Presence of left ventricular contractile reserve, evaluated by means of dobutamine stress-echo test, is able to predict response to cardiac resynchronization therapy

Current role of echocardiography in cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is an established treatment for patients with heart failure and left ventricular systolic dysfunction. Patients are usually assessed by echocardiography, which provides a number of anatomical and functional information used for cardiac dyssynchrony assessment, prognostic stratification, identification of the optimal site of pacing in the left ventricle, optimization of the CRT device, and patient follow-up. Compared to other cardiac imaging techniques, echocardiography has the advantage to be non-invasive, repeatable, and safe, without exposure to ionizing radiation or nefrotoxic contrast. In this article, we review current evidence about the role of echocardiography before, during, and after the implantation of a CRT device.

Acute contractile recovery extent during biventricular pacing is not associated with follow-up in patients undergoing resynchronization

Background

It has been reported that contractility, as assessed using dobutamine infusion, is independently associated with reverse remodeling after CRT. Controversy, however, exists about the capacity of this approach to predict a long-term clinical response. This study's purpose was to assess whether long-term CRT clinical effects can be predicted according to acute inotropic response induced by biventricular stimulation (CRT on), as compared with AAI–VVI right stimulation pacing mode (CRT off), quantified at the time of implantation.

Methods

In 98 patients (ejection fraction 29 ± 10%), acute changes in left ventricular (LV) elastance (Ees), arterial elastance (Ea), and Ees/Ea, as assessed from slope changes of the force–frequency relation obtained when the heart rate increased, and also assessed while measuring triplane LV volumes and continuous noninvasive blood pressure, were related to death or rehospitalization during a 3-year follow-up. Other covariances tested were age, gender, disease etiology, QRS duration, amount of mitral regurgitation, LV diastolic volume, ejection fraction, and the degree of asynchrony and longitudinal strain at baseline.

Results

There was a marked increment in the Ees slope with CRT (interaction P = 0.004), no Ea change, and modest Ees/Ea increase (interaction P < 0.05). In Cox analysis, however, neither slope changes nor baseline values of Ees, Ea, and Ees/Ea were associated with long-term follow-up. Only ventricular diastolic volume (direct relation P = 0.002) and QRS duration (inverse relation P = 0.009) predicted death/rehospitalization.

Conclusions

Acute contractile recovery in CRT patients is not associated with 3 years prognosis. Instead, death or rehospitalization can be predicted from QRS duration and LV diastolic volume at baseline.

Global myocardial contractile reserve assessed by high-dose dobutamine stress echocardiography predicts response to the cardiac resynchronization therapy

BACKGROUND

Myocardial contractile reserve (CR) is a strong prognostic factor in patients with heart failure. The presence of significant myocardial fibrosis can lead to a reduced response to cardiac resynchronization therapy (CRT). We assumed that myocardial CR assessed by high-dose dobutamine stress echocardiography (DSE) would predict response to CRT.

METHODS

Fifty-two consecutive symptomatic patients with heart failure (New York Heart Association [NYHA] class III), with depressed ejection fraction (EF) of the left ventricle (26.3 ± 6.9%) and dyssynchronous contractions (QRS duration 149.8 ± 23.8 msec) underwent DSE before CRT implantation. The difference in EF at rest and at peak (40 μg/kg per minute) DSE indicated global CR. Responders to CRT were defined by a decrease in left ventricular end-systolic volume of ≥15% and/or an increase in EF of ≥5% after 6 months of CRT.

RESULTS

During high-dose dobutamine infusion, responders (28 patients, 54%) showed a greater increase in EF compared with nonresponders (Δ 11 ± 7% vs. Δ 2 ± 9%, P = 0.007). CR correlated moderately with an improvement in EF after 6 months of CRT (r = 0.50, P = 0.0009). Furthermore, responders showed significant improvement in clinical status, evaluated by a reduction in NYHA functional class (-0.8 ± 0.6 vs. 0.1 ± 0.4, P = 0.02), compared with nonresponders. A 7% exercise-induced increase in EF yielded sensitivity of 79% and specificity of 87% in predicting the response to CRT after 6 months.

CONCLUSIONS

Myocardial CR assessed by high-dose DSE can play a potentially important role in identifying responders to CRT.

Low-dose dobutamine test associated with interventricular dyssynchrony: a useful tool to identify cardiac resynchronization therapy responders: data from the LOw dose DObutamine stress-echo test in Cardiac Resynchronization Therapy (LODO-CRT) phase 2 study

BACKGROUND

Cardiac resynchronization therapy (CRT) is effective in patients with heart failure, but 30% to 50% of subjects are classified as nonresponders. Identifying responders remains a challenging task.

AIMS

The LODO-CRT trial investigated the association between left ventricular contractile reserve (LVCR) and clinical and echocardiographic long-term CRT response.

METHODS

This is a multicenter, prospective, observational study. Left ventricular contractile reserve was detected using a dobutamine stress echocardiography test, defined as an ejection fraction increase of >5 points. Clinical CRT response was defined as the absence of major cardiovascular events (ie, cardiovascular death or heart failure hospitalization). Echocardiographic response was defined as a left ventricle end-systolic volume reduction of >10%.

RESULTS

A total of 221 CRT-indicated patients were studied (80% presented LVCR). During a mean follow-up of 15 ± 5 months, 17 patients died and 16 were hospitalized due to heart failure. The proportion of clinical responders was 155 (88%) of 177 and 33 (75%) of 44 (P = .036) in the groups with and without LVCR, respectively. Kaplan-Meier analysis showed a significant difference in cardiac survival/hospitalization between patients with and without LVCR. The proportion of echocardiographic responders was 144 (87%) of 166 and 16 (42%) of 38 in the groups with and without LVCR (P < .001), respectively; LVCR showed 90% sensitivity and 87% positive predictive value to prefigure echocardiographic CRT responders. Multivariable analysis identified LVCR and interventricular dyssynchrony as independent predictors of CRT response. The concomitant presence of both factors showed 99% specificity and 83% sensitivity in detecting responders.

CONCLUSION

The presence of LVCR helps in predicting a clinical and echocardiographic CRT response. Concomitant assessment of LVCR and interventricular dyssynchrony accurately stratifies responder and nonresponder patients.

Heart failure patients selection for cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is an established treatment for refractory chronic heart failure (CHF) patients with ventricular dyssynchrony. The patient selection for this therapy remains the basis for response improvement. Various parameters, methods and technology for identification of appropriate patient are under research. The influences of age and gender, disease progress stage such as mild and late stage CHF including right ventricular dysfunction, dyssynchrony and scar identified by imaging techniques like echocardiography, magnetic resonance and nuclear imaging, and atrial fibrillation on CRT benefits were respectively discussed. This review summarizes the current advancement in these areas.

Usefulness of NT-pro BNP monitoring to identify echocardiographic responders following cardiac resynchronization therapy

Background

Cardiac resynchronization therapy (CRT) improves left ventricular (LV) volumes, mitral regurgitation (MR) severity and symptoms of patients with heart failure (HF). However, ≥ 30% of patients have no significant clinical or echocardiographic improvement following CRT. Reverse remodeling after CRT correlates with improved clinical outcomes. We hypothesized that in NT-pro BNP monitoring is accurate to identify responders following CRT.

Methods

42 consecutive patients (mean age 66 ± 12 years, male 68%) with HF undergoing CRT were prospectively enrolled. Responders at follow-up were defined by echocardiography (decrease in LV end systolic volume ≥ 15%). Echocardiography and NT-pro BNP measurement were performed at baseline and repeated 3 to 6 month after CRT.

Results

There was no significant difference between responders (n = 29, 69%) and non-responders (n = 13, 31%) regarding baseline NT-pro BNP level. Responders had significantly higher decrease in NT-pro BNP levels during follow-up than non-responders (absolute: -1428 ± 1333 pg.ml^-1 vs. -61 ± 959 pg.ml^-1, p = 0.002; relative: -45 ± 28% vs. 2 ± 28%, p < 0.0001). A decrease of ≥ 15% in NT-pro BNP 3–6 months after CRT identifies echocardiographic responders with a sensitivity of 90% and a specificity of 77%.

Conclusion

NT-pro BNP monitoring can accurately identify echocardiographic responders after CRT.