Isolated Right Ventricular Infarction: Percutaneous Coronary Intervention in Three Different Types of Clinical Presentation

Right ventricular myocardial infarction (RVI) is usually associated with inferior left ventricular involvement and leads to an increased in-hospital mortality rate.1 Rarely, an isolated RVI may occur. In these cases, electrocardiogram may show ST-segment elevation at precordial leads, thus mimicking an anterior location myocardial infarction.2–4 Clinical presentation of isolated RVI may potentially include three possibilities: predominantly ischemic (chest pain with ST abnormalities), predominantly arrhythmic (especially bradyarrhythmia), and predominantly hemodynamic (hypotension and other signs of acute right ventricular failure). Primary percutaneous coronary intervention (PCI) is the best reperfusion strategy for acute myocardial infarction.5 One of its advantages is that it offers an immediate knowledge of the coronary anatomy, thus allowing a prompt identification of the culprit vessel.6 Because of that, the report of cases of pure RVI has increased in the era of PCI.7–9 We present three patients with pure RVI, presenting in three different clinical settings who were successfully treated with primary PCI in an occluded non-dominant right coronary artery. Patient A. Ischemic presentation. A 42-year-old patient, current smoker, with diabetes mellitus type II on diet treatment, was admitted to our institution with chest pain lasting 4 hours. Electrocardiography at admission showed ST-segment elevation at V1, V2, V3 and V4 leads (Figure 1A). A fourth heart sound, but no hemodynamic instability was present (blood pressure was 145/80 mmHg; 92 beats per minute). The jugular vein was not distended and there was no Kussmaul sign. With a diagnosis of anterior myocardial infarction, the patient was referred for primary PCI, the routine reperfusion strategy of myocardial infarction at our institution. Coronary angiography showed a dominant left coronary artery without significant coronary lesions (Figure 2A). Left ventriculography showed normal contractility of the left ventricle, with a preserved left ventricular ejection fraction (Figure 3A). The right coronary artery was non-dominant and had a proximal occlusion (Figure 4A). A Judkins right 6 French guiding catheter (Cordis Corporation, Miami Lakes, Florida) was placed in the right coronary artery, and a Balance Middle Weight™ guidewire (Guidant Corporation, Santa Clara, Calif.) was placed distally. A 2.0 x 15 mm Maverick balloon (Boston Scientific Corporation, Maple Grove, Minn.) was inflated at the level of the occlusion. After visualizing the distal vessel, an Express™ 3.0 x 20 mm stent (Boston Scientific Corporation) was delivered and implanted with excellent angiographic results. ST-segment elevation normalized after PCI. A transthoracic echocardiographic study performed immediately after PCI showed right ventricle dilation and hypokinesia that were resolved within 24 hours. The subsequent clinical course was uneventful; there was no hemodynamic impairment and the creatinine phosphokinase plasmatic peak value increased to 303 IU. Patient B. Arrhythmic presentation. An 80-year-old patient with type II diabetes mellitus on oral antiglycemic agents presented to the emergency department with chest pain and syncope. At admission, the electrocardiogram showed complete atrioventricular block, with a ventricular rhythm of 30 beats per minute and no evident ST-segment abnormalities (Figure 1B). A temporary venous pacemaker was placed on the right ventricle. Transthoracic echocardiography showed a severely enlarged right ventricle and coronary angiography was then performed. Left ventricle contractility was normal (Figure 2B). Coronary angiography showed a dominant left coronary artery, an interventricular septum that was supplied by the left circumflex, obtuse marginal branches, and a recurrent left anterior descending coronary artery (Figure 3B). The non-dominant right coronary artery was proximally occluded (Figure 4B). Using a Judkins right 6 French guiding catheter (Cordis Corporation) and a Choice guidewire (Boston Scientific Corporation), a 2.5 x 20 mm Stormer™ balloon (Medtronic AVE, Inc., Santa Rosa, Calif.) was inflated, and an Express 3.0 x 12 mm stent was implanted with excellent angiographic results (Figure 5B). The subsequent clinical course during hospitalization was uneventful, except for an episode of paroxysmal atrial fibrillation. The atrioventricular block resolved, and the temporary pacemaker was removed. The patient’s right ventricle diameter and function normalized, and his peak creatine-phosphokinase plasmatic value was 942 IU. Patient C. Hemodynamic presentation. The third patient was a 79-year-old male, former smoker, with previously diagnosed hypertension and severe left ventricular hypertrophy. The patient was admitted due to chest pain associated with ST-segment elevation at V1–V4, and II, III and aVF leads (Figure 1C). Chest pain disappeared and ST normalized with nitroglycerin s1. Creatine-phosphokinase rose to 397 IU. The patient was referred to our center for cardiac catheterization 24 hours later, having experienced no pain at the time of angiography. Left ventriculography revealed normal contractility of the left ventricle (Figure 2C). Importantly, there were significant pressure increases in the right ventricle (end diastole of 28 mmHg) and the right atrium (28 mmHg) (Figure 6). Coronary angiography showed a normal dominant left coronary artery (Figure 3C), as well as a non-dominant right coronary artery with a tight thrombotic lesion (Figure 4C). Taking into consideration the possibility that the hemodynamic pattern of right ventricular failure was due at least in part to severe right ventricular ischemia (stunned myocardium), we decided to treat the non-dominant right coronary artery. A Judkins right 6 French guiding catheter was placed in the right coronary artery and a Balance Middle Weight guidewire was placed in the acute marginal branch. A 2.5 x 15 mm Maverick balloon was inflated and an Express 3.0 x 12 mm stent was successfully implanted (Figure 5C). Transthoracic echocardiography following the procedure revealed an enlarged and hypokinetic right ventricle in addition to the previously diagnosed severe left ventricular hypertrophy. The patient’s subsequent clinical course during hospitalization was uneventful. All three of these patients received IV heparin 100 IU/kg and a 300 mg loading dose of clopidogrel was administered p.o. immediately after stent placement. Antiplatelet therapy following stent placement included aspirin 200 mg and clopidogrel 75 mg daily. Discussion. Isolated RVI: Electrocardiographic and clinical presentation. Among the patients who suffer inferior acute myocardial infarction, 30–50% also have right ventricular involvement.1 Proper clinical manifestations of RVI include signs of acute right ventricular failure such as hypotension, jugular vein distension, right-sided fourth heart sound and sometimes Kussmaul sign. On the other hand, patients with inferior myocardial infarction with right ventricular involvement have an increased incidence of atrioventricular block, bradycardia, ventricular arrhythmia and shock, all of which result in higher mortality rates.10 Although it is very uncommon, some patients may suffer an isolated RVI. This may occur when a non-dominant or co-dominant right coronary artery proximally to an acute marginal branch, or an acute marginal branch is occluded.2–4,7–9 An isolated RVI may also occur secondarily to an acute occlusion of the RV branch following angioplasty.11 The previously reported incidence of isolated RVI is very low (RVI: Are reperfusion strategies justified? Some authors advocate a conservative treatment once the diagnosis of isolated RVI is established, even once the coronary angiographic study is performed.8 On the contrary, we performed PCI in our patients based on two criteria: 1) patients with inferior wall myocardial infarction and right ventricular involvement in whom there was a greater incidence of hypotension, shock, arrhythmia, and conduction disturbances — all leading to higher mortality rates.1 In patients with isolated RVI, these complications may also occur and may also be potentially lethal; 2) reperfusion strategies improve the outcome of patients with inferior myocardial infarction, especially in those with right ventricular involvement.14,15 Thrombolysis may be less effective in restoring coronary patency in patients with RVI, probably due in part to a more proximal occlusion of the right coronary artery, lower cardiac output, and a higher incidence of prolonged hypotension and bradyarrhythmia.16 Because of this, primary PCI could offer special advantage to patients with RVI. Thus, this reperfusion strategy has been proposed as the first-choice therapy in these patients.17 Although both the detrimental effects of RVI and the beneficial effects of coronary reperfusion have been demonstrated in patents with inferior involvement, and little is known about the prognosis of isolated RVI,18 it could be speculated that the benefit of coronary reperfusion is also applicable to patients with pure RVI.9 Patients with pure RVI are also at risk for hemodynamic impairment, arrhythmic complications, and more rarely, massive pulmonary embolism and myocardial rupture.19,20 Patient A did not develop cardiac complications after the procedure; in patient B, atrioventricular block resolved after PCI; and in patient C, signs of right ventricular failure disappeared within 24 hours post-PCI. Therefore, our data support the use of PCI once an isolated RVI is diagnosed, irrespective of the type of clinical presentation.

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