Complete Heart Block in Late Presentation of Inferior STEMI Successfully Treated with Percutaneous Coronary Intervention

ABSTRACT: A 55-year-old female presented with 4-day history of fatigue and exertional shortness of breath. A late presentation inferior ST elevation myocardial infarction (STEMI) was diagnosed based on ST elevation in the inferior leads of electrocardiography and elevated cardiac troponin T (TnT). She developed complete heart block 1 day after admission to the hospital and remained hemodynamically stable. She was taken to the catheterization laboratory for a temporary pacing wire insertion. Coronary angiogram at the same time showed an occluded right coronary artery at the mid-section. The lesion was successfully opened. Within 24 hours, the patient's heart rhythm returned to sinus with first-degree atrioventricular block (AVB), thus avoiding the need for a permanent pacemaker. Current guidelines recommend medical management for late presentation hemodynamically stable STEMI of more than 72 H onset. Current ACC/AHA/HRS Pacemaker Guidelines recommend reperfusion strategy for acute presentation inferior STEMI associated with AVB. However, no clear strategy exists in the case of late presentation inferior STEMI with advanced AVB. Our case report suggests that late coronary intervention could be a management strategy in such a scenario in order to avoid a permanent pacemaker.

J INVASIVE CARDIOL 2011;23:E219–E221

__________________________________

Case Report. A 55-year-old European female presented to our emergency department with 4-day history of fatigue, exertional shortness of breath, and dizziness. She denied any history of chest pain. She was a current 30 pack-year smoker with otherwise no significant past medical history or cardiac risk factors. Examination was unremarkable except for a bradycardia at 39 bpm. ECG showed a 3 to 1 second-degree AVB with significant ST elevation in the inferior leads and reciprocal depression in the lateral leads (Figure 1). TnT was 3.26 µg/L (0–0.03 µg/L). A diagnosis of late presentation inferior STEMI with heart block was made. She was relatively asymptomatic and was admitted into the coronary care unit and managed conservatively with close observation via telemetry. Approximately 12 hours following presentation, while remaining asymptomatic at rest, she developed complete heart block (CHB). She remained hemodynamically stable and an urgent temporary pacing wire was inserted (Figures 2A and 2B). Diagnostic coronary angiogram revealed minor left coronary artery disease (CAD) with an occluded dominant right coronary artery (RCA) from the mid-section (Figure 3). Due to presence of CHB, we elected to open the lesion. The occlusion was successfully crossed with a 0.014" Rinato (Asahi Intecc, Aichi, Japan) wire without much difficulty and stented with a Xience V (Abbott Vascular) 2.75 x 28mm, overlapped distally by Xience V (Abbott) 2.5 x 15mm stents (Figure 4).

Approximately 8 hours following coronary intervention to the RCA, the patient went into a 2 to 1 second-degree AVB. By the next day, she was back in a sinus rhythm with first-degree AVB (Figure 2C). Her PR-interval continued to improve during her last 48 hours in the hospital. On discharge, her PR-interval was 220 milliseconds and her inferior ST-elevation had nearly resolved (Figure 5). The three-month follow-up ECG showed normal PR interval and an incomplete right bundle branch block pattern. Q waves were present in the inferior leads consistent with the recent inferior MI.

Discussion. The AV node is supplied from the posterior descending artery or posterior interventricular artery, a branch of the RCA in right-dominant individuals. Inferior myocardial infarction (MI) complicated by AVB occurs in approximately 6% to 13% of patients and is associated with poorer prognosis.^1-3 Patients with significant AVB associated with acute inferior STEMI are expected to improve with primary angioplasty, thus, permanent pacemaker is often not required as described in the ACC/AHA/HRS Pacemaker Guidelines.⁴ In our case, however, the optimal management of CHB in the context of a stable patient with late presentation inferior STEMI (> 72 H) has not been well described in the literature. The Occluded Artery Trial (OAT) suggested that there was no difference in hard clinical endpoints (mortality, reinfarction, class IV heart failure) between the medically managed group and the intervention group for persistent total occlusion of the infarct-related coronary artery.⁵ Of note, CHB was not addressed in this trial. European Society of Cardiology (ESC 2007) guidelines for cardiac pacing and cardiac resynchronization therapy suggested that significant AVB associated with inferior STEMI is often expected to improve within 7 days and a pacemaker is recommended in patients with persistent advanced second-degree heart block or CHB 14 days after the onset of inferior STEMI.⁶

Ramamurthy et al described a patient who had chest pain associated with syncope and diagnosed with a late inferior STEMI and persistent CHB of greater than 10 days. After successful percutaneous coronary intervention (PCI) to the blocked RCA, this patient returned to sinus rhythm.7 By contrast, our patient had no history of chest pain, thus, medical management was initiated on admission as per the OAT trial in the case of a late presentation STEMI. The presence of significant bradycardia with 3:1 AVB on admission was a concern. Furthermore, the presence of dynamic conduction changes evident on ECG during the course of 24 H of observation suggested a possible reversibility of the culprit coronary lesion. The patient was therefore considered for coronary intervention, despite the present guidelines not clearly recommending reperfusion strategies for MI-related conduction abnormalities. The successful outcome (quick resolution of CHB and avoidance of permanent pacemaker insertion) in our case suggests that coronary intervention may be a valid management strategy in late presentation inferior STEMI with associated high-grade AVB or CHB, even in the absence of clinical chest pain.

References

1. Clemmensen P, Bates ER, Califf RM, et al. Complete atrioventricular block complicating inferior wall acute myocardial infarction treated with reperfusion therapy. TAMI Study Group. Am J Cardiol 1991;67:225–230.
2. Berger PB, Ruocco NA Jr, Ryan TJ, et al. Incidence and prognostic implications of heart block complicating inferior myocardial infarction treated with thrombolytic therapy: Results from TIMI II. J Am Coll Cardiol 1992;20(3):533–540.
3. Harpaz D, Behar S, Gottlieb S, et al. Complete atrioventricular block complicating acute myocardial infarction in the thrombolytic era. SPRINT Study Group and the Israeli Thrombolytic Survey Group. Secondary Prevention Reinfarction Israeli Nifedipine Trial. J Am Coll Cardiol 1999;34(6):1721–1728.
4. Epstein AE, DiMarco JP, Ellenbogen KA, et al. ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities: A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the ACC/AHA/NASPE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices) developed in collaboration with the American Association for Thoracic Surgery and Society of Thoracic Surgeons. J Am Coll Cardiol 2008;51(21):e1–62.
5. Hochman JS, Lamas GA, Buller CE, et al. Coronary intervention for persistent occlusion after myocardial infarction. N Engl J Med 2006;355(23):2395–2407.
6. Vardas PE, Auricchio A, Blanc JJ, et al. Guidelines for cardiac pacing and cardiac resynchronization therapy: The Task Force for Cardiac Pacing and Cardiac Resynchronization Therapy of the European Society of Cardiology. Developed in collaboration with the European Heart Rhythm Association. Eur Heart J 2007;28(18):2256–2295.
7. Ramamurthy S, Anandaraja S, Matthew N. Percutaneous coronary intervention for persistent complete heart block complicating inferior myocardial infarction. J Invasive Cardiol 2007;19(12):E372–E374.

__________________________________

From the Department of Cardiology, Waikato Hospital, Hamilton, New Zealand.
Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. No authors reported conflicts regarding the content herein.
Manuscript submitted January 24, 2011 and accepted February 7, 2011.
Address for correspondence: Dr. Sanjeevan Pasupati, FRACP, Department of Cardiology, Waikato Hospital, Hamilton, Pembroke & Selwyn Sts, Hamilton 3240, New Zealand. Email: drspasupati@gmail.com