Impact of Right Atrial Physiology on Heart Failure and Adverse Events after Myocardial Infarction

Abstract

Background: Right ventricular (RV) function is a known predictor of adverse events in heart failure and following acute myocardial infarction (AMI). While right atrial (RA) involvement is well characterized in pulmonary arterial hypertension, its relative contributions to adverse events following AMI especially in patients with heart failure and congestion need further evaluation. Methods: In this cardiovascular magnetic resonance (CMR)-substudy of AIDA STEMI and TATORT NSTEMI, 1235 AMI patients underwent CMR after primary percutaneous coronary intervention (PCI) in 15 centers across Germany (n = 795 with ST-elevation myocardial infarction and 440 with non-ST-elevation MI). Right atrial (RA) performance was evaluated using CMR myocardial feature tracking (CMR-FT) for the assessment of RA reservoir (total strain ε_s), conduit (passive strain ε_e), booster pump function (active strain ε_a), and associated strain rates (SR) in a blinded core-laboratory. The primary endpoint was the occurrence of major adverse cardiac events (MACE) 12 months post AMI. Results: RA reservoir (ε_s p = 0.061, SRs p = 0.049) and conduit functions (ε_e p = 0.006, SRe p = 0.030) were impaired in patients with MACE as opposed to RA booster pump (ε_a p = 0.579, SRa p = 0.118) and RA volume index (p = 0.866). RA conduit function was associated with the clinical onset of heart failure and MACE independently of RV systolic function and atrial fibrillation (AF) (multivariable analysis hazard ratio 0.95, 95% confidence interval 0.92 to 0.99, p = 0.009), while RV systolic function and AF were not independent prognosticators. Furthermore, RA conduit strain identified low- and high-risk groups within patients with reduced RV systolic function (p = 0.019 on log rank testing). Conclusions: RA impairment is a distinct feature and independent risk factor in patients following AMI and can be easily assessed using CMR-FT-derived quantification of RA strain.

Keywords: cardiac magnetic resonance; feature tracking; myocardial infarction; prognosis; right atrium; risk stratification; strain; strain rate.

Figure 1

Feature-Tracking and Strain analysis on the left, display of a four chamber view (CV) with endocardially-tracked borders in the right atrium shown at end-diastole and systole, on the right, display of the corresponding curves of reservoir (ε_s), conduit (ε_e), and booster pump (ε_a) for a patient with (A) normal left ventricular ejection fraction of 56% and no major adverse cardiac event during follow-up, and (B) normal left ventricular ejection fraction of 52% and a major adverse clinical event during follow-up.

Figure 2

Study Flow-Chart. CMR = cardiovascular magnetic resonance, MACE = major adverse cardiovascular events, N/STEMI = non/ ST-elevation myocardial infarction.

Figure 3

Influence of RA Strain on MACE prediction. The graphs show the influence of right atrial (RA) reservoir (ε_s), conduit (ε_e) and booster pump (ε_a) strain on the rate of major adverse clinical events (MACE) during 12 months follow-up after ROC-adapted dichotomization, p values calculated by log-rank test.

Figure 4

Benefit of additional right atrial strain analysis over sole right ventricular function. The graphs show the impact of right atrial (RA) reservoir (ε_s), conduit (ε_e) and booster pump (ε_a) function evaluation on the occurrence of major adverse cardiac events (MACE). RA function was investigated in addition to right ventricular ejection fraction (RVEF) below the median. Cut-Offs for RA strains were chosen for optimal sensitivity and specificity, and p values were calculated by log-rank test for the occurrence of major adverse clinical events (MACE) within 12 months after myocardial infarction.