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Predictive value of heart rate in dilated cardiomyopathy treated with metoprolol
A Perkan1, A Di Lenarda, G Sinagra
1Divisione di Cardiologia, Ospedale Maggiore, Trieste.
Insights
Higher heart rate predicts better response to metoprolol in dilated cardiomyopathy (DCM) patients. This relationship is non-linear and depends on disease severity, suggesting heart rate is a key factor in treatment success.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Predictive factors for successful beta-blocker therapy in dilated cardiomyopathy (DCM) are not well understood.
- The specific role of heart rate in predicting treatment response remains controversial.
Purpose of the Study:
- To examine the association between heart rate and treatment outcomes in DCM patients receiving chronic metoprolol therapy.
- To determine if heart rate is a reliable predictor of response to metoprolol in DCM.
Main Methods:
- Ninety-eight DCM patients with left ventricular ejection fraction (LVEF) ≤ 0.40 and controlled blood pressure were treated with metoprolol, digitalis, diuretics, and ACE inhibitors.
- Patients were assessed after 24 ± 6 months using a clinical/instrumental score to determine improvement.
- Heart rate parameters (rest, 24-hour, exercise) were analyzed in relation to treatment response.
Main Results:
- Resting, 24-hour, and maximal exercise heart rates were significantly associated with a higher probability of improvement.
- Heart rate at rest (supine and upright) demonstrated the strongest predictive power.
- The heart rate-response relationship was non-linear, with benefits plateauing or decreasing at extreme tachycardia levels, particularly in advanced disease stages.
Conclusions:
- A strong, non-linear relationship exists between heart rate and clinical improvement in DCM patients treated with metoprolol.
- Heart rate is a significant predictor of metoprolol response in DCM, with its influence modulated by disease severity.
Unlabelled:
Predictive factors of a favourable response to beta-blocker therapy are still unknown and the role of heart rate remains controversial.
Aim:
To investigate the relation between heart rate and the response to chronic metoprolol treatment in patients with dilated cardiomyopathy (DCM).
Methods:
Ninety-eight consecutive patients with DCM, left ventricular ejection fraction (LVEF) < or = 0.40 and blood pressure < or = 140/90 mmHg were treated with metoprolol, associated with digitalis, diuretics and ACE-inhibitors. After 24 +/- 6 months, 48 patients (49%) were classified as "improved" on the basis of a clinical/instrumental score.
Results:
Rest, mean 24-hour and maximal exercise heart rate were all significantly and directly related to the probability of improvement, but heart rate at rest, supine and in upright position, showed the highest predictive power. The relationship between heart rate and improvement with metoprolol appeared to be non-linear, with an increasing probability in patients with higher heart rate, but with a fall of the slope in cases with extreme tachycardia. By dividing our study population on the basis of the most important clinical variables, this complex relation was evident only in patients at a more advanced stage of the disease.
Conclusion:
Our analysis confirms the strict relationship between heart rate and improvement with chronic metoprolol therapy in patients with DCM. This relation seems to be non-linear and is influenced by the severity of the disease.