Arrhythmia control and other factors related to sudden death in coronary disease patients at intermediate risk

Thirty-three patients with coronary artery disease and frequent, complex ventricular arrhythmias (VA) were followed long-term to evaluate factors related to sudden death (SD). Patients with malignant VA (sustained ventricular tachycardia (VT), resuscitated SD, or acute myocardial infarction) were excluded. Baseline data included angiographic ejection fraction (EF), segmental wall motion, and Holter evidence of frequent (greater than 30/hr) and complex (repetitive) ventricular premature beats (VPBs). Control of VA was attempted with conventional or experimental agents and was defined as greater than or equal to 70% reduction in VPBs, greater than or equal to 90% reduction in couplets, and abolition of nonsustained VT on two consecutive Holter tapes. After 24 +/- 15 months of follow-up on the single most effective agent, 18 patients survived while 15 patients died suddenly. There was no difference between these groups with respect to age, sex, or baseline VA. Survivors had a higher EF (51% vs 34%, p less than 0.001), fewer dyskinetic segments (0.05 vs 1.0, p less than 0.01), and better VA control (83% vs 40%, p less than 0.01) than nonsurvivors. By analysis of variance, VA control was not independent of EF (F = 6.98, p less than 0.01). The 1-, 2-, and 3-year survival rates were 90%, 90%, and 82% for patients with EF greater than or equal to 40% and 22%, 11%, and 11%, for those with EF less than 40% and uncontrolled VA.(ABSTRACT TRUNCATED AT 250 WORDS)     

Differences in heart rate turbulence between patients with coronary artery disease and patients with ventricular arrhythmias but structurally normal hearts

The term "heart rate turbulence" (HRT) indicates the physiologic changes in the sinus cycle that follow a ventricular premature complex; impaired HRT denotes abnormalities in cardiac autonomic function. To investigate whether HRT is impaired in patients with stable coronary artery disease (CAD), we studied 29 patients with documented CAD and frequent (>/=30/hour) ventricular premature complexes on Holter monitoring and 31 patients with frequent ventricular arrhythmias but normal hearts (NH-VA). HRT and heart rate variability analyses were analyzed on 24-hour Holter recordings. HRT variables differed significantly between the 2 groups (turbulence onset -0.20 +/- 1.7% vs -0.67 +/- 2.2%, p = 0.00001; turbulence slope 2.83 +/- 1.9 vs 10.83 +/- 7.4 ms/RR, p = 0.0001 in patients with CAD and NH-VA, respectively). The difference was independent of a history of previous myocardial infarction, left ventricular function, and age. Top quartile turbulence onset values (>-0.26%) and bottom quartile turbulence slope values (<2.12 ms/RR) had similar predictive power in discriminating between patients with CAD and NH-VA (positive predictive value 86.7%, negative predictive value 64.4% for both). Among heart rate variables, bottom quartile SD of all RR intervals values (<96.3 ms) only had the same power of HRT variables in discriminating between patients with CAD and NH-VA. Thus, our data show that HRT variables are impaired in patients with CAD patients versus those with NH-VA, indicating abnormalities in the control of short-term cardiac autonomic mechanisms resulting in decreased vagal activity with likely predominant sympathetic activity.     

Silent myocardial ischemia as a potential link between lack of premonitoring symptoms and increased risk of cardiac arrest during physical stress

The risk of cardiac arrest is increased during strenuous physical exercise in patients with stable coronary artery disease (CAD). Because premonitoring symptoms are rarely observed, silent myocardial ischemia may represent the pathophysiological basis for the induction of malignant ventricular arrhythmias. Holter monitoring was, therefore, performed in 40 consecutive patients entering a randomized intervention trial on progression of CAD. In 20 of 21 participants (95%) in the intervention program greater than or equal to 1 episode of silent myocardial ischemia was observed during the initial training session. The mean duration of silent myocardial ischemia per patient was 25 +/- 13 min/hr of training session. During normal daily activity only 5 patients (24%) experienced greater than or equal to 1 episode of silent myocardial ischemia (p less than 0.001) yielding a mean duration of 0.6 +/- 1.3 minutes of silent myocardial ischemia/hr of ordinary activity per patient (p less than 0.001 vs training session). During a control period of 24 hours without exercise training the incidence (33%) and mean duration of silent myocardial ischemia (0.8 +/- 2.1 min/hr/patient) were similar to those during normal daily activity on the day of the training session. During the training session the occurrence of frequent or repetitive ventricular arrhythmias was related to 10 silent myocardial ischemia episodes detected in 5 patients. During normal daily activity in 1 patient only was the onset of malignant ventricular arrhythmias associated with silent myocardial ischemia (p less than 0.05). Conditions and results of the Holter studies in the control group patients were comparable to those of the patients in the intervention group on the day without physical exercise.(ABSTRACT TRUNCATED AT 250 WORDS)     

Functional and prognostic significance of exercise-induced ventricular arrhythmias in patients with suspected coronary artery disease

Our aims were to assess (1) the relation between exercise-induced ventricular arrhythmia (VA) and myocardial wall motion abnormalities during exercise echocardiography in patients with suspected coronary artery disease (CAD), and (2) the effect of this relation on outcome. We studied the clinical and prognostic significance of exercise-induced VA in 1,460 patients (mean age 64 +/- 10 years; 867 men) with intermediate pretest probability of CAD and no history of previous myocardial infarction or revascularization who underwent exercise echocardiography. Exercise-induced VA occurred in 146 patients (10%). Compared with patients without VA, those with VA had a greater prevalence of abnormal exercise echocardiographic findings (48% vs 29%, p = 0.001) and ischemia on exercise echocardiography (39% vs 22%, p = 0.001), greater increase in wall motion score index with exercise (0.14 +/- 0.28 vs 0.06 +/- 0.18, p <0.0001), and a greater percentage of abnormal segments with exercise (21 +/- 30% vs 9 +/- 19%, p <0.0001). During follow-up (median 2.7 years), cardiac death and nonfatal myocardial infarction occurred in 36 patients. In multivariate analysis of combined clinical and exercise stress test variables, independent predictors of cardiac events were exercise-induced VA (chi-square 4.7, p = 0.03) and exercise heart rate (chi-square 18, p = 0.0001). The percentage of abnormal myocardial segments with exercise echocardiography was the most powerful predictor of VA (chi-square 31, p = 0.0001) and cardiac events (chi-square 15, p = 0.0001). In patients with suspected CAD, exercise-induced VA is associated with a greater risk of cardiac death and nonfatal myocardial infarction. This risk is attributed to the relation between VA and the extent and severity of left ventricular functional abnormalities with exercise.     

N-terminal pro-brain natriuretic peptide predicts myocardial ischemia and is related to postischemic left-ventricular dysfunction in patients with stable coronary artery disease.

BACKGROUND: The N-terminal-pro-B natriuretic peptide (Nt-pro-BNP) is of diagnostic and prognostic value in coronary artery disease (CAD). We assessed the relationship between Nt-pro-BNP and (1) the extent of ischemia on stress myocardial perfusion imaging (MPI), and (2) changes between the basal and postexercise ejection fraction (EF), in stable patients with a normal EF. METHODS AND RESULTS: One hundred and two patients with stable, documented CAD (EF, 62% +/- 8%) underwent an exercise-rest thallium-201 gated-MPI and serial Nt-pro-BNP assays. Myocardial perfusion imaging produced abnormal results in 57 patients (56%; group 1), and normal results in 45 patients (44%; group 2). Median baseline, immediate postexercise, and 3-hour postexercise Nt-pro-BNP values were higher in group 1 than in group 2: 182 vs 85, 201 vs 86, and 212 vs 99 pg/mL, respectively (P < .001 for all). Postexercise EF decreased in group 1 (53% +/- 11% vs 62% +/- 10%, P < .001), but not in group 2 (61% +/- 9% vs 62% +/- 7%, NS). The Nt-pro-BNP ruled out significant ischemia with a negative predictive value of 0.90, whereas patients within the higher tertile of Nt-pro-BNP had a fivefold higher risk of ischemia compared with patients within the lower tertile. CONCLUSIONS: The post-stress increase in Nt-pro-BNP is related to myocardial ischemia and to postischemic left-ventricular dysfunction, and accurately predicts the presence or absence of myocardial perfusion defects.     

Exercise tolerance in patients with and without ventricular aneurysm

To assess the role of a left ventricular aneurysm (VA) in affecting cardiac pump function, 36 patients with an echo-proved postmyocardial infarction (MI) VA underwent maximal symptom limited exercise testing. A control group was formed of 36 patients with a previous MI without VA. The two groups were matched for age, sex, and site of MI. No difference was found in maximal work capacity (MWC), heart rate (HR), systolic blood pressure (BP), delta HR/k rho m, delta BP and VO2max/kg during exercise. MWC in patients with VA and anterior MI was lower as compared to patients with VA and inferior MI (2,839.3 +/- 1,340.9 vs. 4,537.5 +/- 1,453.7, p less than 0.05) while no difference was found between anterior and inferior MI without VA. Patients with VA and anterior MI tolerated lower workloads as compared to those with anterior MI without VA (2,839.3 +/- 1,340.9 vs. 3,996.4 +/- 2,347.1, p less than 0.05). No difference was found between patients with inferior MI with or without VA. No major adverse cardiovascular events occurred during or after the tests. Patients were grouped for echo-estimated ejection fraction (EF) less than 30%, 30-50% and greater than 50%. Only 1 patient without VA was found among patients with EF less than 30%. In both groups MWC increased with the increase of EF. Patients with VA, anterior MI and EF less than 30% showed the lowest exercise tolerance (2,216.6 +/- 529.1), and no patient with VA and inferior MI exhibited EF less than 30%. In conclusion, in patients with VA, exercise testing is a safe and useful tool to evaluate the functional capacity of the residual 'non-aneurysmatic' myocardium.     

Functional recovery after coronary artery bypass grafting in patients with severe left ventricular dysfunction and preserved myocardial viability in the left anterior descending arterial territory as assessed by thallium-201 myocardial perfusion imaging.

To evaluate the functional recovery after coronary bypass surgery in patients with severe left ventricular (LV) dysfunction (ejection fraction (EF) < or = 35%), 100 consecutive patients with viable myocardium in the territory supplied by the left anterior descending artery (LAD) underwent coronary bypass grafting. In addition, cardiac catheterization and single-photon emission computed tomography (SPECT) perfusion imaging with thallium-201 were repeated 1-year postoperatively. Although 12 patients with severe LV dysfunction were preoperatively in a worse New York Heart Association functional class (3.1+/-0.7 vs 2.4+/-0.8; p<0.01), had a higher incidence of heart failure (10/12 vs 14/88; p<0.001) and had a worse LVEF (29+/-5 vs 61+/-14%; p<0.001) compared with 88 patients without severe LV dysfunction, the operative mortality was similar in the 2 groups (1/12 vs 2/88; p=NS). The postoperative NYHA functional class in the patients with severe LV dysfunction was similar to that in the patients without such dysfunction (1.6+/-0.7 vs 1.3+/-0.6; p=NS). In addition, the 1-year postoperative study revealed a significant improvement in the thallium defect score in both the LAD territory (1.7+/-1.2 to 0.7+/-1.0, p=0.01) and all the territories (5.2+/-2.2 to 3.2+/-1.9, p=0.002) in patients with severe LV dysfunction, whereas no improvement in defect score was found in either of these territories in those without severe LV dysfunction (LAD: 0.6+/-1.4 to 0.4+/-1.2, p=NS; All: 1.9+/-2.2 to 1.8+/-2.0, p=NS). Furthermore, a marked 1-year postoperative improvement (15-24%; 95% confidence interval) in LVEF (29+/-5 to 48+/-10%, p<0.001) was demonstrated in patients with severe LV dysfunction, but not in those without such dysfunction (60+/-13 to 61+/-11%, p=NS). These results indicate that myocardial viability in the LAD territory, as demonstrated by thallium-201 SPECT perfusion imaging, predicts a significant improvement in functional class and LVEF of at least 10% or more after coronary artery bypass grafting in patients with severe LV dysfunction.     

Heart rate variability in heart failure

BACKGROUND: Heart rate variability (HRV) depicts the functional status of the autonomic nervous system and its effects on sinus node. Recently, HRV analysis has been introduced in patients with heart failure (CHF) to identify those who are at risk of cardiac death. AIM: To analyse HRV in patients with CHF with depressed left ventricular ejection fraction (EF) and to relate HRV parameters to EF, NYHA functional class and other clinical parameters. METHODS: The study group consisted of 105 patients with CHF (88 males, 17 females, mean age 54+/-12 years); 77 patients had ischaemic cardiomyopathy, and 28 - dilated cardiomyopathy. All patients were in NYHA class II-IV and had EF <40%. The mean value of echocardiographically assessed EF was 26.9+/-8.3%. The control group consisted of 30 gender- and age-matched healthy subjects. HRV analysis was performed in the time-domain from 24-hour Holter ECG. RESULTS: All HRV variables were significantly lower in patients with CHF than in controls. Patients with NYHA class II had higher values of SDNN and SDANN than those in class III or IV. Patients with sustained or non-sustained ventricular tachycardia (VT) detected during Holter monitoring had lower SDNN and SDANN values than those without VT. Patients with diabetes had significantly lower SDNN and rMSSD values than the patients without diabetes. Similar results were found when patients with or without hypertension were compared. HRV parameters were similar in patients either with ischaemic or dilated cardiomyopathy. Also the values of EF were similar (27.4+/-8.4 vs 25.0+/-8.3%, respectively, NS). In the whole group of patients with CHF the values of SDNN and SDANN significantly correlated with EF (SDNN p<0.001, r=0.42; SDANN p<0.001, r=0.51). This correlation was stronger in the subset of patients with ischaemic cardiomyopathy (SDNN p=0.002. r=0.54; SDANN p=0.002; r=0.53) than in those with dilated cardiomyopathy (SDNN p=0.012, r=0.23; SDANN p=0.008, r=0.42). A significant negative correlation was found between all HRV parameters and NYHA class (SDNN p<0.001, r = -0.33; SDANN p<0.001, r = -0.38; rMSSD p<0.001, r = -0.13). CONCLUSIONS: HRV is depressed in patients with CHF compared with healthy subjects. Among patients with CHF, HRV is further decreased in patients with more advanced NYHA class, lower EF and in those with diabetes, hypertension or VT on Holter monitoring.     

Left ventricular pressure/volume relationship in aortic regurgitation

In this study we examined the left ventricular pressure/volume relationship in 39 patients with moderate or severe aortic regurgitation (AR) and 15 normal subjects. The patients with AR were divided into two groups; patients with normal resting ejection fraction (EF greater than or equal to 50%, group I, n = 21) and patients with abnormal EF (group II, n = 18). The patients in group I were younger (p less than 0.005), exercised to a higher workload, and had better exercise tolerance than patients in group II (p less than 0.01). The patients' exercise heart rate and blood pressure were not significantly different between the two groups. During exercise tests nine patients in group I and seven patients in group II had normal EF response (greater than or equal to 5% increase) (p = NS). The peak systolic blood pressure to end-systolic volume index ratio (SBP/ESVI) was higher in normal subjects than in patients in groups I and II, at rest it was (4.3 +/- 1.0 vs 2.6 +/- 1.2 vs 1.6 +/- 0.8, respectively, p less than 0.0001) and during exercise it was (7.6 +/- 1.8 vs 4.2 +/- 1.4 vs 2.6 +/- 1.3, respectively, p less than 0.0001). The resting SBP/ESVI ratio was below the lower normal limit in 12 patients (57%) in group I and in 16 patients (89%) in group II. Also, the exercise SBP/ESVI ratio was below the lower normal limit in 17 patients (81%) in group I and all of the patients (100%) in group II. Multivariate discriminant analysis identified the change in SBP/ESVI (F = 34.8) and resting end-diastolic volume (F = 6.7) as independent predictors of the EF response to exercise. Thus, most patients with AR, including those with normal resting EF or normal EF response to exercise, have abnormal SBP/ESVI at rest or during exercise.     

Relation among exercise-induced ventricular arrhythmias, myocardial ischemia, and viability late after acute myocardial infarction

This study assesses the relation between exercise-induced ventricular arrhythmia (VA) and scintigraphic markers of myocardial ischemia and viability in patients referred for exercise stress testing late after acute myocardial infarction. We studied 171 patients (144 men, age 57 +/- 10 years) with resting wall motion abnormalities by exercise stress testing in conjunction with methoxyisobutyl isonitrile (MIBI) single-photon emission computed tomography at a mean of 4.1 years after myocardial infarction. Ischemia was defined as reversible perfusion abnormalities. Myocardial viability was considered in myocardial segments with resting wall motion abnormalities in the presence of normal perfusion, a reversible defect or a fixed defect with regional MIBI uptake > or = 50% of maximal uptake. Exercise-induced VA occurred in 46 patients (27%). Patients with VA had a higher prevalence of infarct-related artery stenosis (43 [93%] vs 93 [74%], p < 0.01), peri-infarction ischemia (32 [70%] vs 54 [43%], p < 0.005), and ischemia in > or = 2 vascular regions (20 [43%] vs 27 [22%], p < 0.01) than patients without VA. Reversible defects were detected in 39 of 97 dyssynergic segments (40%) in patients with versus 40 of 248 dyssynergic segments (16%) in patients without VA (p < 0.0001). In dyssynergic segments without reversible perfusion abnormalities, the percent resting MIBI uptake was > or = 50% in 39 of 58 segments (67%) in patients with versus 63% in 131 of 208 segments in patients without VA (p = NS). The percentage of viable segments was 80% and 69% in patients with and without VA, respectively (p < 0.05). It is concluded that patients with exercise-induced VA late after myocardial infarction have a higher prevalence of ischemia in the peri-infarction zone and in multivessel distribution. Myocardial ischemia in the dyssynergic myocardium appears to be a major mechanism underlying the occurrence of VA in these patients.     

Predictors of left atrial spontaneous echocardiographic contrast or thrombus formation in stroke patients with sinus rhythm and reduced left ventricular function

The objective of the present study was to identify predictors of left atrial spontaneous echocardiographic contrast (SEC) or thrombus in patients with stroke with sinus rhythm and left ventricular dysfunction. Of 500 consecutive patients with stroke, 48 with sinus rhythm and reduced left ventricular ejection fractions (EFs) < or =45% were examined. Ten patients presented with SEC or thrombus. The patients with SEC or thrombus had larger left atrial diameters (47 +/- 4 vs 42 +/- 6 mm, p <0.05), smaller EFs (30 +/- 9% vs 38 +/- 8%, p <0.01), and slower left atrial appendage (LAA) flow velocities (42 +/- 13 vs 61 +/- 17 cm/s, p <0.01). Multivariate analysis identified EF < or =35% and LAA flow velocity < or =55 cm/s as predictors of SEC or thrombus (p <0.05). Patients with stroke with sinus rhythm and moderate- to high-grade reduction of the left ventricular EF represent a risk group for a left atrial source of embolism and should undergo transesophageal echocardiography.     

Analysis of left ventricular systolic function using midwall mechanics in patients >60 years of age with hypertensive heart disease and heart failure

Normal ejection fraction (EFs) is often equated with normal systolic function. However, midwall mechanics reveal systolic dysfunction in hypertensive heart disease accompanied by hypertrophic remodeling. Midwall mechanics are unstudied in patients with acute diastolic heart failure (HF). This study analyzed left ventricular (LV) midwall stress-shortening relations in 61 patients aged >60 years with hypertensive heart disease, HF, and normal EF. Sixty-one hypertensive patients (mean age 78 +/- 10 years) who presented with HF, each with an EF >50%, underwent echocardiography. Midwall mechanics were compared with those of 79 controls (mean age 75 +/- 8 years) without structural heart disease. Relative wall thickness (0.63 +/- 0.11 vs 0.46 +/- 0.10 mm) and LV mass (237 +/- 67 vs 177 +/- 57 g) were significantly greater in patients with HF compared with controls. Mean EFs were similar in patients with HF and controls (64 +/- 9% vs 67 +/- 9%). Although mean endocardial fractional shortening (35 +/- 7% vs 37 +/- 7%) was not significantly different, midwall shortening in patients with HF was significantly less compared with controls (16 +/- 2% vs 19 +/- 3%, p <0.05). Eighteen of the 61 patients with HF (30%) had midwall shortening that was <95% confidence intervals of the normal midwall stress-shortening relations. By this criterion, these patients had systolic dysfunction despite normal EF; they had smaller LV chambers (in dimension and volume), greater relative wall thickness, and smaller stroke volumes. In conclusion, almost 1/3 of patients hospitalized with diastolic HF had systolic dysfunction, characterized by abnormal midwall stress-shortening relations.     

Predischarge low-dose dobutamine test and prediction of left ventricular function at 1 year in patients with a first anterior myocardial infarction

BACKGROUND: It is unclear whether spontaneous improvement in contractility following acute myocardial infarction (AMI) is related to severity of predischarge systolic dysfunction and can be predicted by isotopic ventriculography with a low-dose dobutamine test (DBT). HYPOTHESIS: Spontaneous improvement in contractility would be similar in patients with more preserved and those with depressed ventricular function, and a DBT test could predict it. METHODS: Left ventricular ejection fraction (LVEF), regional contractility score (RCS), and left ventricular end-diastolic volume index (EDVI) at predischarge, during DBT, and at 1 year were analyzed in 43 patients with a first anterior ST-elevation AMI. RESULTS: Changes produced by DBT in patients with LVEF < 40%, RCS > or = 3, or EDVI > or = 70 ml/m2 were smaller than in those observed at 1 year (LVEF: 30 +/- 5-35 +/- 7%, p < 0.001, vs. 39 +/- 10%, p = 0.005; RCS: 4.9 +/- 1.4-4.6 +/- 2.0, NS, vs. 3.4 +/- 2.0, p < 0.02; EDVI: 92 +/- 14-86 +/- 22, NS, vs. 78 +/- 23 ml/m2, p < 0.03). In contrast, in patients with EF > or = 40%, RCS < 3 or EDVI < 70 ml/m2, changes with DBT tended to be greater than those observed at 1 year (LVEF: 52 +/- 8-57 +/- 11%, p < 0.004 vs. 55 +/- 11%, p < 0.04); RCS: 1.1 +/- 0.9-0.8 +/- 0.8, NS, vs. 1.1 +/- 1.1, NS; and EDVI: 51 +/- 9-47 +/- 11, p < 0.005, vs. 54 +/- 13 ml/m2, NS). CONCLUSIONS: Among patients with a first anterior AMI, spontaneous improvement in contractility at 1 year was greatest in those with a more depressed ventricular function or a dilated ventricle, but its magnitude was underestimated by a predischarge DBT test.     

A noninvasive comparison of left ventricular performance in sickle cell anemia and chronic aortic regurgitation

Abnormalities of the cardiovascular system are common in patients with sickle cell anemia (SS). Noninvasive testing to document left ventricular dysfunction has yielded conflicting results. Left ventricular performance was evaluated in 27 patients with SS by M-mode and 2-D echocardiography, and systolic time intervals. Comparisons were made to 25 normal controls, and to 22 patients with chronic aortic regurgitation. Left ventricular diastolic diameter (LVDD) and cardiac index (CI) were significantly greater in the patients with SS than in controls (LVDD 5.3 +/- 0.4 vs. 4.7 +/- 0.5 cm; CI 4.2 +/- 1.3 vs. 3.1 +/- 0.8 liters/min/m2; both p less than 0.001). Left ventricular ejection fraction (EF) was slightly, but significantly less (62.9 +/- 7.3 vs. 67.0 +/- 5.4; p less than 0.05). In comparison to the patients with chronic aortic regurgitation, the LVDD in the patients with SS was slightly, but significantly lower (LVDD 5.3 +/- 0.4 vs. 5.9 +/- 0.6 cm; p less than 0.05). There was no significant difference between the patients in EF or CI (EF 62.9 +/- 7.3 vs. 63.3 +/- 4.4; CI 4.2 +/- 1.3 vs. 5.0 +/- 1.0 liters/min/m2; NS). Left ventricular EF was below 55 in three patients who also had hypertension at the time of examination. We conclude that patients with SS have resting left ventricular performance consistent with a high output state. Significant left ventricular dysfunction related to sickle cell disease alone was not demonstrated in this population, although the addition of hypertension appears to deleteriously affect resting left ventricular performance.     

老年冠心病患者PCI后症状及动态心电图分析

目的探讨老年冠心病患者经皮腔内冠状动脉成形术（PTCA）及支架置入术后心肌缺血与临床症状及心律失常的关系。方法对103例老年冠心病患者成功行PTCA及支架置人手术前后的临床症状及动态心电图结果进行统计分析。结果103例老年冠心病患者术后动态心电图显示24h心肌缺血发作次数、ST段压低幅度、ST段压低总时间、缺血发作平均时间和严重心律失常发生率和心脏事件发生率明显低于手术前（分别为4．1±1．1次vs9．1±1．6次，1．4±0．5mm vs 3．0±0．6mm，28．3±5．6min vs 207．1±13．3min．4．8±0．9min vs 19．2±2．2min和25．2％．vs 66．0％，P分别〈0．001、〈0．001、〈0．001、〈0．001和〈0．001）；动态心电图记录到的心肌缺血发作时，临床发生典型心绞痛症状的比例明显低于手术前（为7．8％vs43．7％，P〈0．001），传导阻滞发生率无显著变化（p〉0．05）。结论成功的PTCA及支架置入手术能明显改善冠心病患者心肌缺血发作次数、缺血程度、缺血持续的时间以及严重心律失常的发作次数，缓解心绞痛症状，提高生活质量；但对老年患者已存在的传导阻滞改善不明显。动态心电图可作为一种对PTCA及支架置入术疗效及患者预后有价值、无创性的评价方法。     

Effects of injection site on the accuracy of thermal washout right ventricular ejection fraction measurements in clinical and model investigations

The purpose of this investigation was to improve the accuracy of measurement of thermal right ventricular ejection fraction (RVEF) using the modified Swan-Ganz catheter. Three serial ejection fractions (EFs) (EF1, 2, 3) and the mean were calculated, based on Holt's theory. RVEFs were compared between right ventricular (RV) and atrial (RA) injection in ten intensive care unit (ICU) patients using a modified catheter having RV and RA orifices (15 cm and 30 cm from the distal end, respectively), and paired duplicate (two patients) or triplicate (eight patients) measurements were performed. To determine what factors interfere with RVEF, a model heart (with diastolic volume of 150 ml) was constructed, in which model injection of cold water to the direct inflow tract (RA), to the direct mixing chamber (RV), or through the catheter running in the inflow tract were compared. When EFs were compared between RV and RA injection, those for the former were greater (RV vs RA in EF1 and EFmean: 0.46 +/- 0.15 vs 0.23 +/- 0.11 in EF1, and 0.45 +/- 0.13 vs 0.28 +/- 0.11 in EFmean, mean +/- SD, p less than 0.01). When the serial EFs were compared in each injection type, in the RV injection EF3 was the smallest as was EF1 in the RA injection. The same phenomenon was observed in the model as in the patients, and moreover when cold water was injected in RA through a catheter running through the circuit, EFs were greatly underestimated (EF1 = 0.29 +/- 0.02 at preset EF = 0.4). We conclude that these phenomena were caused by sluggish movement of the cold indicator from RA to RV when injected into RA, and by interference with the cooled cardiac chamber and catheter. Consequently, the first or second EFs obtained from RV injection might be closest to the actual values because of the least interference with those factors.     

Prevalence of circadian variations and spontaneous variability of cardiac disorders and ECG changes suggestive of myocardial ischemia in systemic arterial hypertension.

BACKGROUND. Systemic hypertension is a well-known risk factor for coronary artery disease and sudden cardiac death. Recent interest focused on the presence of malignant ventricular arrhythmias (VA) and myocardial ischemia in hypertensive patients and provided a potential link for fatal tachyarrhythmic events. METHODS AND RESULTS. We studied 150 untreated normokalemic hypertensive patients (56 +/- 9 years; 56 women and 94 men) without manifest coronary artery disease to determine prevalence, severity, and interaction of VA and significant ST segment changes induced by daily activities. One third of the patients were randomized to 4 weeks of placebo and restudied for spontaneous variability of the two parameters. All patients were included in a 3-year follow-up study. VA were observed in 129 of 150 hypertensive patients (86%) and peaked in the early morning and late afternoon. Twenty-two patients (15%) had ventricular pairs, and 20 patients (13%) had nonsustained ventricular tachycardia. Transient ST segment depression observed in 47 patients (33%; mean incidence, 2.7 +/- 0.8 episodes/24 hr) showed a characteristic circadian variation similar to VA and were asymptomatic in 93% of the episodes. At the time of transient ST segment depression, VA increased 4.6 times (p less than 0.01). After 4 weeks of placebo, marked variations in the incidence of VA (VA suppression rate -100%, or increase greater than 400%) were observed in 29% of the patients, and in 60% of all patients repetitive VA were present in only one of the two Holter recordings. Day-and-night variations of VA and transient ST segment changes were highly reproducible during the placebo period. After 3 years of follow-up, eight of 146 patients (5%) had suffered myocardial infarction, and five patients had died from cardiac events (three patients died from sudden cardiac death). Logistic regression analysis revealed left ventricular hypertrophy (relative risk, 6.1; p less than 0.01) and transient ST segment abnormalities during daily activities (relative risk, 4.4; p less than 0.05) to be of independent prognostic significance to predict cardiac events during follow-up instead of repetitive VA (relative risk, 1.3; NS). CONCLUSIONS. VA associated with a high spontaneous variability and predominantly asymptomatic transient ST segment changes are common in hypertensives; the interaction of both risk factors may provide an important link for fatal VA. Antiarrhythmic therapy is not to be recommended in the majority of patients. Presence of left ventricular hypertrophy and transient ST segment changes were the most powerful predictors of cardiac events during the follow-up.     

Effects of age on responses to isometric exercise. Isometric handgrip in noninvasive screening for cardiovascular disease.

Isometric handgrip (IHG) imposes an acutely increased afterload on the left ventricle. Utilizing systolic time intervals, we studied various responses to IHG, measured as changes from resting values with near-maximum IHG, in old normal (ON) subjects, young normal (YN) subjects, and old patients with hypertensive heart disease (HHD) and patients with coronary artery disease (CAD). There were no differences in responses to IHG between ON and patients with HHD or patients with CAD. However, there were clear differences between the responses of ON and YN subjects. Increase in heart rate (HR) was much more prominent in YN (ON vs. YN = +11.6 +/- 2.6 vs. +15.6 +/- 5.7 beats per minute p less than 0.001). Pre-ejection period (PEP) end isovolumic contraction time (IVCT) increased in ON but decreased in YN (PEP + 6.2 +/- 1.7 vs. -11.0 +/- 3.7 msec., p less than 0.001; IVCT +8.1 +/- 2.2 vs. -13.8 +/- 3.4 msec., p less than 0.001. Shortening of LVET was much more marked in YN (-6.5 +/- 4.1 VS. -63.3 +/- 9.9 msec. p less than 0.001), but this was entirely due to the HR differences since there was no difference in ejection time index (+ 5.1 +/- 3.4 vs. -0.4 +/- 7.3 msec. p greater than 0.5). IHG produced no significant differences between ON and YN in the timing of the "mitral" component of the first heart sound (q-Im), in the ratio PEP/LVET, or in pulse transmission time (PTT). By contrast, resting control PTT was markedly short in ON, especially those with CAD. Resting PTT in ON was 27.1 +/- 2.6 msec.; in YN 43.7 +/- 1.4 msec.; in CAD patients 20.7 +/- 1.3 msec. We conclude that even near-maximal IHG does not seem to be an adequate noninvasive screening test for cardiovascular disease in that age alone seems to have the most significant influence on the responses.     

Age-related changes in left ventricular diastolic performance

Previous studies show that the radionuclide-derived indices of left ventricular (LV) diastolic performance are abnormal at rest in many patients with coronary artery disease (CAD), even in those with normal resting ejection fraction (EF) and no prior myocardial infarction. This study examined the age-related changes in LV peak filling rate and time to peak filling rate in 65 subjects between the ages of 20 and 75 years with a low likelihood of CAD. All subjects had normal resting EF (greater than or equal to 50%), and none had prior infarction. There was a significant age-related decline in resting peak filling rate (r = -0.47, p less than 0.001) and exercise peak filling rate (r = -0.52, p less than 0.001), but no age-related effect in the time to peak filling rate. Of the 29 subjects less than 50 years of age, 26 (90%) had resting peak filling rate greater than or equal to 2.5 EDV/sec (3.1 +/- 0.6, mean +/- SD) compared to 17 of 36 subjects (47%) greater than or equal to 50 years of age (2.6 +/- 0.6) (p = 0.002). In a subgroup of 28 subjects with a history of hypertension, the age-related effect was more marked than in the remaining 37 subjects without such a history (r = -0.66 vs -0.33). Thus, the peak filling rate at rest and during exercise decreases with advancing age; the high frequency of observed abnormality in the peak filling rate at rest in patients with CAD may conceivably be related in part to age differences between patients with CAD and the control group.     

Differences in left ventricular ejection fraction and volumes measured at rest and poststress by gated sestamibi SPECT.

BACKGROUND: Some studies suggested that the poststress left ventricle ejection fraction (LV EF) is lower than rest LV EF in patients with stress-induced ischemia. METHODS AND RESULTS: By using a 2-day protocol and 30 mCi Tc-99m sestamibi, LV EF, end-systolic volume (ESV), and end-diastolic volume (EDV) were measured with gated SPECT. Of 99 eligible patients, 91 had technically adequate studies. Poststress LV EF minus rest LV EF was defined as DeltaLV EF. DeltaEDV and DeltaESV were similarly defined. Rest and poststress LV EF (r = 0.89), EDV (r = 0.78), and ESV (r = 0.93) were highly correlated (P <.001). Rest LV EF, EDV, and ESV were not significantly different between patients with and without stress-induced ischemia. DeltaLV EF was significantly lower in patients with stress-induced ischemia (-3.5% +/- 4.5% vs -1.1% +/- 4.7%, P = .02). Mean LV EF poststress in ischemic patients was 55.0% +/- 10.5% vs 61.2% +/- 10.0% in nonischemic patients (P = .008). However, only 1 patient (3%) with ischemia had DeltaLV EF that exceeded the 95% confidence limit of DeltaLV EF for normal patients. Ischemia was significantly associated with increased DeltaEDV and DeltaESV (P < .01). CONCLUSIONS: Stress-induced ischemia is associated with poststress reduction in LV EF and increased poststress EDV and ESV. However, the effect of ischemia on the difference between poststress and rest EF measurements is modest and rarely exceeds the confidence limits in normal patients undergoing 2-day protocols. In most patients, poststress LV EF is an accurate reflection of rest LV EF.