Strain-based discoordination imaging during exercise in heart failure with reduced ejection fraction: Feasibility and reproducibility

Abstract

Purpose Various parameters of mechanical dyssynchrony have been proposed to improve patient selection criteria for cardiac resynchronization therapy, but sensitivity and specificity are lacking. However, echocardiographic parameters are consistently investigated at rest, whereas heart failure (HF) symptoms predominately manifest during submaximal exertion. Although strain-based predictors of response are promising, feasibility and reproducibility during exercise has yet to be demonstrated. Methods Speckle-tracking echocardiography was performed in patients with HF at two separate visits. Echocardiography was performed at rest, during various exercise intensity levels, and during recovery from exercise. Systolic rebound stretch of the septum (SRSsept), systolic shortening, and septal discoordination index (SDI) were calculated. Results Echocardiography was feasible in about 70–80% of all examinations performed during exercise. Of these acquired views, 84% of the cine-loops were suitable for analysis of strain-based mechanical dyssynchrony. Test–retest variability and intra- and inter-operator reproducibility at 30% and 60% of the ventilatory threshold (VT) were about 2.5%. SDI improved in the majority of patients at 30% and 60% of the VT, with moderate to good agreement between both intensity levels. Conclusion Although various challenges remain, exercise echocardiography with strain analysis appears to be feasible in the majority of patients with dyssynchronous heart failure. Inter- and intra-observer agreement of SRSsept and SDI up to 60% of the VT were comparable to resting values. During exercise, the extent of SDI was variable, suggesting a heterogeneous response to exercise. Further research is warranted to establish its clinical significance.

Does recovery from submaximal exercise predict response to cardiac resynchronisation therapy?

“…Incorporation of exercise parameters may further improve patient selection, but these are not yet part of routine clinical decision making for CRT. 5 However, several studies showed a positive relationship between pre-implantation maximal exercise capacity (peak oxygen uptake; VO 2 peak) and CRT response, 6 7 suggesting that more severely impaired HF patients are less likely to achieve an echocardiographic response. This may be because their exercise capacity is more severely limited by peripheral derangements.…”

“…A barrier for the widespread implementation of assessment of maximal exercise capacity is that symptom limiting exercise testing is burdensome, and often not truly achievable for patients with severe HF. 5 8 Therefore, ‘submaximal’ exercise testing could be a valuable alternative. One of the submaximal exercise parameters that reflect exercise capacity are oxygen kinetics.…”

“…Research has focused on deriving new and more advanced markers from the ECG or echocardiogram to better predict response after CRT 3. However, sensitivity and specificity should be further improved in order to truly affect clinical decision making 4 5…”

“…This may be because their exercise capacity is more severely limited by peripheral derangements. Yet, studies investigating the influence of baseline ‘exercise’ characteristics on echocardiographic response are relatively scarce, as opposed to trials investigating electrical and mechanical substrates 3 5…”