Valter Bianchi

Effects of converting enzyme inhibition on heart period variability in patients with acute myocardial infarction.

Heart period variability provides useful prognosticinformation on autonomic cardiac control, and a strong association has been demonstrated after myocardial infarction (MI) between cardiac mortality, sudden death, and reduced total power, ultralow-frequency (ULF) power, and very-lowfrequency (VLF) power. Converting enzyme inhibitors are widely used in MI patients, but their influence on heart period variability emains to be defined. Methods and ResultsTime- and frequency-domain measures of heart period variability were calculated from 24-hour Holter monitoring in 40 patients with a first uncomplicated MI. After baseline examination between 48 and 72 hours after symptom onset, patients were randomly assigned to placebo or captopril administration, and on the third day, 24- hour Holter monitoring was repeated. No changes in time and frequency domain were detectable after placebo. After captopril, the SD of all normal RR (NN) intervals (SDNN) increased from 90±29 to 105±30 milliseconds (P < .01); the SD of the average NN intervals for all 5-minute segments (SDANN index) and the mean of the SDs of all NN intervals for all 5-minute segments (SDNN index) also increased from 74±24 to 90±26 milliseconds (P < .01) and from 45±17 to 49±15 milliseconds (P < .05), respectively. The root mean square successive difference (r-MSSD) and the percent of differences between adjacent NN intervals >50 milliseconds (pNN50) remained unchanged. In regard to frequency-domain measures, after captopril, total power (ln unit) increased from 8.28±0.42 to 8.47±0.30 (P < .01); considering the frequency bands, a significant increase was observed in ULF (P < .01), VLF (P < .05), and low-frequency (LF) power (P < .05), whereas high-frequency (HF) power remained unchanged. ConclusionsThis study supports the hypothesis that the renin-angiotensin system modulates the amplitude of ULF and VLF power. Furthermore, it demonstrates that in MI patients, converting enzyme inhibition favorably modifies measures of heart period variability strongly associated with a poor prognosis.

Power spectral analysis of heart period variability in hypertensive patients with left ventricular hypertrophy.

This study aimed to characterize sympathovagal balance by heart period power spectrum analysis in hypertensive patients with echocardiographic evidence of left ventricular hypertrophy. Twenty ambulatory patients (11 men and 9 women), aged 50 +/- 10 years, with established essential hypertension and echocardiographic left ventricular hypertrophy, performed 24-h blood pressure monitoring and electrocardiogram Holter recording on 2 consecutive days. Twenty age- and sex-matched normal subjects comprised the control group. Power spectrum analysis, performed using the fast Fourier transform algorithm, demonstrated lower values of low and high frequency power in hypertensives than in controls, while ultralow and very low frequency power were similar in the two groups. Very low frequency, low frequency, and high frequency power increased during the night in both groups, showing a similar circadian pattern. We found a direct correlation between daytime systolic (r = 0.51; P < .05) and diastolic (r = 0.52; P < .05) blood pressure and left ventricular mass index. Moreover, negative correlations were found between left ventricular mass index and low frequency (r = -0.47; P < .05) and high frequency power (r = -0.47; P < .05). There was a direct correlation between nighttime decrease in systolic blood pressure and nighttime increase in high frequency power (r = 0.45; P < .05). As 24-h low frequency and high frequency power, obtained using the Fourier transform algorithm, both reflect the parasympathetic modulation of heart rate, our results demonstrate that hypertensive patients with left ventricular hypertrophy are characterized by a sympathovagal imbalance with a reduction of vagal tone that is more evident with increasing severity of hypertension.

Effects of captopril treatment on left ventricular remodeling and function after anterior myocardial infarction: comparison with digitalis.

The effects of captopril and digoxin treatment on left ventricular remodeling and function after anterior myocardial infarction were evaluated in a randomized unblinded trial. Fifty-two patients with a first transmural anterior myocardial infarction and a radionuclide left ventricular ejection fraction less than 40% were randomly assigned to treatment with captopril (Group A) or digoxin (Group B). The two groups had similar baseline hemodynamic, coronary angiographic, echocardiographic and radionuclide angiographic variables. Among the 40 patients (20 in each group) who were followed up for 1 year, echocardiographic end-diastolic and end-systolic volumes were unmodified in Group A and global wall motion index was improved (p less than 0.01); in Group B, end-diastolic and end-systolic volumes increased (p less than 0.001 for both) and global wall motion index was unchanged. Rest radionuclide ejection fraction increased significantly in both groups (p less than 0.001, Group A; p less than 0.005, Group B). A comparison of the changes in the considered variables between the two groups after 1 year of treatment showed a difference in end-diastolic (p less than 0.005) end-systolic volumes (p less than 0.001) and global wall motion index (p less than 0.005) without differences in radionuclide ejection fraction, which improved to a similar degree in both groups. The results of this study suggest that captopril therapy, started 7 to 10 days after symptom onset in patients with anterior myocardial infarction and an ejection fraction less than 40%, improves both left ventricular remodeling and function and prevents left ventricular enlargement and in these patients performs better than digitalis.

Characterization and prognostic significance of silent myocardial ischemia on predischarge electrocardiographic monitoring in unselected patients with myocardial infarction

Characteristics and prognostic significance of ischemic ST changes at predischarge Holter monitoring were evaluated in 270 consecutive postinfarction patients. The 64 patients with ST changes had a greater incidence of non-Q-wave myocardial infarction (p less than 0.01) and ventricular premature contractions (p less than 0.01); they were more frequently in Moss class greater than 2 (p less than 0.01) and they had a lower wall motion score (p less than 0.05). At 2-year follow-up, patients with ST changes had a higher incidence of cardiac death and reinfarction. At multivariate analysis, Killip class (p less than 0.01) and ST changes (p less than 0.05) were the most predictive variables; when multivariate analysis was repeated including an additional variable--the inability to perform a stress test--Killip class was the most significant variable (p less than 0.01), and the presence of ST changes showed only borderline statistical significance (p less than 0.1). In the subset of patients who did not perform the stress test, ST change was the most important variable (p less than 0.01), followed by Killip class (p less than 0.05). Thus, after myocardial infarction, ST changes during Holter monitoring are associated with a poor prognosis and appear useful for stratifying patients who do not perform exercise stress tests.

Effect of 1 Year of Lisinopril Treatment on Cardiac Autonomic Control in Hypertensive Patients With Left Ventricular Hypertrophy

In this study we evaluated in hypertensive patients the effects of drug-induced left ventricular hypertrophy regression on cardiac autonomic control, as assessed by means of heart period variability analysis. Power spectral analysis of 24-hour electrocardiographic monitoring was performed in 30 hypertensive patients with left ventricular hypertrophy at baseline, after 1 year of lisinopril treatment, and after 1 month of drug withdrawal. At the same times, patients underwent 24-hour blood pressure monitoring, echocardiographic study, and plasma renin activity assessment. Lisinopril treatment increased plasma renin activity and reduced 24-hour systolic and diastolic pressures (from 159 +/- 14 to 121 +/- 8 and from 103 +/- 7 to 80 +/- 3 mm Hg, respectively) and left ventricular mass index (from 159 +/- 33 to 134 +/- 26 g/m2); moreover, in 12 of 30 patients, left ventricular mass normalization was achieved. Drug withdrawal was followed by an increase in blood pressure without left ventricular mass modification. In the total study population, only high-frequency power was higher after lisinopril treatment. In the subgroup of patients with left ventricular mass normalization, daytime and nighttime high-frequency powers as well as nighttime total and very-low-frequency powers were higher after 1 year of treatment than at baseline. In the remaining 18 patients, power spectral measures after treatment were slightly lower than at baseline and were even lower after drug withdrawal. Thus, in hypertensive hypertrophic patients, lisinopril treatment improves sympathovagal imbalance when left ventricular mass normalization is achieved. In patients without left ventricular mass normalization, drug withdrawal is followed by a worsening of neural cardiac control.

Influence of reversible segmental left ventricular dysfunction on heart period variability in patients with one-vessel coronary aetery disease

OBJECTIVES This study evaluated the relation between reversible segmental left ventricular dysfunction and frequency domain measures of heart period variability in patients with coronary artery disease. BACKGROUND Heart period variability is frequently reduced in patients with coronary artery disease. However, the mechanisms of this reduction are still unclear. METHODS Echocardiographic left ventricular wall motion and frequency domain measures of heart period variability were evaluated in 32 patients with one-vessel coronary artery disease before and 16 to 24 days after successful percutaneous transluminal coronary angioplasty. Of these, 12 patients (Group A) had normal and 20 patients (Group B) had abnormal regional wall motion. A control group of 15 healthy subjects (Group C) underwent 24-h Holter recording twice at 2-week intervals to check for spontaneous variations. RESULTS At baseline, low and high frequency power were lower in Group B than in Groups A and C, whereas no difference was detectable in ultra low and very low frequency and total power. After coronary angioplasty, regional wall motion and frequency domain measures of heart period variability were unchanged in Group A. In Group B the mean (+/- SD) summed segment score improved from 17.1 +/- 3.6 to 12.8 +/- 2.0 (p < 0.01), and mean low and high frequency power (logarithmic units) increased from 6.14 +/- 0.23 to 6.35 +/- 0.34 (p < 0.01) and from 5.43 +/- 0.32 to 5.68 +/- 0.52 (p < 0.01), respectively. Furthermore, low and high frequency power, lower at baseline in Group B than in the other two groups, were comparable in the three groups after coronary angioplasty. CONCLUSIONS This study demonstrates that segmental left ventricular dysfunction is involved in determining sympathovagal imbalance in patients with one-vessel coronary artery disease; the reversal of left ventricular dysfunction by successful coronary angioplasty improves the heart period power spectrum. Thus, alterations in cardiac geometry influence the discharge of afferent sympathetic mechanoreceptors, contributing to the derangement in autonomic control of heart rate.

Effects of converting enzyme inhibition on baroreflex sensitivity in patients with myocardial infarction.

BACKGROUND Baroreflex sensitivity provides useful prognostic information in patients after acute myocardial infarction. However, no data are available about the effects of converting enzyme inhibition on this variable. OBJECTIVES The aim of the study was to evaluate the effects of angiotensin-converting enzyme inhibition on baroreflex sensitivity in patients after uncomplicated myocardial infarction. METHODS Twenty-five patients after uncomplicated myocardial infarction underwent baroreflex sensitivity evaluation 72 to 96 h after symptom onset and after 4 days of captopril therapy. Twenty additional patients with the same characteristics were evaluated at the same time intervals before and after placebo administration to identify spontaneous baroreflex sensitivity variations. Baroreflex sensitivity was assessed by calculating the regression line relating phenylephrine-induced increases in systolic blood pressure to the attendant changes in the RR interval. RESULTS The mean baroreflex sensitivity value increased after captopril administration from 6.5 +/- 4.2 to 11.8 +/- 6.1 ms/mm Hg (p less than 0.01) and in individual analyses increased by greater than 2 ms/mm Hg in 68% of patients. Mean plasma renin activity increased after captopril from 3.7 +/- 2.4 to 8.5 +/- 4.9 ng/ml per h (p less than 0.005). No difference was detectable in baroreflex sensitivity and plasma renin activity values according to the site of necrosis. In the control group, baroreflex sensitivity and plasma renin activity remained unchanged between the two studies. CONCLUSIONS This study demonstrates that in patients with uncomplicated myocardial infarction, captopril significantly improves the chronotropic response to baroreceptor stimulation.

Changes in electrical activation modify the orientation of left ventricular flow momentum: novel observations using echocardiographic particle image velocimetry

AIMS Changes in electrical activation sequence are known to affect the timing of cardiac mechanical events. We aim to demonstrate that these also modify global properties of the intraventricular blood flow pattern. We also explore whether such global changes present a relationship with clinical outcome. METHODS AND RESULTS We investigated 30 heart failure patients followed up after cardiac resynchronization therapy (CRT). All subjects underwent echocardiography before implant and at follow-up after 6+ months. Left ventricular mechanics was investigated at follow-up during active CRT and was repeated after a temporary interruption <5 min later. Strain analysis, performed by speckle tracking, was used to assess the entity of contraction (global longitudinal strain) and its synchronicity (standard deviation of time to peak of radial strain). Intraventricular fluid dynamics, by echographic particle image velocimetry, was used to evaluate the directional distribution of global momentum associated with blood motion. The discontinuation of CRT pacing reflects into a reduction of deformation synchrony and into the deviation of blood flow momentum from the base-apex orientation with the development of transversal flow-mediated haemodynamic forces. The deviation of flow momentum presents a significant correlation with the degree of volumetric reduction after CRT. CONCLUSION Changes in electrical activation alter the orientation of blood flow momentum. The long-term CRT outcome correlates with the degree of re-alignment of haemodynamic forces. These preliminary results suggest that flow orientation could be used for optimizing the biventricular pacing setting. However, larger prospective studies are needed to confirm this hypothesis.

Continuous electrocardiographic monitoring for more than one hour does not improve the prognostic value of ventricular arrhythmias in survivors of first acute myocardial infarction

This study was designed to compare the prognostic value of predischarge ambulatory electrocardiographic monitoring for 1, 6 and 24 hours in 188 patients surviving a first acute myocardial infarction. Ventricular premature complexes (VPCs) were considered as a mean hourly rate or classified using Lown and Moss grading systems. During the 1-year follow-up 20 cardiac deaths occurred. For all 3 monitoring times, a higher number of VPCs/hour and a higher Moss grade were associated with mortality, whereas a Lown grading system gave prognostic information only for the first hour of recording. Monitoring time did not influence specificity or sensitivity in predicting mortality; > or = 3 VPCs/hour showed a higher sensitivity than > or = 10 VPCs/hour (p < 0.05) with a comparable specificity. After 1-hour data entered the model, neither the 6- or the 24-hour data entry improved the overall likelihood ratio statistic, regardless of what VPC grading system was used. These results demonstrate that continuous electrocardiographic recordings of > 1 hour are unnecessary when they are to be used for detecting ventricular arrhythmia as a predictor of mortality in patients surviving a first acute myocardial infarction.

Prognostic value of myocardial hypoperfusion indexes in patients with suspected or known coronary artery disease

BackgroundWe evaluated the prognostic value of exercise201Tl indexes of myocardial hypoperfusion in patients with suspected or known coronary artery disease.Methods and ResultsPatients were divided into two groups: group I consisted of 332 patients with diagnostic electrocardiographic stress test results and group II consisted of 144 patients with nondiagnostic (inadequate or uninterpretable) stress electrocardiograms. At the 2-year follow-up, 20 hard events (16 cardiac deaths and 4 nonfatal myocardial infarctions) and 80 soft events (coronary revascularization procedures) occurred in group I. Considering total events, thallium imaging provided significant prognostic information in addition to clinical and exercise stress test data in the total study population (p<0.001) and in patients with previous myocardial infarction (p<0.001); in patients without previous infarction, thallium imaging added incremental prognostic value only in those with positive electrocardiographic stress test results (p<0.01). When only hard events were considered, thallium variables added further information only in patients with previous myocardial infarction (p<0.05). In group II at the end of follow-up, 15 hard and 39 soft events had occurred. In these patients occurrence of total (p<0.001), hard (p<0.05), and soft (p<0.001) events was higher in those with abnormal thallium scintigraphic results than in those without. Moreover, no clinical and exercise variable, except history of myocardial infarction, was significantly related to outcome, whereas both indexes of extent and severity of hypoperfusion were significant.ConclusionsThe results of this study demonstrate that scintigraphic indexes of myocardial hypoperfusion obtained by qualitative planar thallium imaging give unique prognostic information in patients with nondiagnostic electrocardiographic stress test results. Thallium imaging provides incremental prognostic information even in patients with diagnostic electrocardiographic stress test results but not in the low-risk subset of patients without previous infarction who have negative electrocardiographic stress test results.