Acetazolamide and inhaled carbon dioxide reduce periodic breathing during exercise in patients with chronic heart failure.

BACKGROUND: Periodic breathing (PB) during sleep and exercise in heart failure (HF) is related to respiratory acid-base status, CO2 chemosensitivity, and temporal dynamics of CO2 and O2 sensing. We studied inhaled CO2 and acetazolamide to alter these factors and reduce PB. METHODS AND RESULTS: We measured expired and arterial gases and PB amplitude and duration in 20 HF patients during exercise before and after acetazolamide given acutely (500 mg intravenously) and prolonged (24 hours, 2 g orally), and we performed overnight polysomnography. We studied CO2 inhalation (1%-2%) during constant workload exercise. PB disappeared in 19/20 and 2/7 patients during 2% and 1% CO2. No changes in cardiorespiratory parameters were observed after acute acetazolamide. With prolonged acetazolamide at rest: ventilation +2.04 ± 4.0 L/min (P = .001), tidal volume +0.11 ± 1.13 L (P = .003), respiratory rate +1.24 ± 4.63 breaths/min (NS), end-tidal PO2 +4.62 ± 2.43 mm Hg (P = .001), and end-tidal PCO2 -2.59 ± 9.7 mm Hg (P < .001). At maximum exercise: Watts -10% (P < .02), VO2 -61 ± 109 mL/min (P = .04) and VCO2 101 ± 151 mL/min (P < .02). Among 20 patients, PB disappeared in 1 and 7 subjects after acute and prolonged acetazolamide, respectively. PB was present 80% ± 26, 65% ± 28, and 43% ± 39 of exercise time before and after acute and prolonged acetazolamide, respectively. Overnight apnea/hypopnea index decreased from 30.8 ± 83.8 to 21.1 ± 16.9 (P = .003). CONCLUSIONS: In HF, inhaled CO2 and acetazolamide reduce exercise PB with additional benefits of acetazolamide on sleep PB.

Can ß-blockers influence regular daily physical activity?

BACKGROUND: In hypertension, ß-blockers have a high rate of nonadherence to treatment likely because of fatigue. METHODS: We evaluate daily physical activity and maximal exercise performance in 56 patients with hypertension (grades I-II), with and without ß-blockers (bisoprolol 10 mg or atenolol 100 mg) added to standard treatment; 48 patients completed the study. Study tests were performed after 8 weeks of antihypertensive therapy without ß blockers and after the following 8 weeks with ß-blockers. RESULTS: No significant differences between ß-blockers were observed. At office measurement, ß-blockers decreased heart rate (HR) from 78 ±â€Š9 to 62 ±â€Š7 bpm (P < 0.01) and SBP from 133 ±â€Š13 to 125 ±â€Š12 mmHg (P < 0.01). No significant changes were observed for DBP. Conversely, at ambulatory pressure monitoring DBP but not SBP decreased with ß-blockers (mean-24-h DBP 77 ±â€Š8 vs. 74 ±â€Š7 mmHg, P < 0.01). An overall reduction of daily activities and of estimated kilocalories consumption was observed as measured by a portable armband device. Of note, time with activity more than 3 METS was reduced by ß-blockers from 148.1 (83-201) to 117.9 (82-189) min (P < 0.01). Cardiopulmonary exercise (CPE) showed a preserved exercise performance unaffected by ß-blockers. CONCLUSION: In hypertension, ß-blocker treatment is associated to reduction of daily physical activity but not of maximal exercise performance.

Effects of beta-blockers on ventilation efficiency in heart failure.

BACKGROUND: Hyperventilation and consequent reduction of ventilation (VE) efficiency are frequently observed during exercise in heart failure (HF) patients, resulting in an increased slope of VE/carbon dioxide (VE/Vco(2)) relationship. The latter is an independent predictor of HF prognosis. beta-Blockers improve the prognosis of HF patients. We evaluated the effect on the efficiency of VE of a beta(1)-beta(2) unselective (carvedilol) versus a beta(1) selective (bisoprolol) beta-blocker. METHODS: We analyzed consecutive maximal cardiopulmonary exercise tests performed on 572 clinically stable HF patients (New York Heart Association class I-III, left ventricle ejection fraction < or =50%) categorized in 3 groups: 81 were not treated with beta-blocker, 304 were treated with carvedilol, and 187 were treated with bisoprolol. Clinical conditions were similar. RESULTS: The VE/Vco(2) slope was lower in carvedilol- compared with bisoprolol-treated patients (29.7 +/- 0.4 vs 31.6 +/- 0.5, P = .023, peak oxygen consumption adjusted) and with patients not receiving beta-blockers (31.6 +/- 0.7, P = .036). Maximum end-tidal CO(2) pressure during the isocapnic buffering period was higher in patients treated with carvedilol (39.0 +/- 0.3 mm Hg) than with bisoprolol (37.2 +/- 0.4 mm Hg, P < .001) and in patients not receiving beta-blockers (37.2 +/- 0.5 mm Hg, P = .001). CONCLUSIONS: Reduction of hyperventilation, with improvement of VE efficiency during exercise (reduction of VE/Vco(2) slope and increase of maximum end-tidal CO(2) pressure), is specific to carvedilol (beta(1)-beta(2) unselective blocker) and not to bisoprolol (beta(1)-selective blocker).

Comparison of the diagnostic performance of 64-slice computed tomography coronary angiography in diabetic and non-diabetic patients with suspected coronary artery disease.

BACKGROUND: Diabetics have high prevalence of subclinical coronary artery disease (CAD) with typical characteristics (diffuse disease, large calcifications). Although 64-slice multidetector computed tomography (MDCT) coronary angiography has high diagnostic accuracy to detect CAD, its diagnostic performance in diabetics with suspected CAD is unknown. To compare the diagnostic performance of 64-slice MDCT between diabetics and non-diabetics with suspected CAD scheduled for invasive coronary angiography (ICA). METHODS: We enrolled one hundred and five diabetic patients (92 men, age 65 +/- 9 years, Group 1) and 105 non-diabetic patients (63 men, age 63+/-5 years, Group 2) with indication to ICA for suspected CAD undergoing coronary 64-slice MDCT before ICA. RESULTS: In Group 1, the overall feasibility of coronary artery visualization was 93.8%. The most frequent artifact was blooming due to large coronary calcifications (54 artifacts, 67%). In Group 2, the overall feasibility was significantly higher vs. Group 1 (97%, p < 0.0001). In Group 1, the segment-based analysis showed a MDCT sensibility, specificity, positive predictive value, negative predictive value and accuracy for the detection of ≥50% luminal narrowing of 77%, 90%, 70%, 93% and 87%, respectively. In Group 2, all these parameters were significantly higher vs. Group 1. In the patient-based analysis, specificity, negative predictive value and accuracy were significantly lower in Group 1 vs. Group 2. CONCLUSIONS: Although MDCT has high sensitivity for early identification of significant CAD in diabetics, its diagnostic performance is significantly reduced in these patients as compared to non-diabetics with similar clinical characteristics.

Influence of exertional oscillatory ventilation on exercise performance in heart failure.

BACKGROUND: Exertional oscillatory ventilation (EOV) in heart failure may potentiate the negative effects of low cardiac output and high ventilation on exercise performance. We hypothesized that the presence of EOV might, per se, influence exercise capacity as evaluated by maximal cardiopulmonary exercise test. METHODS AND RESULTS: We identified 78 severe chronic heart failure patient pairs with and without EOV. Patients were matched for sex, age and peak oxygen consumption (VO2). Patients with EOV showed, for the same peak VO2, a lower workload (WL) at peak (DeltaWatts=5.8+/-23.0, P=0.027), a less efficient ventilation (higher VE/VCO2 slope: 38.0+/-8.3 vs. 32.8+/-6.3, P<0.001), lower peak exercise tidal volume (1.49+/-0.36 L vs. 1.61+/-0.46 L, P=0.015) and higher peak respiratory rate (34+/-7/min vs. 31+/-6/min, P=0.002). In 33 patients, EOV disappeared during exercise, whereas in 45 patients EOV persisted. Fifty percent of EOV disappearing patients had an increase in the VO2/WL relationship after EOV regression, consistent with a more efficient oxygen delivery to muscles. No cardiopulmonary exercise test parameter was associated with the different behaviour of VO2/WL. CONCLUSION: The presence of EOV negatively influences exercise performance of chronic heart failure patients likely because of an increased cost of breathing. EOV disappearance during exercise is associated with a more efficient oxygen delivery in several cases.

The metabolic exercise test data combined with Cardiac And Kidney Indexes (MECKI) score and prognosis in heart failure. A validation study.

BACKGROUND: The Metabolic Exercise test data combined with Cardiac and Kidney Indexes (MECKI) score is a prognostic model to identify heart failure (HF) patients at risk for cardiovascular mortality (CVM) and urgent heart transplantation (uHT) based on 6 routine clinical parameters: hemoglobin, sodium, kidney function by the Modification of Diet in Renal Disease (MDRD) equation, left ventricle ejection fraction (LVEF), percentage of predicted peak oxygen consumption (VO2) and VE/VCO2 slope. OBJECTIVES: MECKI score must be generalizable to be considered useful: therefore, its performance was validated in a new sequence of HF patients. METHODS: Both the development (MECKI-D) and the validation (MECKI-V) cohorts were composed of consecutive HF patients with LVEF <40% able to perform a symptom-limited cardiopulmonary exercise testing. The CVM or uHT rates were analyzed at one, two and three years in both cohorts: all patients with a censoring time shorter than the scheduled follow-up were excluded, while those with events occurring after 1, 2 and 3 years were considered as censored. RESULTS: MECKI-D and MECKI-V consisted of 2009 and 992 patients, respectively. MECKI-V patients had a higher LVEF, higher peak VO2 and lower VE/VCO2 slope, higher prescription of beta-blockers and device therapy: after the 3-year follow-up, CVM or uHT occurred in 206 (18%) MECKI-D and 44 (13%) MECKI-V patients (p<0.000), respectively. MECKI-V AUC values at one, two and three years were 0.81 ± 0.04, 0.76 ± 0.04, and 0.80 ± 0.03, respectively, not significantly different from MECKI-D. CONCLUSIONS: MECKI score preserves its predictive ability in a HF population at a lower risk.

A long-term prognostic value of coronary CT angiography in suspected coronary artery disease.

OBJECTIVES: The aim of this study was to assess the long-term prognostic role of multidetector computed tomography coronary angiography (CTA) in patients with suspected coronary artery disease (CAD). BACKGROUND: Use of CTA is increasing in patients with suspected CAD. Although there is a large body of data supporting the prognostic role of CTA for major adverse cardiac events in the intermediate term, its long-term prognostic role in patients with suspected CAD is not well studied. METHODS: Between February 2005 and March 2008, 1,304 consecutive patients were prospectively studied with CTA for detecting the presence and assessing extent of CAD (disease extension and coronary plaque scores). Patients were classified according to the presence of normal coronaries and nonobstructive (<50%) and obstructive (>50%) coronary lesions. The composite rates of hard cardiac events (cardiac deaths and nonfatal myocardial infarctions) and all cardiac events (including late revascularization) were the endpoints of the study. RESULTS: Seventy patients were excluded because their CTA data were uninterpretable. Of the remaining 1,234 patients, clinical follow-up (mean 52 ± 22 months) was obtained for 1,196 (97%). A total of 475 events were recorded, with 136 hard events (18 cardiac deaths and 118 nonfatal myocardial infarctions) and 123 late revascularizations. A total of 216 patients with early elective revascularizations were excluded from the survival analysis. Significant independent predictors of events in multivariate analysis were multivessel disease and left main CAD. Cumulative event-free survival was 100% for hard and all events in patients with normal coronary arteries, 88% for hard events and 72% for all events in patients with nonobstructive CAD, and 54% for hard events and 31% for all events in patients with obstructive CAD. Multivessel CAD was associated with a higher rate of hard cardiac events. CONCLUSIONS: CTA provides prognostic information in patients with suspected CAD and unknown cardiac disease, showing excellent long-term prognosis when there is no evidence of atherosclerosis and allowing risk stratification when CAD is present.