| Purpose1. To analyze the characters of some parameters of cardiac function and ventricular volume in chronic heart failure (CHF).2. To observe the effects of different initial dosage of metoprolol on cardiac function.3. To discuss the benefits of long-term treatment with metoprolol in patients (pts) with CHF.MethodsThirty-one pts were enrolled. All pts wear with NYHA function II-IV and left ventricular ejection fraction (LVEF) 0.45 or less (classII in 10 pts, class III in 13 pts and class IV in 8 pts). An acute trial with metoprolol was performed in all pts. According to initial dosage,12 pts were assigned to low-dose (6.25mg) group, and 19 pts were assigned to higher-dose (12.5mg) group. After acute trial, 27 pts accepted long-term therapy trial. Eighteen pts were randomly assigned to long-term treatment with metoprolol and 9 patients were assigned to standard therapy without metoprolol. The dose of metoprolol was titrated from the small initial dosage to the highest tolerated dosage. All of the 27 patients were followed up for 3-6 months. Thirteen healthy volunteers were enrolled as controls. Theparameters of cardiac function and ventricular volume were collected by gated single-photon emission computed tomography system ( ADAC Co.). At the same time, the base data including heart rate, blood pressure were collected. The heart rate (HR), systolic blood pressure (SBP), left ventricular ejection fraction (LVEF), end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), cardiac output (CO), and cardiac index (CI) were collected before and after the treatment with metoprolol. Results1. The LVEF for the pts with CHF and controls was 29.1 ± 12.1% and 63.7 ± 4.6% respectively (P<0.01). The parameters reflecting cardiac work for pts/controls were as following: HR(84.9 ±16.8/73.2 ± 6.0, P<0.05), CI(2409 ± 565ml/min/m2/2078 ± 221ml/min/m2, P<0.05), SBP×HR(10266 ± 2274/8535 ± 1587, P<0.05).2. Following the administration of the metoprolol in acute trial, the HR was from 91.2 ±16.4 to 83.5± 16.4 (P<0.01) and HR×SBP was from 10308 ±2180 to 9358 ± 1845 (P<0.01) in low-dose group (6.25mg). The LVEF was from 32.6 ± 12.1% to 29.5± 11.3% (P< 0.01), HR was from 80.9±16.3 to 74.4±14.7 (P<0.01), SBP was from 127.3 ±18.4mmHg to 123.4±21.8mmHg (P<0.05), SV was from 51.8± 15.7ml to 47.4± 13.9ml (P<0.05), CO was from 4088 ± 1062ml/min to 3437±857ml/min (P<0.01), and CI was from2320 + 596 ml/min/m2 to 1962 + 565 ml/min/m2 (P<0.01) in the higher-dose group.3. Long-term treatment trial with metoprolol: Twenty-five of 27 pts completed the study (16 of long-term group with metoprolol, 9 of controlled group without metoprolol). No changes of the parameters were observed in the controlled group. After the long-term treatment with metoprolol, the cardiac function was significantly improved: an increase of LVEF(from (29.2+11.9)% to (36.1 + 12.2)%, P<0.01), and a decrease in EDV(from 195.9 +97.5ml to 161.8 +72.5ml , P <0.05), ESV(from 147.1 +97.1ml to 109.9 +70.2ml, P<0.05), HR(from 87.2+17.4 to 73.0+13.8, P<0.01), SBPXHR (from 11064+2435 to 8982+ 1812 , P<0.01). CI was reduced and closed to normal level, but there was no statistical significance. Conclusions1. There is a "cardiac function over-compensation" phenomenon in some pts with heart failure. It may be the objective basis of the treatment with fl -blocking agents in CHF patients.2. For the pts with CHF, P -blockers, such as metoprolol, may induce a negative chronotropic and inotropic effects. But the effects can be avoided by suitable initial dosage. An appropriate initial therapy could reduce the cardiac oxygen consumption and cardiac work. So P -blockers could be started earlier in some CHF patients.The principles for choice of the initial dose were discussed fortreatment of CHF.3. The benefits following long-term treatment with β -blockingagents for CHF were improvement of symptoms, reversion ofmyocardial remodeling and improvement of cardiac...
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