A Case of Hypertrophic Obstructive Cardiomyopathy Complicated by a Single Coronary Artery Treated by Transcoronary Septal Ablati

Hypertrophic obstructive cardiomyopathy (HOCM) is a disease characterized by left ventricular hypertrophy and the presence of an outflow tract gradient. Transcoronary ablation of the septal hypertrophy (TASH) by selective transcatheter septal branch injections of ethanol has been shown to substantially reduce the outflow obstruction and improve symptoms and cardiac function.^1,2 Here, we describe an extremely rare case in which a patient underwent TASH to treat HOCM that was complicated by the presence of a single coronary artery anomaly arising from the right coronary cusp. Because of anatomical abnormalities, the buddy wire technique was required to perform TASH. Furthermore, serial ECG changes associated with two septal branch ablations clearly demonstrated important changes indicating the development of conduction disturbances during the procedure. Case Presentation An 80-year-old man had been followed at an outpatient clinic since 1991 because of a history of syncope and a diagnosis of hypertrophic obstructive cardiomyopathy. Since then, he has been in good health and has been maintained on medical therapy (propranolol 120 mg t.i.d. p.o.). However, in 2003 he began to suffer severe exertional dyspnea during basic daily activities and had a presyncope attack, prompting admission to our facility. Physical examination revealed jugular venous distention, brisk carotid upstrokes and a harsh systolic murmur at the left lower sternal border. Electrocardiography on admission revealed paroxysmal atrial fibrillation at 47 b.p.m. with inverted T waves in aVL, aVF, and V3–V6 (Figure 1). Echocardiography revealed a septal wall thickness of 26 mm and a resting outflow pressure gradient of 164 mmHg after spontaneous conversion to normal sinus rhythm. Because his symptoms of heart failure were unresponsive to medical treatment, we decided to perform TASH. Coronary angiography disclosed no significant coronary artery narrowing. However, a single coronary artery anomaly was found. This single coronary artery originated from the right sinus of Valsalva, with the circumflex and left anterior descending (LAD) branches arising separately from a common trunk. The circumflex branch traveled in a retroaortic fashion to the atrioventricular groove, while the LAD branch coursed between the aorta and pulmonary trunk to the interventricle sulcus (Figure 2). This single coronary artery had two major septal branches: one originated from the LAD, and the other was from an intermediate artery between the LAD and the circumflex (Figure 2A). Procedure. Heparin (100 U/kg) was administered after a 7 French (Fr) long sheath was inserted into the patient’s right femoral artery and a 5 Fr short sheath was inserted into his left femoral artery. A 7 Fr Amplatz-type guiding catheter was placed in the orifice of the single coronary artery, and a 5 Fr multipurpose catheter was placed in the left ventricle (LV) to monitor the pressure continuously. A 5 Fr temporal pacing catheter was inserted via the right internal jugular vein and placed in the right ventricular apical region. Probationary ballooning was performed on the two septal branches (intermediate branch between the LAD and circumflex, Figure 2B; largest septal branch from the LAD, Figure 2C) under continuous monitoring of the left ventricular outflow tract (LVOT) gradient. Pressure gradient reduction by probationary ballooning was similar for both septal branches. Advancement of the over-the-wire 1.5 x 9 mm balloon catheter (Boston Scientific Scimed, Inc., Natick, Massachusetts) in the septal branch originating from intermediate branch was impossible due to severe angulation of the proximal portion. Therefore, the guiding catheter was exchanged for a Judkins R-type, and two guidewires were inserted. One was advanced in the septal branch originating from the intermediate artery and the other in the LAD to ensure guiding catheter backup (Figure 2B). In the septal branch originating from the LAD, wire crossing was difficult with both a floppy and then a hydrocoated guidewire. A floppy wire was advanced in the LAD distally, and then a hydrocoated wire was manipulated into the culprit artery. Even though the hydrocoated guidewire could advance into the septal artery, the balloon could not advance. Therefore, another floppy guidewire was advanced to the distal LAD to enable advancing of the balloon to the septal branch (Figure 2C). After balloon inflation, correct placement of the balloon catheter was verified by injection of contrast agent into the coronary artery. In addition, a small amount of dye was injected through the central lumen of the inflated balloon to determine the supply area of the septal branch. Thereafter, 1.0 ml of ethanol was slowly injected into the septal branch originating from the LAD. Ten minutes after the injection of ethanol, the balloon catheter was deflated and occlusion of the septal branch was verified. The decrease in the LVOT gradient was more than 70 mmHg (Figure 3). However, the LVOT gradient after the first ethanol injection into the septal branch remained at 40% of the baseline value. Therefore, a second ablation of the septal branch originating from the intermediate coronary artery was performed by injection of another 1.0 ml of ethanol (Figure 2D). The pressure gradient was abolished completely after the second septal ablation (Figure 3). The peak creatinine kinase release was 1,437 IU/L, but complete atrioventricular block did not occur after the procedure. Transthoracic Doppler echocardiography showed that the LVOT gradient was only 4 mmHg, and no systolic anterior movement of the mitral valve was present. The patient’s condition improved without procedural complications. During follow up, recurrence of pressure gradient did not occur, and neither light headedness nor syncope were noted thereafter. ECG changes during ablation. During the first ablation of the septal artery which arose from the anterior descending artery, the PQ interval was 0.22 sec., and first-degree atrioventricular (AV) block was present. The QRS duration was 0.12 sec. The ST segment was elevated in leads V2 and V3 (Figure 4). However, when the second ablation to the septal artery that originated from the intermediate artery was performed, the PQ interval increased to 0.30 sec. The QRS duration increased to 0.20 sec. and had a right bundle branch block morphology with left axis deviation (Figure 5), indicating the presence of bifascicular block, but not complete heart block. ST-elevation was present in leads V1–V5. The predominant ST-elevation shifted from lead V2 to leads V3, V4, and V 5. Discussion TASH for HOCM is considered to be an effective alternative treatment to surgical myectomy.³ Previous reports have confirmed that TASH decreases substantial and sustained LVOT pressure gradients and improves symptoms.^4–6 Our patient also had remarkable improvement in LVOT obstruction and improved symptoms following TASH. TASH for single coronary artery anomaly. A single coronary artery has been reported to occur in approximately 0.024–0.04% of the population.^7,8 There is only one report of a single coronary artery in the setting of nonobstructive hypertrophic cardiomyopathy.⁹ To the best of our knowledge, this is the first report describing a case of HOCM with an associated single coronary artery anomaly that underwent TASH for LVOT obstruction. The target artery is most commonly a septal perforator branch located 10–30 mm from the origin of the LAD. In a few cases, the target vessel originates from an artery other than the LAD. Faber et al. reported that most of the target vessels for TASH originate from the LAD, but 8.5% arise from other vessels.² In our case, one of the target vessels did not arise from the LAD, but from the intermediate artery. The success rate of TASH also is comparable to that of surgical myectomy.³ However, the technique used for TASH is highly dependent upon the anatomy of the coronary septal branch artery. Because our patient had a single coronary artery arising from the right coronary cusp, both wire and balloon advancements were highly complicated. In this case, the buddy wire technique was useful. This wiring technique ensured the position of the guiding catheter at the right coronary cusp during the procedure, and effectively enhanced the back up power of the guiding catheter. Presumably, the buddy wire also straightened the course of the LAD and altered the angulation between the septal branch and the LAD, making wiring of the culprit artery easy. These wiring techniques therefore lead to a successful procedure. In order to determine the target septal branch, contrast echocardiography can be used, as Lakkis et al.¹⁰ demonstrated. Even though we did not perform this procedure, contrast echocardiography might enhance the procedure assessment and make the procedure simpler. ECG changes during procedure. TASH results in several kinds of conduction disturbance including first-degree AV block, right bundle branch block and intraventricular conduction block. However, permanent first-degree block is relatively rare, with a reported incidence of only 2%.^10–12 In contrast, it has been reported that right bundle branch block occurs in 60–100% of patients after TASH.^12,13 However, complete heart block (CHB) can develop transiently in up to two-thirds of patients, or permanently in 0–25% of treated patients. The identification of patients at high risk for developing CHB is difficult due to individual variations in septal perforator branch anatomy. However, Chang et al.¹¹ recently demonstrated that multiple demographic, electrocardiographic and technical factors seem to increase the risk of CHB after TASH. They reported that the number of injected septal arteries is one of the predictors of the development of CHB, probably due to the involvement of multiple conduction pathways. In our case, the first ablation resulted in first-degree AV block and widening of the QRS complex; the second ablation resulted in the progression of conduction disturbances to PR prolongation and bifascicular block. Therefore, this case may represent a typical sequence of conduction disturbance caused by TASH of two septal arteries. Serial ECG changes caused by the two septal ablations are thought to indicate the progression of conduction disturbances in a step-by-step fashion. In conclusion, we describe a case of HOCM complicated by a single coronary artery. The patient was treated successfully by TASH. The case is especially informative, not only because of its technical aspects, but also because of the ECG changes observed during the procedure. How Would You Treat This Patient? Paul Sorajja, MD Division of Cardiovascular Diseases and Internal Medicine Mayo Clinic College of Medicine, Rochester, Minnesota The case of this 80-year-old man with obstructive hypertrophic cardiomyopathy (HCM) is provocative, and raises some technical issues when performing percutaneous septal ethanol ablation. Current septal reduction therapy in HCM comes down to a choice between surgical myectomy and septal ablation. In our practice, we prefer septal myectomy in those patients who are younger or who have concomitant disorders that warrant an open surgical procedure (e.g., intrinsic mitral valve disease, need for bypass grafting). Given the relative paucity of long-term data on the effects of septal infarction, we prefer that septal ablation not be performed on otherwise healthy young individuals, but be limited to older patients, particularly if they have a number of comorbidities (besides age) that would place them at significantly increased perioperative risk. As well-demonstrated, the unusual aspect about this case is the anomaly of a single coronary artery with the left anterior descending coursing between the great vessels. In our institution, patients with this coronary anomaly in isolation should undergo evaluation for myocardial ischemia, followed by bypass grafting or re-implantation of the left coronary artery if ischemia is present. There are some who even promote operation in the absence of ischemia given the risk of sudden death which is present in these patients. The advanced age of this patient suggests that myocardial ischemia and possible sudden death has probably not been a major problem in the past. However, the recent onset of his symptoms raises the possibility that the combined coronary anomaly coupled with the hypertrophy from the HCM may be causing myocardial ischemia. The disease manifestations of HCM and the progression of myocardial hypertrophy may occur at any age, with potential worsening of the balance between myocardial oxygen supply and demand. Notably, several recent investigations have documented the adverse effects of myocardial ischemia in adult patients with HCM, with cardiovascular event rates that exceed 3% per year. If surgery is required to address myocardial ischemia with bypassing the anomalous coronary artery, then the septal reduction therapy of choice is a concomitant myectomy. Thus, we would have addressed the possibility of the anomalous coronary artery causing myocardial ischemia with further imaging modalities prior to a decision on the method of septal reduction therapy. Also of note, in the differential diagnosis of this patient’s symptoms, one may consider the patient’s atrial fibrillation and the slow ventricular response observed during the presenting episode. Furthermore, the absence of hypertrophy on his electrocardiogram in the presence of severe hypertrophy on echocardiography raises the possibility of infiltrative disorders such as amyloidosis. If septal ablation is the procedure to be performed, there are several comments on the procedure itself. Dr. Hara is to be commended on the successful technical navigation of the septal arteries, whose tortuous course provides significant challenges and often precludes procedural success. Few reports have addressed this issue, particularly the use of buddy wiring to attain the necessary support for delivery of the over-the-wire balloon. Moreover, examining the intermediate branch for putative septal perforators is important, and may easily be overlooked in evaluating patients for ablation. Nonetheless, several comments regarding the techniques used in this patient can be made and applied in the approach to all patients undergoing this procedure. Targeting of the basal septum and the area at which there is contact of systolic anterior motion of the mitral valve is a key component of procedural success. Although probationary balloon occlusion of either septal artery gave rise to the same gradient reduction in this patient, the effects of balloon occlusion on gradient reduction differ from that due to ethanol injection. This observation is arguably due to septal collaterals, which are less effective following septal infarction. Thus, reliance on probationary balloon occlusion can be an insensitive means for deciding on the appropriate target septal artery. Notably, successful septal ablation can be achieved irrespective of the hemodynamic effects observed during balloon occlusion. In all septal ablation procedures, we perform adjunctive myocardial contrast echocardiography to ensure the target septal artery supplies the targeted area of myocardium. By direct visualization, contrast echocardiography has been shown to significantly decrease acute complications of septal ablation with less infarct size and reduced need for permanent pacemaker implantation. One may adequately visualize angiographic contrast on echocardiography to obviate the need for the additional injection of dedicated echocardiographic contrast. However, careful echocardiography should be performed to ensure the septal artery does not supply unwanted areas of myocardium (e.g., papillary muscles, free walls or apices of the left or right ventricles). In this patient, the target septal artery arising from the left anterior descending artery originates a considerable distance from the artery arising from the intermediate branch. This distance raises the potential for infarction that is either excessively apical or anterolateral following ablation of these two arteries. Of note, multiple views of arteries from the right and left anterior oblique projections are beneficial in ensuring their septal course, particularly when they arise from branches apart from the left anterior descending. In this patient, the presence of ST-segment elevation in leads V1–V5 on the postprocedural electrocardiogram suggests an extensive myocardial infarction may have occurred. Septal ablation typically results in infarction that is approximately 8% to 10% of the left ventricle, which may not be the case in this patient. Blase A. Carabello, MD Houston VA Medical Center Houston, Texas In this case of an 80-year-old man with hypertrophic cardiomyopathy (HOCM) and single coronary artery, alcohol septal ablation (ASA) was performed. Because there were two major septal arteries involved, both were treated after therapy in one left a substantial residual gradient. Indications for ASA were progressive dyspnea despite propanolol 360 mg/day and syncope. In the absence of randomized trials and in view of the heterogeneity of the condition, the therapy seems reasonable. Other attempts at medical therapy could have been tried but would have likely produced incremental improvement at best. While there is yet no proof that ASA will prolong life in such a patient, there is good expectation that symptoms will improve. One concern is the patient’s syncope. It appears that syncope in this case was attributed to hemodynamic obstruction to left ventricular outflow. While this assumption was reasonable, the obvious alternative explanation is that syncope was due to potentially life-threatening arrhythmia, and thus an electrophysiology study may have been warranted. Finally, about 10–20% of patients undergoing ASA develop complete heart block (CHB) following the procedure, usually within a few hours to a few days later. The development of new conduction abnormalities as occurred here increases the risk of CHB. I would favor close observation for at least 3 days prior to discharge.

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