Kazuhiko Tanabe

Plasma brain natriuretic peptide concentrations and the risk of cardiovascular events and death in general practice

OBJECTIVES The plasma brain natriuretic peptide concentrations (brain natriuretic peptide (BNP) levels) have a prognostic value of mortality and morbidity in patients with chronic heart failure and in a community-based population. However, the prognostic value of BNP levels in outpatients of general practice is not well known. This study investigated the relations of BNP levels to cardiovascular events and death in general practice. METHODS This study covered 3123 consecutive outpatients (mean age 59.3±15.3 years; 42% men). BNP levels were measured by immunoradiometric assay (Shionogi) in an occasional sample of each person. RESULTS During a median follow-up of 5.5 years, 271 patients underwent a cardiovascular event (heart failure 65, coronary heart disease events 63, arrhythmia 26, stroke 96, others 21), 92 died from cardiovascular disease and 227 died from all causes. The patients were stratified into two groups based on a cut-off level of BNP (100 pg/ml). A BNP level ≥100 pg/ml was associated with a hazard ratio (95% confidence interval) of 4.6 (3.5-6.1) for cardiovascular events compared with a BNP <100 pg/ml (p<0.0001), 7.0 (4.5-10.9) for cardiovascular mortality (p<0.0001), 3.2 (2.4-4.2) for all-cause mortality (p<0.0001), 18.8 (11.3-31.1) for heart failure (p<0.0001), 2.5 (1.5-3.9) for stroke (p=0.0002), 5.0 (2.4-11.2) for atrial fibrillation (p<0.0001); however, it was 0.6 (0.2-1.7) for coronary heart disease events (p=0.337). Furthermore, the result of investigation with stratification into six groups based on BNP cut-off levels (20, 40, 100, 200, 500 pg/ml) showed that cardiovascular events, cardiovascular mortality, all-cause mortality, heart failure, stroke, and atrial fibrillation increased stepwise as BNP levels increased (p<0.0001), except for coronary heart disease events (p=0.986). CONCLUSIONS In general practice, BNP levels predicted the risk of cardiovascular events other than coronary heart disease events and of death.

Magnesium Content of Erythrocytes in Patients with Vasospastic Angina

SummaryThe possibility that a magnesium deficiency might be the underlying cause of vasospastic angina (VA) and the efficacy of Mg administration in its treatment were studied. Subjects included 15 patients with VA and 18 healthy subjects as the control group. The erythrocyte Mg content was measured by atomic absorption, and serum Mg was measured by conventional chemical assay. The efficacy of Mg administration was studied in seven patients with VA. The results were as follows: a) The mean erythrocyte Mg content was less in the group with frequent episodes of angina (1.59 ± 0.11 mg/ dl) than in the group without angina (2.11 ± 0.38 mg/dl, p < 0.01) and in the control group (2.22 ± 0.29 mg/dl, p < 0.01). There was no significant difference between the control group and patients of each group with respect to serum Mg. b) Coronary arterial spasm was induced by ergonovine maleate in seven patients and was completely inhibited by the administration of Mg sulfate (40–80 mEq, hourly) in six of these patients; in the remaining patient neither obvious ST change nor chest pain occurred. Thus, it was concluded that the measurement of erythrocyte Mg content is useful to determine how easily vasospasm might occur in VA and that the administration of Mg might be developed as a new therapy for spasm associated with a low erythrocyte Mg content.

Cardiopulmonary responses at various angles of cycle backrest inclination.

The purpose of this study was to evaluate cardiopulmonary responses during submaximal cycle exercise at various angles of backrest inclination. Ten healthy Japanese men of mean age 25.9 yrs, height 170.6 cm, and body mass 66.1 kg, performed cycle exercises at a constant workload which reached the anaerobic threshold, at 20 degrees, 40 degrees, and 60 degrees of backrest inclination from the vertical plane, but the angle between the seat and back rest was kept at 110 degrees. The results were as follows: 1) Both cardiac output and stroke volume showed a higher value at the resting control state and during exercise as the backrest angle increased. 2) Oxygen consumption, carbon dioxide output, heart rate, gas exchange ratio, and oxygen pulse were not affected by the angle of backrest inclination. 3) Tidal volume at 20 degrees of backrest inclination was higher than at 60 degrees. 4) No significant differences were found in minute ventilation between each backrest angle. These findings suggest that changes in the backrest angle significantly alter cardiopulmonary parameters at rest and during exercise; in particular, an angle difference of 40 degrees may be enough to alter tidal volume, cardiac output and stroke volume, but not the minute ventilation.

The Effects of Posture on the Ventilatory Responses During Exercise.

This study was undertaken to evaluate the postural effect on ventilatory responses during both supine and sitting exercise. Seven healthy men performed two exercise tests utilizing the ramp protocol (20 watts/min) with a cycle ergometer in each position. The results were as follows: The oxygen uptake and the oxygen pulse measured at 180 watts and at anaerobic threshold in the sitting were significantly higher compared with those in the supine position. The average of carbon-dioxide output, minute ventilation and tidal volume at lower exercise intensities showed higher values in the sitting compared with those in the supine position, whereas there were no significant differences for respiratory rate. There was significant difference in the slope of the minute ventilation to carbon-dioxide output plot between sitting and supine position. In conclusion, the higher minute ventilation in the sitting position was mainly performed by higher tidal volume which may counteract the effects of an increase in physiological dead space. The lower slope of the minute ventilation to carbon-dioxide output plot which shows more effective ventilation in the supine position may be due to decreased physiological dead space and higher diffusion capacity.

Brain Natriuretic Peptide and the Risk of Cardiovascular Events and Death in Patients with Atrial Fibrillation

Brain natriuretic peptide (BNP) is a hormone that is secreted by the heart, especially from the ventricle (Sudoh et al., 1988; Yasue et al., 1994). The plasma BNP concentrations (BNP levels) are correlated positively with the left ventricular end-diastolic pressure and negatively with the left ventricular ejection fraction (Yoshimura et al., 1993; Maeda et al., 1998), so BNP levels should be measured to evaluate left ventricular function. BNP levels have proved to be good markers of congestive heart failure. In addition, BNP levels are useful in screening test for left ventricular dysfunction and also heart disease. Some studies have shown that BNP levels have a prognostic value of mortality and morbidity in patients with chronic heart failure (Maeda et al., 2000; Anand et al., 2003), in general populations (Wang et al., 2004) and in clinical practice (Tsuchida & Tanabe, 2008). However, the prognostic value of BNP levels in patients with atrial fibrillation (AF) is not well known. This study investigated the relations of BNP levels to cardiovascular events and death in patients with AF. Hohnloser et al. suggested that warfarin therapy was needed in patients with paroxysmal AF similarly as in those with sustained AF (Hohnloser et al., 2007). Another report showed that, if sinus rhythm was maintained with antiarrhythmic therapy, the prognosis of the patients with paroxsmal AF for ischemic stroke was better than those with permanent AF (Komatsu et al., 2004). We examined the necessity of warfarin therapy in patients with paroxysmal AF as in those with chronic AF. Furthermore, CHADS2 score is known to be very useful to decide the indication of warfarin therapy in patients with AF (Gage et al., 2001). The patients with CHADS2 score of 2 or more are recommended to take warfarin therapy, those with CHADS2 score of 1 to take Warfarin or antiplatelet drugs, and those with CHADS2 score of 0 need not any take warfarin. We investigated the usefulness of BNP as an aid in CHADS2 score to decide the indication of warfarin therapy in patients with CHADS2 score of 0 or 1.