Septal Infarction and Complete Heart Block following PCI of the LAD (full title below)

From the ^*SUNY Buffalo Cardiology Fellowship, Buffalo, New York, and ^§Buffalo VA Medical Center, Buffalo, New York. The authors report no conflicts of interest regarding the content herein. Manuscript submitted November 17, provisional acceptance given December 2, 2008 and final version accepted December 4, 2008. Address for correspondence: Dmitriy Kireyev, MD, Cardiology Department, Buffalo VA Medical Center, 3495 Bailey Avenue, Buffalo, NY 14215. E-mail: dimonk5@yahoo.com

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ABSTRACT: Occlusion of septal perforator arteries may lead to angina, myocardial infarction, arrhythmias, atrio-ventricular (AV) block and heart failure. Percutaneous coronary intervention (PCI) on septal arteries has been performed to alleviate anginal symptoms. We describe the case of a patient who underwent routine PCI of his proximal left anterior descending (LAD) artery complicated by septal artery occlusion, septal infarction and the development of complete heart block. The patient underwent successful balloon angioplasty of the first septal perforator which led to partial recovery of AV conduction and hemodynamic stabilization.

J INVASIVE CARDIOL 2009;21:E48–E50

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Percutaneous coronary interventions (PCIs) have become increasingly common over the past decade, with more than 660,000 performed in United States in 2004.¹ We describe a case report where a patient with a proximal left anterior descending (LAD) artery lesion who received an elective bare-metal stent developed compromise of a septal perforator artery (SPA) within hours of the procedure. Such complications have been described in the literature, including septal infarction and conduction disturbance.^2,3 Although infrequently performed, angioplasty of the SPA has been used to successfully treat SPA stenosis.^4–6 Our case highlights the importance of post-procedural monitoring and consideration of intervention on compromised SPA in cases complicated by conduction system disturbances. Case Report. A 59-year-old male with a history of hypertension, diabetes mellitus and recent-onset angina was referred for PCI of the LAD after he was found to have a proximal 95% lesion on diagnostic coronary angiography (Figure 1A). An electrocardiogram (ECG) prior to procedure showed sinus bradycardia with first degree atrio-ventricular (AV) block. The patient underwent successful placement of a 4.5 mm x 20 mm Liberté™ stent (Boston Scientific Corp., Natick, Massachusetts) which was postdilated with a 4.5 mm balloon (Figure 1B). Intravascular ultrasound (IVUS) was performed and showed good apposition of the stent except for the proximal part which was subsequently dilated with a 5 mm balloon. Repeat IVUS showed improvement in stent apposition. The first SPA, across which the stent was placed, was noted to have a 90% stenosis post procedure. The patient appeared to tolerate the procedure well with no immediate complications, and he was subsequently admitted to the telemetry unit for overnight observation. Approximately 10 hours post procedure, the patient developed chest discomfort associated with nausea, vomiting and hypotension. The ECG showed sinus bradycardia at 45 bpm with first-degree AV block and new onset right bundle branch block (RBBB). An echocardiogram performed at the bedside showed normal left ventricular (LV) contractility and wall motion, with no evidence of pericardial effusion. The patient was then taken to the catheterization laboratory for diagnostic coronary angiography to evaluate the patency of the LAD stent and to exclude other acute coronary pathologies. The LAD stent was found to be patent and the other coronary arteries demonstrated no change from the earlier study. The first SPA remained 90% stenosed. The patient’s blood pressure and chest discomfort improved, and he was transferred back to the telemetry unit for continued monitoring overnight. The following morning (18 hours post procedure), the patient became severely bradycardic on telemetry and was found unresponsive. His rhythm strips from telemetry initially showed sinus rhythm with third-degree AV block and a junctional escape of approximately 50 bpm. He quickly became severely bradycardic as he lost his junctional escape and deteriorated to a ventricular escape of only 10 bpm. The patient was given intravenous (IV) atropine and epinephrine after which he developed atrial flutter with variable AV conduction and a ventricular rate of about 50–60 bpm. This was, however, punctuated by periods of high-degree AV block with a much slower ventricular rate after metabolism of the drugs. His Troponin I level, which was at 1.68 ng/ml prior to the procedure, rose to 34.36 ng/ml that morning. The patient was emergently taken back to the catheterization laboratory where a 5 Fr temporary transvenous pacemaker was inserted into the right ventricle. Coronary angiography showed patency of the stented LAD region, but complete occlusion of the previously affected first SPA (Figure 2A). The occluded vessel was successfully recannulated with a ChoICE® PT extra-support guidewire (Boston Scientific) advanced through the previously placed LAD stent (Figure 2B). Balloon angioplasty was performed using 2 mm x 15 mm and 2.5 mm x 12 mm Maverick® balloons (Boston Scientific). A kissing-balloon technique using a 4.5 mm x 12 mm Quantum™ balloon (Boston Scientific) was subsequently employed to protect the LAD stent (Figure 2C). Thrombolysis in myocardial infarction (TIMI) flow improved from 0 to 3 (Figure 2D). A balloon pump was placed at the end of the procedure, as the patient was hypotensive. The patient’s native rhythm several hours post procedure was sinus with complete heart block and a ventricular escape of less than 10 bpm. On day 1 post angioplasty of the SPA, the patient had improved hemodynamically and the intra-aortic balloon pump was removed. His conduction disturbance had partially resolved on day 2, as he was in sinus rhythm with first-degree AV block and RBBB with a rate of 70–80 bpm. Because of the persistence of the RBBB and the absence of significant ventricular escape rhythm during complete heart block, the patient underwent permanent pacemaker implantation on day 4. He experienced no further chest pain or other complications and was discharged on day 5. Discussion. Occlusion of SPAs can lead to anginal symptoms, infarction, arrhythmias, conduction disturbances and congestive heart failure.^2,3,7,8 PCI to the LAD is frequently performed across SPAs. This increases the risk of their occlusion via plaque shift or debris dislodgement during stent deployment. The anterior SPA arises from the LAD at a right angle to the epicardial surface and penetrates the interventricular septum in a caudal course, which makes intervention of this artery challenging.⁹ In our case, the patient had new-onset complete heart block and infarction of the interventricular septum secondary to occlusion of the first SPA. This was preceded by development of RBBB, which may have been a warning sign that blood flow to the interventricular septum and conduction system had become compromised. Even though complete heart block associated with anterior myocardial infarction is usually considered to be irreversible due to permanent damage to the conduction system, we decided to attempt intervention on the patient’s occluded SPA, given the recent onset of his symptoms and the acute rise in Troponin I. Restoration of blood flow did not result in immediate reversal of the complete heart block. However, we observed a return of AV conduction via the left bundle of His within 48 hours. Furthermore, the patient was initially hemodynamically unstable, but by 24 hours post intervention, he had stabilized. More proactive intervention of the SPA at the time the patient developed RBBB could potentially have limited the eventual extent of septal infarction and conduction system disturbance. Topaz et al described a series of 11 patients who underwent angioplasty of the SPA.¹⁰ All 11 patients had a successful procedure, with only 1 needing repeat percutaneous transluminal coronary angioplasty (PTCA) after acute closure of the originally dilated artery. Four patients required repeat cardiac catheterization due to recurrence of chest discomfort at a mean timing of 5 months. Vemuri et al described a series of 21 patients with long-term follow up (20 ± 9 months) in which the procedure was successful in 20/21 patients.¹¹ Septal artery angioplasty was not associated with aortic dissection, myocardial infarction or death in either study, and there was no need for repeat PTCA during the follow-up period in the Vemuri et al series. Thus, one may conclude that angioplasty of SPAs is a relatively safe procedure that produces good overall outcomes. Although SPA stenting has been described previously,^4,12 it is performed infrequently. The relative paucity of data on SPA stenting and lack of follow-up information makes it hard to conclude that there is any benefit of this technique over balloon angioplasty. We present an interesting case of intervention on a SPA. Performing interventions on SPAs may be considered in some cases of conduction disturbance associated with acute SPA occlusion in patients with appropriate vessel size. Reversal of complete heart block may prevent the need for pacemaker placement, and restoration of coronary flow may improve the patient’s hemodynamic status. A case control study is needed to evaluate the hypothesis that an interventional approach to restoring flow in the setting of SPA occlusion can lead to better patient outcomes.

References

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