates for, or decline” ablation. Similarly those who prefer antiarrhythmic therapy to ablation are considered reasonable candidates. The implication is that you should probably do something to maintain sinus rhythm. 

If normal EF and no structural heart disease and no coronary disease then fleccanide or propofanone 2a

Dronedarone 2a if no recent decompensated HR and if HF class II or better.

Dofetilide 2a if no long QT or torsades risks and no hypokalemia or hypomag, or tendency thereto.

Amiodarone  is 2a but the agents above may be preferable. 

Sotalol is 2b with the same precautions that apply to dofetilide. 

In pts with prior MI, structural disease or EF less than or equal to 40% no recent decompensation or functional class III or worse, dronedarone is 2a.

When does antiarrhythmic therapy need to be administered in the hospital?  And for how long?

Dofetilide 3 d

Sotolol, admit to hospital but the guideline does not specify how long.

ICs:  Observe at least after the first dose.

PVI catheter ablation (pulmonary vein isolation ):

if antiarrhythmics not tolerated, contraindicated or not preferred, class 1.  For younger patients with no or few comorbidities class 1 as  first line even if the atrial fibrillation is paroxysmal. 

For atrial flutter, class 1 ( it would be implied that this is typical flutter ). For a new diagnosis of atrial fibrillation in heart failure with reduced ejection fraction both at the same time early rhythm control is class 1 and ablation is said to be “ beneficial when appropriate” class 1.