Successful coronary angioplasty of a spontaneous occlusion of the conus artery causing a ST-segment elevation myocardial infarction and electrical storm

Abstract

Background

Conus artery occlusion is a rare life-threatening event, typically secondary to iatrogenic etiology, and is treated mainly with conservative therapy and/or balloon angioplasty without stenting. However, treatment remains challenging.

Case presentation

We report the case of a 60-year-old man with a known history of coronary artery disease presenting with multiple internal defibrillator cardioversions due to an electrical storm (recurrent ventricular fibrillation). The coronary angiography showed an acute occlusion of the conus artery arising from the proximal segment of the right coronary artery, treated by percutaneous transluminal coronary angioplasty with stenting (drug-eluting stent) without any serious complications.

Conclusions

To our knowledge, this is the first case in the literature where a non-iatrogenic occlusion of the conus artery causing a ST-segment elevation myocardial infarction and electrical storm was treated with percutaneous coronary intervention with drug-eluting stenting.

Graphical abstract

Background

The conus artery is the first branch of the right coronary that normally revascularizes the right ventricular outflow tract (Meng et al. 2022), and it may serve as a source of collateral for other epicardial coronary arteries in the event of their occlusion (Aggarwal 2019). However, it may arise directly from the antero-right sinus of the aorta in 10–50% of cases (Gentile et al. 2021). Conus artery occlusion is very rare, occurs due to an iatrogenic etiology in most cases, and leads to ventricular arrhythmias (Sharma and George 2020).

In the present paper, we report the first documented case of spontaneous occlusion of a conus artery arising from the proximal segment of the right coronary artery, causing cardiac arrest with an electrical storm, and successfully treated by angioplasty with the placement of a drug-eluting stent.

Case presentation

A case of a 60-year-old man (body weight of 100 kg) is presented. He is known for hypertension, active smoking, and heart failure with a reduced left ventricular ejection fraction of 30% requiring cardiac resynchronization therapy with defibrillator implantation (CRT-D)—Saint Jude Medical as a primary prevention and coronary artery disease (a chronic occlusion of the ostium of a small-diameter obtuse marginal artery requiring medical treatment and percutaneous angioplasty of the right coronary artery done three years ago). He was treated with 100 mg of Aspirin, 2.5 mg of Bisoprolol and 40 mg of Atorvastatine.

He presented to the emergency department of Bastia Hospital Center (France) after receiving multiple internal electric shocks delivered by his CRT-D over a 15-min period, concomitant with persistent oppressive chest pain. Vital parameters were within the normal range, as was the physical examination. The initial electrocardiogram (ECG) showed a ventricular-paced rhythm, like the patient’s baseline ECG (Fig. 1).

Fig. 1

The patient’s ECG. Panel A initial ECG after receiving multiple internal electric shocks. Panel B patient’s baseline ECG

The patient was treated with 300 mg of intravenous Amiodarone (Cordarone, Sanofi Winthrop Industry, France) infused over 30 min. An interrogation of his CRT-D showed 13 episodes of ventricular fibrillation, each terminated by an internal electric shock (Figs. 2, 3).

Fig. 2

Ventricular fibrillation (2 episodes shown) detected during CRT-D interrogation

Fig. 3

Ventricular fibrillation regulated with a 36-J internal electric shock

Since the patient had persistent chest pain, an emergency coronary angiogram was then performed, showing a known chronic occlusion of the second marginal, an absence of intrastent restenosis of the right coronary artery, and an acute occlusion of the middle portion of the conus artery arising from the proximal segment of the right coronary artery persisting despite injection of 1 mg intracoronary of Isosorbide Dinitrate (Risordan, Sanofi, France) (Fig. 4). The patient was treated with 250 mg intravenous Acetylsalicylic Acid (Aspégic, Opella Healthcare France SAS, France), 180 mg orodispersible Ticagrelor (Brilique; AstraZeneca, London, United Kingdom), and 50 mg subcutaneous + 50 mg intravenous Enoxaparin (Lovenox, Sanofi Winthrop Industry, France).

Fig. 4

Coronarography. Angiography of the left coronary artery (panels A and B) showing the chronic occlusion of the second marginal artery (arrow of panel A), and of the right coronary artery (panel C) showing the acute occlusion of the conus artery (arrow of panel C)

A decision was taken to recanalize the occluded conus artery (culprit artery) because of the persisting chest pain and occluded conus artery despite intracoronary vasodilators. The ostium of the right coronary artery was engaged with 6 French Amplatz® Left 0.75 (AL 0.75, 100 cm) Launcher guiding catheter (Medtronic Inc., Minneapolis, MN, USA). A 0.014″ J-tipped Sion® Blue guidewire (Asahi Intecc Co. Ltd.) was inserted distally into the right coronary artery to improve support for the guiding catheter. The conus artery was recanalized with another 014″ J-tipped Sion® Blue guidewire (Asahi Intecc Co. Ltd.), with recovery of a Thrombolysis In Myocardial Infarction (TIMI) Flow II.

A semi-compliant percutaneous coronary balloon angioplasty Ryurei® 2.0 × 15 mm (Terumo, Tokyo, Japan) was inflated at a maximum pressure of 12 atmospheres for a total duration of 15 s at the level of the occlusion, with a slow flow in the conus artery. Due to the suboptimal result in the conus artery following balloon angioplasty, the procedure was completed with the placement of a drug-eluted stent, Orsiro® Mission 2.25 × 18 mm (Biotronik, Berlin, Germany), inflated at 14 atmospheres for a total duration of 20 s in the middle segment of the conus artery. Final angiographic control showed a TIMI Flow III in the conus artery (Fig. 5) with complete recovery of the chest pain. No cardiac arrhythmias were noted during the procedure, during which the patient remained hemodynamically stable.

Fig. 5

Percutaneous coronary intervention. Successful recanalization of the conus artery with an 0.014″ J-tipped Sion® Blue angioplasty guidewire with a TIMI Flow II, followed by stenting using a drug-eluting stent inflation (arrow), with a good result in the conus artery

The patient was monitored in the cardiac intensive care unit. His post-intervention ECG remained unchanged. His blood analysis done prior to coronary angiography showed a slightly increased troponin level at 61 pg/ml (normal range < 34 pg/ml) and normal creatine phosphokinases (CPK) at 199 IU/l (normal range 30–200 IU/l). The rest of the workup was unremarkable. The blood analysis performed 24 h after the procedure showed a troponin peak above 50,000 pg/ml and CPK at 1433 IU/l. Cardiac enzymes subsequently decreased. A cardiac ultrasound showed a known reduced left ventricular ejection fraction (32% calculated using the Simpson method) without pericardial effusion or mechanical complications. The patient’s clinical condition was stable during the hospital stay, with no recurrence of chest pain or arrhythmias.

He was discharged from the hospital four days later without any complications. During follow-up at one and six months, the patient was asymptomatic, and CRT-D interrogation showed no recurrence of ventricular arrhythmias. A myocardial perfusion scan done two months after hospital discharge showed no residual ischemia.

Discussion

In the literature, the main causes for conus artery occlusion are secondary to surgical repair of the mitral valve (Hernández Hernández et al. 2011), selective intubation of the conus artery and iodinated contrast media injection during right coronary artery angiography (Sharma and George 2020), and occlusion of the conus artery ostium arising from the proximal segment of the right coronary artery during stent placement on this segment (Eichhöfer and Curzen 2005).

A spontaneous conus artery occlusion is extremely rare in the literature. It was reported during ST-segment elevation myocardial infarction by Umemura et al. (2012) where the occlusion was recanalized only by passing an angioplasty guidewire into the artery, by Kuzemczak et al. (2020) where a guidewire was inserted into the occlusion without restoring normal blood flow, and by Lyle et al. (2016) where the occlusion was not recanalized since it was identified retrospectively due to difficulties in engaging the right coronary ostium. To our knowledge, no case of angioplasty with stent placement at the level of the conus artery has been reported in the literature to date.

Our patient presented initially after receiving several electric shocks from his CRT-D. The CRT-D interrogation showed 13 episodes of ventricular fibrillations, each one treated by an appropriate internal electric shock. This is considered an electrical storm, defined by the presence of at least three sustained episodes of ventricular arrhythmias, each requiring termination by an intervention, or at least three appropriate shocks from an implantable defibrillator over a single twenty-four-hour period (Dyer et al. 2020). This presentation is classical in conus artery occlusions (Sharma and George 2020). The presence of an implantable defibrillator was life-saving for our patient.

Besides angina, the occlusion of the conus artery is generally reproduced on the EKG by an ST-segment elevation in the precordial leads from V1 to V3 (Sharma and George 2020 ; Matthews and Oesterle 1989). In our case, the presence of a ventricular-paced rhythm on the EKG prevented us from detecting the electrical changes of myocardial infarction due to acute occlusion of the conus artery. ST-segment elevation of 2 mm in precordial leads V1–V3 on a ventricular-paced rhythm with a left branch block morphology is not sufficient to confirm ST-segment elevation myocardial infarction. Furthermore, the conus infarction was clearly responsible for the ventricular fibrillation episodes noted on the CRT-D interrogation but was not responsible for the electrical changes noted on the initial ECG in the emergency department since it was comparable to the patient’s baseline ECG.

In our case, we have preferred to do conus artery angioplasty with the placement of a drug-eluting stent given the suboptimal result after recanalization of the conus artery by the angioplasty guidewire (TIMI Flow II). The patient’s hemodynamic stability and the absence of arrhythmias during the procedure enabled us to treat the conus artery occlusion like any other coronary branch occlusion with an excellent result.

Conclusions

Myocardial infarction due to acute occlusion of the conus artery is a dramatic, life-threatening event that generally presents with ventricular arrhythmias. Without immediate intervention, death is imminent. This case report suggests that recanalization of acute conus artery occlusion followed by percutaneous coronary angioplasty with placement of a drug-eluting stent is a safe procedure that should be performed as soon as possible to avoid life-threatening arrhythmias, even if this artery perfuses a minimal area of myocardium. Close monitoring of the cardiac rhythm during the procedure remains essential.