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Relation between contractile reserve and improvement in left ventricular function with beta-blocker therapy in

Frank F Seghatol1, Dipan J Shah, Silvia Diluzio

  • 1Division of Cardiology, Department of Medicine, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA.

The American Journal of Cardiology
|March 31, 2004
PubMed

Insights

Contractile reserve (CR) predicts how well patients with heart failure respond to beta blockers. Patients with ischemic cardiomyopathy show an early response if they have CR, while those with idiopathic dilated cardiomyopathy show a sustained response.

Area of Science:

  • Cardiology
  • Heart Failure Research
  • Pharmacological Interventions

Background:

  • Beta blockers are standard therapy for heart failure, improving left ventricular (LV) ejection fraction.
  • Patient responses to beta blockers are highly variable, necessitating predictors of treatment efficacy.
  • Contractile reserve (CR) is a potential marker for assessing myocardial viability and predicting response to therapy.

Purpose of the Study:

  • To investigate the role of contractile reserve (CR) in predicting beta-blocker response in patients with ischemic cardiomyopathy (IC) and idiopathic dilated cardiomyopathy (IDC).
  • To compare the time course and magnitude of left ventricular function improvement based on CR status in different cardiomyopathy types.

Main Methods:

  • Echocardiograms (resting and dobutamine) were performed on 32 heart failure patients (LV ejection fraction ≤35%).
  • Patients were categorized into ischemic cardiomyopathy (IC) and idiopathic dilated cardiomyopathy (IDC) groups.
  • Contractile reserve (CR) status was determined by dobutamine stress echocardiography, and patients were classified as CR-positive (CR+) or CR-negative (CR-).
  • Left ventricular function was assessed at baseline and 2, 6, and 14 months after initiating beta-blocker therapy, measuring improved contractility segments, ejection fraction, and wall motion score index.

Main Results:

  • In the IC group, CR+ patients showed significantly greater improvement in contractility segments at 2 and 6 months compared to CR- patients.
  • In the IDC group, CR+ patients demonstrated significantly greater improvement in contractility segments at all time points (2, 6, and 14 months) compared to CR- patients.
  • Similar trends were observed for ejection fraction and wall motion score index, indicating that CR status influences the degree and duration of LV function improvement.

Conclusions:

  • Contractile reserve status is a significant predictor of the time course and magnitude of left ventricular functional improvement in heart failure patients treated with beta blockers.
  • CR predicts a more rapid early response in ischemic cardiomyopathy and a sustained response in idiopathic dilated cardiomyopathy.
  • Even patients without detectable contractile reserve demonstrated some improvement in LV function over 14 months, suggesting other mechanisms of recovery or adaptation.

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