Abstract

This article discusses two patients, a 44-year-old woman and an 82-year-old man who presented to our clinic with newly diagnosed asymptomatic heart blocks. While newly discovered 2nd degree (type II) and 3rd degree heart blocks in the primary care setting may cause referral to cardiologists for a pacemaker implantation, not all patients with heart blocks need pacemakers. We report 2 patients that were referred to a cardiologist for pacemaker implantation that came to us for a second opinion. The importance of reviewing these indications reinforces the need for health care providers to spend resources and time most efficiently in the face of rising healthcare costs.

 

 

Case Report 1:
A 44-year-old woman with no significant cardiac history presented to her primary care physician and was found to be bradycardic with a heart rate of around 42 bpm. The patient was noted to have a blood pressure of 130/80 mmHg and was asymptomatic. She denied having any syncope, dizziness, fatigue and exercise intolerance. At that time, she was referred to a local cardiologist and had an electrocardiogram (ECG) done which showed a complete heart block and a QRS of 0.09 seconds (Figure 1).

Figure1-ECG

Figure 1. Patient’s ECG showing complete heart block

The patient then presented to our clinic for a second opinion. The patient underwent a Holter monitor which revealed persistence of complete atrioventricular (AV) block, and a subsequent stress test which showed adequate chronotropic competence (a rise in heart rate to >85% age adjusted maximum heart rate during stress) (Figure 2), precluding the need for a permanent pacemaker implantation.

The patient has been asymptomatic for over three years, while continuing to work, ride a twowheeler to work and walk 5 km daily. This was possibly a congenital heart block detected later in life.

Figure2-ECG

Figure 2. Patient’s Stress test ECG showing chronotropic competence

Case Report 2:
An 82-year-old male with a history of coronary artery disease (CAD) presented to his primary doctors as he required a health insurance ECG for traveling abroad. The ECG that was done was found to have a 2nd degree type II AV block, 2:1 (Figure 3). The patient was not having any symptoms of angina, fatigue, syncope or palpitations. The patient was then referred to a cardiologist who recommended placement of a permanent pacemaker. This patient came to our clinic for a second opinion.

The patient underwent a Holter monitor and was found to have a single episode of a three second pause (at 1 a.m.) with an average heart rate of 59 bpm. Subsequently he underwent a stress test during which he achieved 105% of maximum predicted heart rate without provocation of symptoms or ECG changes, precluding the need for a pacemaker implantation. The patient has been active and asymptomatic for over 9 months. The etiology is likely age-related sick sinus syndrome 

Figure3-ECG

Figure 3. Patient’s ECG showing 2nd degree heart block

Discussion:

According to the 11 world survey of pacemaker implantation, the most common initial indication for implantation includes sick sinus syndrome and high degree AV blocks, with the former being slightly more common. Approximately 20,000 new implants were reported in India, a significant increase from 2005 data showing new implants numbering [1] 12,000. We have previously reported decreased ability for poor patients to have access to [2,3] pacemakers and defibrillators.

The Class I recommendation for indications of pacemaker implantation in 3rd degree AV blocks, as per the American College of Cardiology and American Heart Association, ACA/AHA, are summarized here:

  • Any 3rd Degree block with symptoms merits pacer implantation (including those who must take medications for other medical conditions that can cause bradycardia)
  • Asymptomatic 3rd degree AV blocks which are thought to be causing ventricular arrhythmias 3rd degree blocks and episodes of asystole equal to or greater than 3 seconds
  • Escape rhythms <40 bpm
  • Patients with neuromuscular diseases
  • Post cardiac surgery or AV ablation that result in a block
  • Patients with cardiomegaly or left ventricular (LV) dysfunction
  • If the block is below the AV node (in the His [4] system or distally)

It is reasonable then for the referring doctor to be able to evaluate the patient for these indications and obtain a second opinion. In general, a patient with no other complicating cardiac issues, as in the cases presented here, who are found to have 2nd degree and 3rd degree heart blocks with a heart rate above 40 bpm and chronotropic competence, can be managed with follow up by using Class I recommendations. 

Guidelines from the ACA/AHA for 2nd degree heart blocks for indications for pacemaker implantation include:

  • Any bradycardia patient with symptomatic 2nd degree block (including those who take a necessary medication that can cause bradycardia)
  • Those with episodes of asystole >3 seconds, a rate <40 bpm or an escape rhythm below the AV node
  • After cardiac surgery or AV ablation with no expectation of improvement
  • In those with neuromuscular disorders
  • AV block that is induced during exercise

A 2nd degree type II AV block with a widened QRS (> 0.12 seconds) or chronic bifascicular block is an indication for a pacemaker, even in [5] the absence of symptoms. these additional ECG abnormalities are associated with worsening of the block to 3rd degree and often with heart failure, and so there would likely be associated pathology to consider. If the patient was monitored long term for 2nd & 3rd degree blocks and was found to have atrial fibrillation and a pause greater than 5 seconds, a pacemaker is indicated.

Considering our second patient with a 2nd degree heart block with no other ECG abnormalities or heart failure, using class I recommendations, it is reasonable to follow up with this patient instead of pursuing a pacemaker implantation.

By understanding these guidelines, a referring physician can feel confident in managing a newly discovered 2nd or 3rd degree heart block in the asymptomatic and heart healthy patient.

Article By:

Ana Karina Jaques, MD, FESC
Consultant Cardiologist,
Goa America Heart Foundation
Panaji, Goa.

Corey Meador
Medical Student
Drexel University College of Medicine

D.A.N. Neville Mascarenhas, MD, FACC
Clinical Professor of Medicine
Drexel University College of Medicine
Philadelphia, PA, USA
Honorary Cardiologist Founder Trustee
Goa America Heart Foundation
Panaji, Goa.
Email: danmasc@rcn.com

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