Patterns of coronary compromise leading to bradyarrhythmias and hypotension in inferior myocardial infarction

Right Ventricular Myocardial Infarction-A Tale of Two Ventricles: JACC Focus Seminar 1/5

Right ventricular infarction (RVI) complicates 50% of cases of acute inferior ST-segment elevation myocardial infarction, and is associated with high in-hospital morbidity and mortality. Ischemic right ventricular (RV) systolic dysfunction decreases left ventricular preload delivery, resulting in low-output hypotension with clear lungs, and disproportionate right heart failure. RV systolic performance is generated by left ventricular contractile contributions mediated by the septum. Augmented right atrial contraction optimizes RV performance, whereas very proximal occlusions induce right atrial ischemia exacerbating hemodynamic compromise. RVI is associated with vagal mediated bradyarrhythmias, both during acute occlusion and abruptly with reperfusion. The ischemic dilated RV is also prone to malignant ventricular arrhythmias. Nevertheless, RV is remarkably resistant to infarction. Reperfusion facilitates RV recovery, even after prolonged occlusion and in patients with severe shock. However, in some cases hemodynamic compromise persists, necessitating pharmacological and mechanical circulatory support with dedicated RV assist devices as a "bridge to recovery."

A case of recurring perioperative circulatory arrest: mind the autonomic nervous system

We report the case of an elderly woman who developed recurring episodes of unexplained cardiocirculatory arrest. The index event appeared during surgery to fix a fracture of the ankle and consisted of bradypnea, hypotension and asystole, coherent with a Bezold-Jarisch-like cardioprotective reflex. Classical signs of acute myocardial infarction were absent. Yet, occlusion of the right coronary artery (RCA) was observed and successfully revascularized, whereupon circulatory arrests vanished. We discuss several differential diagnoses. Unexplainable circulatory failure, with sinus bradycardia and arterial hypotension, despite lack of ECG signs of ischemia or significant troponin levels, suggest the action of cardioprotective reflexes of the autonomic nervous system. Coronary artery disease is a common source. Attention to cardioprotective reflexes should be taken in the case of unexplained cardiac arrest without overt reasons. We recommend performing coronary angiography to exclude significant coronary stenosis.

Short- and Long-Term Outcomes in Patients With Right Ventricular Infarction According to Modalities of Reperfusion Strategies in China: Data From China Acute Myocardial Infarction Registry

Purpose

We sought to investigate the short- and long-term outcomes in patients with right ventricular infarction in China.

Methods

Data from China Acute Myocardial Infarction (CAMI) Registry for patients with right ventricular infarction between January 2013 and September 2014 were analyzed.

Results

Of the 1,988 patients with right ventricular infarction, 733 patients did not receive reperfusion therapy, 281 patients received thrombolysis therapy, and 974 patients underwent primary PCI. Primary PCI and thrombolysis were all associated with lower risks of in-hospital (3.1 vs. 12.6%; adjusted OR: 0.48; 95% CI: 0.27–0.87; P = 0.0151 and 5.7 vs. 12.6%; adjusted OR: 0.43; 95% CI: 0.22–0.85; P = 0.0155, respectively), and 2-year all-cause mortality (6.3 vs. 20.9%; adjusted HR: 0.50; 95% CI: 0.34–0.73; P = 0.0003 and 11.0 vs. 20.9%; adjusted HR: 0.59; 95% CI: 0.38–0.92; P = 0.0189, respectively), compared with no reperfusion therapy. Meanwhile, primary PCI was superior to thrombolysis in reducing the risks of in-hospital atrial-ventricular block (4.2 vs. 8.9%; adjusted OR: 0.46; 95% CI: 0.23–0.91; P = 0.0257), cardiogenic shock (5.3 vs. 13.9%; adjusted OR: 0.43; 95% CI: 0.23–0.83; P = 0.0115), and heart failure (8.5 vs. 23.5%; adjusted OR: 0.35; 95% CI: 0.22–0.56; P < 0.0001). Primary PCI could reduce the risk of 2-year major adverse cardiac and cerebrovascular event (19.1 vs. 33.3%; adjusted HR: 0.72; 95% CI: 0.56–0.92; P = 0.0092) relative to no reperfusion therapy, whereas thrombolysis may increase the risk of 2-year revascularization (15.5 vs. 8.7%; adjusted HR: 1.90; 95% CI: 1.15–3.16; P = 0.0124) compared with no reperfusion therapy.

Conclusions

Timely reperfusion therapy is essential for patients with right ventricular infarction. Primary PCI may be considered as the default treatment strategy for patients with right ventricular infarction in the contemporary primary PCI era.

Long-term outcomes in inferior ST-segment elevation myocardial infarction patients with right ventricular myocardial infarction

OBJECTIVE

To evaluate the prognostic influence of the presence of right ventricular myocardial infarction (RVMI) on patients with inferior ST-segment elevation myocardial infarction (STEMI) in the contemporary reperfusion era.

METHODS

9308 patients with inferior STEMI were included from the prospective, nationwide, multicenter China Acute Myocardial Infarction Registry, including 1745 (18.75%) patients with RVMI and 7563 (81.25%) patients without RVMI. The primary outcome was two-year all-cause mortality. The secondary outcome was major adverse cardiac and cerebrovascular event (MACCE) defined as a composite of all-cause mortality, recurrent MI, revascularization, stroke, and major bleeding.

RESULTS

After two-year follow up, there were no significant differences between inferior STEMI patients with or without RVMI in all-cause mortality (12.0% vs 11.3%; adjusted HR: 1.05; 95% CI: 0.90 to 1.24; P = 0.5103). Inferior STEMI with RVMI was associated with higher risk of MACCE (25.6% vs 22.0%; adjusted HR: 1.17; 95% CI: 1.05 to 1.31; P = 0.0038), revascularization (10.3% vs 8.1%; adjusted HR: 1.23; 95% CI: 1.03 to 1.48; P = 0.0218), and major bleeding (4.6% vs 2.7%; adjusted HR: 1.56; 95% CI: 1.18 to 2.07; P = 0.0019). Primary percutaneous coronary intervention (PCI) and thrombolysis were independent predictors to decrease all-cause mortality. For patients who received timely reperfusion, RVMI involvement did not increase all-cause mortality, whereas for those who did not undergo reperfusion, RVMI increased all-cause mortality (20.3% vs 15.7%; HR: 1.34; 95% CI: 1.10 to 1.63).

CONCLUSION

RVMI did not increase all-cause mortality for inferior STEMI patients in contemporary reperfusion era, whereas the risk was increased for patients with no reperfusion treatment.

Comparing the clinical and prognostic impact of proximal versus nonproximal lesions in dominant right coronary artery ST-elevation myocardial infarction

OBJECTIVE

To evaluate the prognostic significance of culprit lesion location in dominant right coronary artery (RCA) ST-elevation myocardial infarction (STEMI).

BACKGROUND

In RCA STEMI, proximal culprit lesions have been shown to have higher rates of acute complications such as bradycardia and cardiogenic shock (CS) but data on mortality is limited.

METHODS

We retrospectively identified and analyzed data from consecutive patients with a dominant RCA STEMI who underwent either primary or rescue percutaneous coronary intervention (PCI) between January 2003 and December 2016. We compared the rates of sustained ventricular tachycardia (VT), CS, intra-aortic balloon pump (IABP), temporary cardiac pacing (TCP) and death between culprit lesions located proximal and distal to the origin of the last right ventricular (RV) marginal artery >1 mm in diameter.

RESULTS

The 939 patients were included; 599 (63.7%) had a proximal lesion and 340 (36.3%) had a nonproximal lesion. The 801 (85.3%) underwent primary PCI and 138 (14.7%) underwent rescue PCI. There was no difference in first medical contact to balloon or fibrinolysis times between the groups; p = .98 and .71. There was no significant difference in the rate of sustained VT (3.0%vs. 3.2%, p = .85) but proximal lesions were more likely to develop CS (10.9%vs. 5.8%, p = .01), require IABP (7.3%vs.2.9%, p < .01) and TCP (6.3%vs. 2.6%, p = .01). Thirty-day mortality was higher for proximal lesions (5.0%vs. 0.9%, p < .01) particularly for those with CS (35.3%vs. 10.0%, p = .05).

CONCLUSION

Culprit lesions located proximal to the origin of the last RV marginal artery had a higher rate of acute complications such as CS and mortality.

Periprocedural temporary pacing in primary percutaneous coronary intervention for patients with acute inferior myocardial infarction

OBJECTIVE

High-degree atrioventricular block (AVB), including complete AVB in acute inferior ST-elevation myocardial infarction (STEMI), is not uncommon. However, there is no study evaluating the clinical differences between patients who have undergone temporary pacing (TP) and patients who have not. The present study was designed to investigate whether TP has any prognostic significance in inferior STEMI complicated by complete AVB.

METHODS

From January 2009 to December 2014, 295 consecutive patients diagnosed with inferior wall STEMI in a university hospital were reviewed. All of them underwent primary percutaneous coronary intervention (PCI). Among the 295 patients, there were 72 patients with complete AVB. The clinical characteristics, procedural data, and long-term major adverse cardiocerebrovascular events were compared in patients with and without TP.

RESULTS

Baseline clinical and procedural characteristics were similar between patients with and without TP. Patients with TP were more likely to present with cardiogenic shock; thus, additional interventions were attempted via a femoral approach, as patients received further treatment with intra-aortic balloon pumps and were subjected to additional cardiopulmonary resuscitation. Most cases of complete AVB were primarily caused by right coronary artery occlusion. After a median follow-up period of 344 (range, 105.5-641) days, major adverse cardiocerebrovascular events did not differ between the groups (P=0.528).

CONCLUSION

We conclude that primary PCI without TP is acceptable in complete AVB-complicated acute inferior STEMI. To avoid delay in reperfusion, we suggest that primary PCI should be the first priority therapy rather than treating patients initially with TP.

Primary percutaneous coronary intervention ameliorates complete atrioventricular block complicating acute inferior myocardial infarction

Objective

Complete atrioventricular block (CAVB) in acute inferior ST-segment elevation myocardial infarction (STEMI) is associated with poor clinical outcomes after noninvasive treatment. This study was designed to determine the effect of primary percutaneous coronary intervention (PCI) in patients with CAVB complicating acute inferior STEMI, at a single center.

Methods

We enrolled 138 consecutive patients diagnosed with STEMI involving the inferior wall; of these, 27 patients had CAVB. All patients received primary PCI. The clinical characteristics, procedural data, and clinical outcomes were compared in patients with versus without CAVB.

Results

Baseline clinical characteristics were similar between patients with and without CAVB. Patients with CAVB were more likely to present with cardiogenic shock, and CAVB was caused primarily by right coronary artery occlusion. Door-to-balloon time was similar between those two groups. After primary PCI, CAVB was reversed in all patients. The peak creatinine phosphokinase level, left ventricular ejection fraction and in-hospital mortality rate were similar between the two groups. After a median follow up of 318 days, major adverse cardiac events did not differ between the groups (8.1% in patients without CAVB; 11.1% in patients with CAVB) (P=0.702).

Conclusion

We conclude that primary PCI can ameliorate CAVB-complicated acute inferior STEMI, with an acceptable rate of major adverse cardiac events, and suggest that primary PCI should be the preferred reperfusion therapy in patients with CAVB complicating acute inferior myocardial infarction.

Acute right ventricular infarction: insights for the interventional era

Acute right ventricular infarction is associated with higher in-hospital morbidity and mortality related to life-threatening hemodynamic compromise and arrhythmias during acute occlusion and abruptly with reperfusion, complications which have implications for interventional management. Acute right coronary artery occlusion proximal to the right ventricular (RV) branches results in depressed RV systolic function, leading to diminished transpulmonary delivery of left ventricular preload and resulting in low-output hypotension. Under these conditions, RV pressure generation and output are dependent on left ventricular-septal contraction via paradoxical septal motion. With culprit lesions distal to the right atrial (RA) branches, augmented RA contractility enhances RV performance and cardiac output, whereas proximal occlusions induce RA ischemia, which exacerbates hemodynamic compromise. Hypotension may respond to volume resuscitation and restoration of a physiologic rhythm. Refractory cases usually respond to parenteral inotropes, though in some cases mechanical support is required. The right ventricle is relatively resistant to infarction and usually recovers even after prolonged occlusion. Acute percutaneous mechanical reperfusion enhances recovery of RV performance and improves the clinical course and survival of patients with right ventricular infarction.

Arrhythmias in the coronary care unit

Symptomatic sustained cardiac arrhythmias are frequently observed in in the coronary care unit and often lead to hemodynamic compromise, especially in the presence of multisystem disease. The predominant arrhythmias noted in intensive care units are tachyarrhythmias, particularly atrial fibrillation and flutter, and ventricular tachycardia. Bradycardias, arguably less life-threatening than tachyarrhythmias, can arise from sinus node dysfunction or atrioventricular conduction block; transient vagally-mediated bradycardias are frequently encountered as well. Prompt diagnosis of the patient with tachycardia is critical as treatment depends on the accurate diagnosis of tachycardia mechanism. The electrocardiogram remains the most important diagnostic tool for the evaluation of both wide and narrow complex tachycardia. The electrocardiographic diagnosis of wide complex tachycardia is based on evaluation of atrioventricular relationship and QRS morphology while the diagnosis of narrow complex tachycardia is based on the location and morphology of P waves. It is important for critical care specialists to understand the principles of cardiac arrhythmia diagnosis and remain current with the recent advances in the pharmacologic and non-pharmacologic management of patients with arrhythmias.

Malignant ventricular arrhythmias in patients with acute right ventricular infarction undergoing mechanical reperfusion

Patients with acute right ventricular (RV) infarctions are prone to ventricular arrhythmias, but little is known regarding the temporal patterns of these arrhythmias, their impact on outcomes, or their relation to the severity of RV impairment. The aim of this study was to examine the impact of malignant ventricular arrhythmias (MVAs) complicating acute RV infarction. A further aim was to determine whether the degree of RV impairment was a predisposing factor to MVAs. The charts of 48 patients with acute RV infarctions were reviewed for documented MVAs. Temporal presentation, relating to reperfusion, and in-hospital outcomes were tabulated. Echocardiograms were reviewed to quantify RV impairment. MVAs occurred in 38% of patients, with multiple episodes (electrical storm) in 8.3%. MVAs developed before reperfusion (72% of patients), abruptly with reperfusion (11%), or after reperfusion (22%). Patients with MVAs had larger infarcts (peak creatine phosphokinase 3,027 vs 1,848 U/L, p = 0.03) and trended toward worse RV function (fractional shortening 27% vs 34%, p = 0.08). In-hospital mortality (patients with MVAs 17% vs 6.7%, p = 0.35), intensive care days (patients with MVAs 7.1 +/- 10 vs 3.9 +/- 2.5, p = 0.39), and hospital days (patients with MVAs 10.3 +/- 10 vs 8.0 +/- 5.1, p = 0.57) were similar between groups. Patients with electrical storm had longer intensive care stays (18.0 +/- 18.5 vs 4.0 +/- 2.5 days, p = 0.02) and hospital stays (20.5 +/- 17 vs 7.9 +/- 5.0 days, p = 0.05). In conclusion, MVAs are common in acute RV infarctions. They frequently occur before reperfusion and are associated with larger infarcts. With reperfusion, MVAs had little impact on intensive care and hospital stays or in-hospital mortality, except in patients with electrical storm.

Impact of mechanical reperfusion on clinical outcome in elderly patients with right ventricular infarction

BACKGROUND

Previous reports suggest that elderly patients with acute right ventricular infarction suffer in-hospital mortality of 50% and that hemodynamic compromise is irreversible. We hypothesized that mechanical reperfusion would improve such outcomes.

METHODS

We retrospectively analyzed in-hospital morbidity and mortality in 54 patients >70 years of age with acute inferior myocardial infarction undergoing primary angioplasty. The presence of right ventricular infarction was determined by a two dimensional echocardiogram.

RESULTS

Overall, 18 (33%) patients had inferior myocardial infarction and right ventricular infarction, whereas 36 (67%) patients had inferior myocardial infarction alone. All patients with inferior myocardial infarction alone were successfully reperfused, whereas one patient with right ventricular infarction suffered reperfusion failure. Right ventricular infarction patients more commonly suffered hemodynamic and arrhythmic complications (hypotension in 33 vs. 2.8%, P<0.01; ventricular arrhythmias in 61 vs. 25%, P<0.01; and bradyarrhythmias in 78 vs. 25%, P<0.01). Overall, 72% of right ventricular infarction patients survived, including many with hemodynamic compromise. In-hospital mortality, however, was greater in those with right ventricular infarction than in those without (28 vs. 8.3%, P=0.19).

CONCLUSION

Elderly patients with inferior myocardial infarction complicated by right ventricular infarction suffer greater morbidity and mortality than those without. With successful mechanical reperfusion, however, the majority survives, including those with hemodynamic compromise.