Pacemakers And Strokes: Are They Linked?

Strokes can be caused by malpositioned pacemakers, which can perforate the myocardium, the atrial appendage, or the coronary sinus. However, according to a Northwestern Medicine study, pacemakers can also help identify patients at risk of stroke by measuring atrial fibrillation (AF). AF is the most common heart rhythm disorder in adults and a major contributor to stroke. The study found that increased duration of AF was associated with a higher risk of stroke, even in those with similar stroke risk factors. This information can help doctors make more informed decisions about anti-coagulation treatment.

Pacemakers can help identify patients at risk of stroke

Pacemakers can be used to identify patients at risk of stroke by detecting asymptomatic atrial fibrillation (AF). AF is the most common heart rhythm disorder, affecting 1.5-2% of people in the developed world and increasing the risk of stroke by five-fold.

AF can be detected by placing a wand over a pacemaker to collect information on battery life, and the data can then be used to determine how many patients are currently experiencing AF and how many have episodes of AF but then return to a normal heart rhythm (called sinus rhythm). The risk of stroke in patients with AF can be reduced by around two-thirds with medications that thin the blood, called anticoagulants. However, around a third of patients with AF have no symptoms and do not know they are at increased risk of stroke.

A study of 223 patients who received a pacemaker and did not have AF prior to implantation found that 36 patients had at least one episode of AF detected during follow-up clinics, with 27 of those identified during a routine pacemaker check (12% of the study population). All but one of these patients needed anticoagulation to prevent stroke based on their CHA2DS2-VASc score, which takes into account the most common stroke risk factors.

Another study of 694 patients with dual-chamber pacemakers found that 30% of those without known AF at implant were diagnosed with silent AF during a median follow-up of 38 months. Silent AF was defined as AF detected by a pacemaker that was not identified by the patient or their doctor. The annual stroke incidence was 2.1% in patients with known AF at implant, 1.9% in patients who developed silent AF during follow-up, and 1.4% in patients without AF.

The results of these studies suggest that pacemaker checks can be used to identify patients at risk of stroke and that more frequent monitoring may be beneficial. Remote telemonitoring could also be used to identify AF earlier and initiate anticoagulation to prevent strokes.

Stroke risk in patients with AF is often measured using the CHA2DS2-VASc score

While pacemakers can help to prevent strokes by regulating heart rhythm, they do not completely eliminate the risk of stroke. Strokes can still occur in people with pacemakers due to factors such as atrial fibrillation, malpositioned pacemaker leads, or other underlying health conditions.

Stroke Risk Assessment in Patients with Atrial Fibrillation (AF)

The CHA2DS2-VASc score is a widely used clinical tool for estimating the risk of stroke in people with non-valvular AF. The score takes into account several risk factors, including:

• Congestive heart failure
• Hypertension (blood pressure above 140/90 mmHg or treated with medication)
• Age (65-74, with higher weights for older ages)
• Diabetes mellitus
• Prior stroke, transient ischemic attack, or thromboembolism
• Vascular disease (e.g. peripheral artery disease, myocardial infarction, aortic plaque)
• Sex (female)

Each of these factors is assigned a certain number of points, and the total score corresponds to an estimated risk of stroke. A higher score indicates a greater risk of stroke, while a lower score indicates a lower risk.

The CHA2DS2-VASc score is used to guide physicians in deciding whether to prescribe blood-thinning medications, such as anticoagulants or antiplatelet drugs, to help prevent stroke in people with AF. The score is also used to determine the specific type and dosage of medication that may be appropriate for an individual patient.

The CHA2DS2-VASc score has been recommended by several major medical organizations, including the European Society of Cardiology, the American College of Cardiology/American Heart Association Task Force on Practice Guidelines, and the Heart Rhythm Society. These organizations generally recommend considering anticoagulation prophylaxis for patients with a CHA2DS2-VASc score of 1 or higher, depending on additional factors such as age and sex.

The benefit of stroke prevention with anticoagulants must be balanced against the risk of bleeding associated with their use. To assess this risk, healthcare professionals may use bleeding risk scores such as the HAS-BLED score, which takes into account factors like hypertension, abnormal liver function, bleeding history, and drug or alcohol use.

Sick sinus syndrome patients who develop AF or have a ventricular-demand pacemaker may be at high risk of stroke

Sick sinus syndrome patients who develop AF (atrial fibrillation) or have a ventricular-demand pacemaker may be at high risk of stroke. The risk of embolic stroke during sick sinus syndrome is substantial, and while the risk before pacemaker insertion has been studied, the risk after insertion has not been well studied. However, one study observed that 6% of ischemic stroke patients over a 30-month period had sick sinus syndrome and had a pacemaker inserted 4 days to 112 months before the stroke.

The study found that sick sinus syndrome patients who develop AF or have a ventricular-demand pacemaker might represent high-risk groups for stroke. The annual stroke incidence was found to be 2.1% in patients with known AF at implant, compared to 1.9% in patients who developed silent AF during follow-up, and 1.4% in patients without AF.

Another study found that 30% of patients without known AF at implant were diagnosed with silent AF during follow-up, and that anticoagulation treatment may have significantly decreased the risk of stroke in this patient population.

Overall, while pacemaker implantation can be a successful treatment for sick sinus syndrome, patients should be aware of the risk of stroke, particularly if they are in a high-risk group.

Malpositioned pacemaker leads can cause strokes

The incidence of pacemaker lead malpositioning is rare, and the clinical history of this complication is not well known. However, it is essential to identify and correct malpositioned leads as they can cause significant morbidity and even tragic outcomes. Neurological symptoms following recent pacemaker insertion should raise suspicion of lead malpositioning, especially if a right bundle branch block pattern is observed on electrocardiogram (ECG).

To prevent thromboembolic complications, secure lead placement in the right ventricle is crucial. This can be achieved by introducing the lead with a loop through the tricuspid valve and advancing it into the pulmonary outflow tract or pulmonary artery before pulling it back into the apex of the right ventricle. Routine post-implantation chest radiographs and 12-lead ECGs are essential to identify malpositioned leads early.

In cases of lead malpositioning, lead repositioning is the treatment of choice. However, there are limited data on the procedural risks and no distinct recommendations to improve the safety of these high-risk interventions. Surgical revision of misplaced pacemaker leads is urgent to prevent thromboembolic events, and echocardiography is crucial for post-surgical control.

Device-detected AF can help doctors make more informed decisions about anticoagulation treatment

Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with a major risk of stroke. Treatment with anticoagulation therapy can reduce the risk of stroke, but it also carries the risk of problematic bleeding. For over 60 years, warfarin was the primary treatment for AF. However, in the last decade, a new class of anticoagulants, direct oral anticoagulants (DOACs), have emerged as an alternative. DOACs are easier to take than warfarin but are more expensive.

The decision to initiate anticoagulation therapy involves important trade-offs. Patients must consider the trade-off between the potential for stroke risk reduction and the potential for bleeding. If anticoagulation is chosen, patients must then decide between warfarin or a DOAC.

In 2014, the American Heart Association, American College of Cardiology, and the Heart Rhythm Society formulated a class I recommendation for patients and clinicians to use informed decision-making to individualize patients' antithrombotic care for AF. However, it is unknown how physicians engage AF patients in informed decision-making about anticoagulation in routine care.

In a study that assessed the degree to which physicians engaged AF patients in informed decision-making about anticoagulation, it was found that physicians often presented the alternatives but did not generally engage patients in informed decision-making. The high rate of DOAC prescriptions is likely the result of physician preferences, as patient preferences were rarely assessed.

Physicians should be supported with strategies to engage patients in informed decision-making for anticoagulation. The cost of treatment with DOACs versus warfarin should be discussed by physicians with patients, as unexpected out-of-pocket costs are the primary reason patients abandon drugs at the pharmacy.

Anticoagulation in Device-Detected AF

Among patients with device-detected AF (DDAF), nearly half had concomitant vascular disease at baseline. There was no statistically significant difference in the benefits or risks of anticoagulation therapy between DDAF patients with and without baseline vascular disease. There was a trend towards a greater reduction in the composite of ischemic events among DDAF patients with vascular disease than those without vascular disease.

For patients with clinical AF, anticoagulation is strongly recommended given its clear benefit in reducing stroke and systemic embolism. However, that benefit is less clear for patients with DDAF. This analysis of two key trials explored the benefits and risks of anticoagulation therapy based on the presence or absence of concomitant vascular disease. When pooled together using a meta-analytic approach, the study found a trend towards a greater reduction in the composite of ischemic outcomes in patients with vascular disease compared to those without. Both groups of patients experienced higher risks of bleeding with anticoagulation therapy, but this was only significant for patients with a history of vascular disease.

Based on these findings, anticoagulation therapy should not be recommended routinely for patients with DDAF, even among those with concomitant vascular disease. However, the threshold to start anticoagulation therapy may be lower in patients with concomitant vascular disease if other stroke risk factors are present, and the risk of anticoagulant-related bleeding is sufficiently low.

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