Temporary pacemaker for acute Lyme carditis demonstrates complete reversibility of severe heart block. This landmark case — the first to capture day-by-day electrocardiographic progression — shows high-degree AV block evolving to third-degree complete block, then resolving to normal sinus rhythm within two weeks. The temporary pacemaker was removed on Day 6, proving young patients don’t need permanent devices when Lyme carditis is recognized and treated appropriately.

Sudden Syncope Without Warning

The patient presented with a syncopal episode with no prodrome, shortness of breath and weakness, according to the case study, entitled Electrocardiographic progression of acute Lyme disease.

“Syncope with no prodrome” means he fainted without warning. No lightheadedness beforehand. No gradual onset. One moment conscious, next moment unconscious on the floor. This pattern indicates severe cardiac pathology — his heart rate had dropped so low that brain perfusion ceased within seconds.

“Three weeks prior to the presentation, he had experienced an ‘insect bite’ on his calf after being outside. A week later, he developed chills, sweats, myalgia, back pain, headache and fatigue,” according to Fuster and colleagues, from Kingston General Hospital, Queen’s University.

The timeline is classic: insect bite, one week of feeling fine, then systemic symptoms appearing in the second week. By week three, cardiac involvement had progressed to life-threatening complete heart block.

Diagnosis and Immediate Intervention

Lyme carditis was diagnosed based on the history, a pulse rate of 38 bpm, a high degree AV block, and the absence of ischemia. A temporary transvenous pacemaker was placed through the jugular vein, and the man was admitted to the cardiac unit for monitoring and treatment. Intravenous ceftriaxone was prescribed.

The diagnosis relied on clinical judgment: young patient, recent outdoor exposure, systemic symptoms, severe bradycardia (38 bpm), high-degree heart block on EKG, and normal coronary arteries (no ischemia). This constellation pointed to Lyme carditis, not primary cardiac disease.

The temporary transvenous pacemaker provided immediate cardiac support. A wire was threaded through the jugular vein into the right ventricle, delivering electrical impulses to maintain safe heart rate while antibiotics worked to resolve the infection.

First Case to Capture Daily EKG Evolution

The Lyme carditis resolved without the need for a permanent pacemaker. The EKG progressed from a high degree AV block that rapidly evolved into 3rd degree AV block with a junctional escape rhythm to 2:1 AV block with a narrow conducted QRS by Day 5.

This daily documentation is unprecedented. Previous case reports described initial presentation and final outcome, but this is the first to capture the day-by-day electrocardiographic changes as Lyme carditis resolved with treatment.

EKG Progression Timeline:

• Day 1: High-degree AV block, pulse 38 bpm
• Days 2-3: Progressed to third-degree (complete) AV block with junctional escape rhythm
• Day 5: Improved to 2:1 AV block with narrow conducted QRS
• Day 6: Temporary pacemaker removed
• Week 2: Normal sinus rhythm restored

Notice the pattern: initial worsening (high-degree to complete block), then progressive improvement once antibiotics took effect.

Temporary Pacemaker Removed Day 6

The temporary pacemaker was removed on Day 6. By the second week, the EKG had returned to normal sinus rhythm. The man was discharged and instructed to complete 4 weeks of antibiotics.

Six days of temporary pacing was sufficient. Once his intrinsic heart rate recovered and AV conduction improved, the pacemaker could be safely removed. He walked out of the hospital with normal cardiac function and no permanent device.

“This is the first case in the literature that has captured the electrocardiographic evolution of Lyme carditis, day by day until complete resolution,” states Fuster and colleagues.

Most Patients Don’t Remember Tick Bite

According to Fuster, “Most patients presenting with Lyme carditis and new onset arrhythmia do not remember when they have been bitten or they do not have a clear history of tick bite, therefore it is a reasonable decision to investigate those patients for suspicious Lyme disease especially in high-risk areas or in patients with pathognomonic symptoms like erythema migrans (characteristic migrating rash).”

This statement validates patients who are dismissed because they don’t remember a tick bite. Most Lyme carditis patients have no tick bite memory. The absence of remembered tick exposure should not prevent Lyme testing when clinical presentation is suspicious.

In fact, “only 40% of patients with Lyme carditis report having erythema migrans rash, as compared with 70%–80% of patients overall.”

Even the EM rash — often called the “hallmark” of Lyme disease — is absent in 60% of Lyme carditis cases. Lack of rash doesn’t rule out Lyme disease.

Who Needs Hospitalization?

The authors recommend hospitalization, because a temporary pacemaker may be required. “Hospitalization is recommended for patients with 2nd or 3rd degree AV block, and for patients with 1st degree AV block and a PR interval > 300 ms.”

These aren’t arbitrary cutoffs. Second and third-degree blocks indicate significant conduction failure requiring continuous monitoring. Even first-degree block becomes concerning when the PR interval exceeds 300 milliseconds (normal is less than 200 ms) — this extreme prolongation can rapidly progress to higher-degree block.

Heart block can progress within hours, so hospitalization with telemetry monitoring is essential for patient safety.

CDC Observations on Lyme Carditis

Fuster and colleagues point out several observations and recommendations made by the Centers for Disease Control and Prevention (CDC):

1. Males are disproportionately affected by Lyme carditis.

Males represent about 90% of Lyme carditis cases. The reason isn’t fully understood but may relate to outdoor exposure patterns, delayed healthcare-seeking behavior, or hormonal factors affecting immune response.

2. Lyme disease patients ages 15-45 develop Lyme carditis more frequently.

Young adults and middle-aged individuals are at highest risk. This age distribution makes misdiagnosis particularly tragic — these patients have decades of life ahead and don’t need permanent pacemakers for reversible infections.

3. Only 40% of patients with Lyme carditis report having erythema migrans rash, as compared with 70%-80% of patients overall.

Cardiac Lyme patients are even less likely to have rashes than general Lyme patients. Don’t let absence of rash prevent Lyme testing when heart block is unexplained.

4. Patients with suspected Lyme disease should be evaluated for cardiac symptoms, including palpitations, chest pain, lightheadedness, fainting, and shortness of breath.

These symptoms indicate possible cardiac involvement. Any Lyme disease patient experiencing these should have EKG evaluation.

5. ECG is mandatory if Lyme carditis is suspected.

EKG should be obtained for any patient with possible Lyme disease who has cardiac symptoms. And conversely, any patient with unexplained heart block should be asked about Lyme disease exposure.

6. Ask patients with unexplained heart block about possible exposure to infected ticks.

Travel history, outdoor activities, geographic location, and seasonal timing all provide clues. Even without remembered tick bite, exposure history helps establish Lyme disease as likely diagnosis.

Why This Case Matters

This case demonstrates the importance of investigating patients with heart block for Lyme disease, given that carditis can be a complication of the disease. It occurs when the Lyme spirochete invade the heart at different levels. The most common clinical manifestation of Lyme carditis is AV block, which can vary between 1st, 2nd and 3rd degree block.

Progression to 3rd degree AV block can be rapid and fatal if left untreated.

This patient’s case demonstrates all the key principles:

• ✅ Young male in high-risk age group
• ✅ No remembered tick bite (validates patients without tick history)
• ✅ Rapid progression to life-threatening complete block
• ✅ Temporary pacing provided bridge during treatment
• ✅ Complete resolution without permanent pacemaker
• ✅ Day-by-day documentation proves reversibility

Clinical Perspective

The day-by-day EKG documentation in this case is invaluable. It shows that Lyme carditis doesn’t follow a smooth linear improvement. Initially, the patient worsened (high-degree block progressing to complete block) before improving. This initial worsening likely occurred as spirochetes died off and inflammatory response peaked.

By Day 5, the trend reversed. The block improved from complete to 2:1 (second-degree), indicating electrical conduction was recovering. By Day 6, recovery was sufficient to remove the temporary pacemaker. By week 2, normal sinus rhythm had returned.

This timeline informs clinical decision-making. When should temporary pacemakers be removed? When is it safe to discharge patients? This case provides concrete answers: pacemaker removal around Day 6, with normal rhythm by week 2.

The emphasis that most patients don’t remember tick bites is critical. I see patients regularly who are told “it can’t be Lyme disease, you didn’t have a tick bite.” But as this case and the literature demonstrate, tick bite memory is unreliable. Most Lyme carditis patients have no tick bite history.

Similarly, the 40% EM rash figure for Lyme carditis (versus 70-80% overall) means 60% of cardiac cases have no rash. Lack of rash cannot exclude Lyme disease when clinical picture is otherwise consistent.

The temporary pacemaker approach prevented permanent device placement in a young patient. Had this been misdiagnosed as primary cardiac disease, he might have received a permanent pacemaker, committing him to decades of device complications. Instead, he recovered completely with no permanent device needed.

Frequently Asked Questions

Why did the heart block worsen initially despite antibiotics?

The progression from high-degree to complete block in the first days likely represents either natural progression of untreated infection or inflammatory response as spirochetes die (Jarisch-Herxheimer reaction). Once antibiotics take effect, improvement follows. This case shows worsening through Day 3, then improvement by Day 5.

How long do temporary pacemakers stay in place for Lyme carditis?

This case required 6 days of temporary pacing. Most Lyme carditis patients need temporary devices for less than 2 weeks. Once heart block improves and intrinsic rhythm returns, the pacemaker can be removed.

Can you be discharged with a temporary pacemaker?

Some temporary pacemakers (temporary-permanent type) allow discharge, but this patient remained hospitalized until device removal. Transvenous temporary pacemakers typically require hospitalization because the external wire is a infection and dislodgement risk.

What if I don’t remember a tick bite?

Most Lyme carditis patients don’t remember tick bites. Nymphal ticks are poppy-seed sized and easily missed. The authors emphasize that lack of tick bite memory shouldn’t prevent Lyme disease investigation when clinical presentation is consistent.

Should I get an EKG if I have Lyme disease?

Yes, if you have any cardiac symptoms: palpitations, chest pain, lightheadedness, fainting, shortness of breath. The CDC states ECG is mandatory if Lyme carditis is suspected. Even without symptoms, some providers obtain baseline EKG for Lyme patients.

What does “no prodrome” syncope mean?

Syncope with no prodrome means fainting without warning — no lightheadedness, no gradual onset. This pattern suggests severe bradycardia or complete heart block causing sudden drop in cardiac output and brain perfusion. It’s more concerning than gradual faint preceded by warning symptoms.

How common is Lyme carditis without rash?

60% of Lyme carditis patients have no EM rash. The 40% rash rate in cardiac cases is even lower than the 70-80% rate in general Lyme disease. Absence of rash is common in Lyme carditis.