Right ventricular dysfunction and exercise capacity after inferior (posterior) wall acute myocardial infarction

Clinical challenges facing patient participation in cardiac rehabilitation: cigarette smoking

INTRODUCTION

Cardiac rehabilitation (CR) is highly effective at reducing morbidity and mortality. However, CR is underutilized, and adherence remains challenging. In no group is CR attendance more challenging than among patients who smoke. Despite being more likely to be referred to CR, they are less likely to enroll, and much more likely to drop out. CR programs generally do not optimally engage and treat those who smoke, but this population is critical to engage given the high-risk nature of continued smoking in those with cardiovascular disease.

AREAS COVERED

This review covers four areas relating to CR in those who smoke. First, we review the evidence of the association between smoking and lack of participation in CR. Second, we examine how smoking has historically been identified in this population and propose objective screening measures for all patients. Third, we discuss the optimal treatment of smoking within CR. Fourth, we review select populations within those who smoke (those with lower-socioeconomic status, females) that require additional research and attention.

EXPERT OPINION

Smoking poses a challenge on multiple fronts, being a significant predictor of future morbidity and mortality, as well as being strongly associated with not completing the secondary prevention program (CR) that could benefit those who smoke the most.

Echocardiographic predictors of exercise intolerance in patients with heart failure with severely reduced ejection fraction

Decreased exercise capacity (EC) is an established predictor of cardiac and all-cause mortality in patients with chronic heart failure (HF). No correlation has been found between EC and left ventricular (LV) ejection fraction. Moreover, data about the effect of right ventricular (RV) function on EC in HF with severe LV dysfunction are limited and contradictory. In this study, we aimed to investigate the relationship between EC and myocardial mechanics in patients with HF with reduced ejection fraction.Consecutive patients with symptomatic HF and LV ejection fraction ≤35% were prospectively assessed. All patients were evaluated with enhanced echocardiography. A symptom-limited treadmill cardiopulmonary exercise test (CPX) was performed within 24-hour interval. Patients were stratified into 4 groups according to their EC defined by Weber's classification. Prognosis of EC, expressed as oxygen uptake at peak exercise (peak VO2), was evaluated in multivariate linear regression analysis model.Sixty-seven patients with New York Heart Association classes II to III and a mean LV ejection fraction of 26 ± 7% were enrolled. A wide range of peak VO2 was observed in CPX with patient exercise performance distributed to all classes according to Weber's classification. Significant differences were found in RV systolic and diastolic functions between groups with different classes of EC: RV peak systolic myocardial velocity (S') (P < .001), tricuspid annular plane systolic excursion (TAPSE) (P = .003), RV E' (P = .003). In patients with functional decline, systolic pulmonary artery pressure (PASP) was higher (P = .029) and TAPSE/PASP ratio was lower (P = .006). No significant differences were found in LV diameter, systolic and diastolic function, and degree of mitral regurgitation. Thirty three patients with RV systolic dysfunction showed lower peak VO2 and oxygen uptake at anaerobic threshold (P = .008, P = .006, respectively), shorter exercise time (P = .003), and lower systolic blood pressure (P = .01) than in patients with normal RV systolic function. Logistic multivariate linear regression analysis with stepwise inclusion and exclusion revealed that gender, RV S', and RV free wall strain were independent predictors of peak VO2.RV function, assessed as S' and free wall strain, was independently related to EC, measured using CPX, in patients with HF and severe LV systolic dysfunction.

Smoking and cardiac rehabilitation participation: Associations with referral, attendance and adherence

OBJECTIVE

Continued smoking after a cardiac event greatly increases mortality risk. Smoking cessation and participation in cardiac rehabilitation (CR) are effective in reducing morbidity and mortality. However, these two behaviors may interact; those who smoke may be less likely to access or complete CR. This review explores the association between smoking status and CR referral, attendance, and adherence.

METHODS

A systematic literature search was conducted examining associations between smoking status and CR referral, attendance and completion in peer-reviewed studies published through July 1st, 2014. For inclusion, studies had to report data on outpatient CR referral, attendance or completion rates and smoking status had to be considered as a variable associated with these outcomes.

RESULTS

Fifty-six studies met inclusion criteria. In summary, a history of smoking was associated with an increased likelihood of referral to CR. However, smoking status also predicted not attending CR and was a strong predictor of CR dropout.

CONCLUSION

Continued smoking after a cardiac event predicts lack of attendance in, and completion of CR. The issue of smoking following a coronary event deserves renewed attention.

Determinants of right ventricular remodeling following ST-segment elevation myocardial infarction

Right ventricular (RV) function after ST-segment elevation myocardial infarction (STEMI) has important prognostic implications. However, the changes in RV function over time after STEMI and the incidence of RV remodeling remain unknown. The present study evaluated changes in RV dimensions and function in contemporary patients with first STEMI and assessed the independent determinants of RV dysfunction at follow-up. Patients with first STEMI (n = 940, 60 ± 11 years, 77% men) treated with primary percutaneous coronary intervention underwent echocardiography at baseline and 6- and 12-month follow-up. The prevalence of RV dysfunction (tricuspid annular plane systolic excursion [TAPSE] ≤15 mm) decreased significantly at 6 months follow-up (from 15% to 8%, p <0.001) and the incidence of RV remodeling (increase in RV end-diastolic area [RVEDA] ≥20%) was observed in 200 patients (25%). Absolute changes in RVEDA were independently associated with absolute changes in wall motion score index and left ventricular (LV) remodeling (p <0.001 for both parameters), whereas absolute changes in TAPSE were independently related with absolute changes in wall motion score index and mitral regurgitation grade (p <0.001 for both parameters). Independent correlates of RV dysfunction at 6 months follow-up were multivessel coronary disease (odds ratio [OR] 2.13), peak cardiac troponin T (OR 1.05), angiotensin-converting enzyme inhibitors and/or angiotensin receptor blockers use (OR 0.27), baseline LV ejection fraction (OR 0.96) and baseline TAPSE (OR 0.88). In conclusion, despite the non-negligible incidence of RV remodeling in patients with first STEMI, RV function improves early after STEMI. Multivessel coronary disease, infarct size, baseline LV ejection fraction and TAPSE and the nonuse of angiotensin-converting enzyme inhibitors and/or angiotensin receptor blockers are independent determinants of RV dysfunction.

Right ventricular function in left ventricular disease: pathophysiology and implications

The functions of the left and right ventricles are intimately linked. The right ventricle (RV) has transverse muscle fibres in its free wall and also shares oblique fibres in the interventricular septum with the left ventricle (LV). The latter constitute a link between left and right ventricular contractile function such that LV contraction augments RV contraction - a phenomenon called systolic ventricular interaction. When RV afterload is increased (by raised pulmonary artery pressure) overall contractile performance becomes increasingly dependent on this systolic ventricular interaction because the oblique septal fibres are more mechanically efficient than the free wall transverse fibres in conditions of high RV afterload. When LV end diastolic pressure is increased by heart failure due to LV systolic dysfunction, pulmonary artery pressure becomes raised, imposing an increased afterload on the RV. In such patients global LV performance is reduced, consequently systolic ventricular interaction is reduced resulting in a reduction in RV contractile performance even if the RV is not directly involved in the disease process causing LV systolic dysfunction. Furthermore, as the left ventricle becomes progressively more spherical the septal fibres become less oblique, dramatically reducing their mechanical advantage and further impairing RV contractile function. This ultimately leads to clinical right ventricular failure. This in turn typically results in tricuspid regurgitation and a vicious cycle of right ventricular enlargement with further reduction in the oblique nature of the septal fibres. In addition to the systolic interaction of the LV on the RV, when the RV is enlarged and stretches the pericardium, pericardial and right ventricular diastolic pressures may become markedly increased and this can result in constraint to filling of the LV by the pericardium (pericardial constraint) and by the RV via the interventricular septum (diastolic ventricular interaction).