Harold L. Kennedy

Long-term follow-up of asymptomatic healthy subjects with frequent and complex ventricular ectopy.

Abstract From 1973 to 1983 we followed 73 asymptomatic healthy subjects who were discovered to have frequent and complex ventricular ectopy. Ventricular ectopy in these subjects was measured by 24-hour ambulatory electrocardiography, which showed a mean frequency of 566 ventricular ectopic beats per hour (range, 78 to 1994), with multiform ventricular ectopic beats in 63 per cent, ventricular couplets in 60 per cent, and ventricular tachycardia in 26 per cent. Asymptomatic healthy status was confirmed by extensive noninvasive cardiologic examination, although cardiac catheterization of a subsample of subjects disclosed serious coronary artery disease in 19 per cent. Follow-up for 3.0 to 9.5 years (mean, 6.5) was accomplished in 70 subjects (96 per cent) and documented one sudden death and one death from cancer. Calculation of a standardized mortality ratio (Monsons U.S. data, 8th revision) for 448 person-years of follow-up indicated that 7.4 deaths were expected, whereas 2 occurred (standardized mortalit...

Beta-blocker therapy in the cardiac arrhythmia suppression trial

Abstract The Cardiac Arrhythmia Suppression Trial (CAST) showed antiarrhythmic drug suppression of asymptomatic or mildly symptomatic ventricular arrhythmias in survivors of myocardial infarction to be harmful. This study retrospectively searched the CAST results for evidence of mortality and morbidity reduction in patients receiving optional β-blocker therapy. All enrolled (n = 2,611) and suppressed main study (n = 1,735) CAST patients with an ejection fraction of ≤40% were examined using univariate analysis, Kaplan-Meier curves, and a Cox proportional-hazards multivariate analysis with respect to optional β-blocker therapy prescribed at baseline. CAST patients receiving β-blocker therapy had significantly enhanced survival at 30 days, and at 1 and 2 years of follow-up against all-cause and arrhythmic death or nonfatal cardiac arrest. Multivariate analysis showed β-blocker therapy to be independently associated with a one-third reduction in arrhythmic death or cardiac arrest (p = 0.036). In CAST patients with a history of congestive heart failure, β-blocker therapy was independently associated with longer time to occurrence of new or worsened congestive heart failure (p = 0.015). This study supports the secondary preventive benefit of β-blocker therapy in high-risk post-myocardial infarction patients, and calls attention to the possible preventive benefit of β-blocker therapy against proarrhythmic events experienced in the CAST.

Survival of Patients With Nontransmural Myocardial Infarction: A Population-Based Study

A population-based study was conducted in metropolitan Baltimore in which the short- and long-term prognosis of 283 patients with nontransmural myocardial infarction was compared with that of 953 patients with transmural infraction. After simultaneous adjustment for several variables, the in-hospital case fatality rate was greater for patients with transmural (30.1 percent) than with nontransmural (18.3 percent) infarction (P less than 0.01). However, for patients discharged alive from the hospital and followed up for as long as 10 years, no significant differences in survival were found between the groups with transmural and nontransmural infarction. A multiple adjustment procedure yield 3 year case fatality rates of 27.1 percent and 28.3 percent, respectively, for patients with transmural and nontransmural myocardial infarction surviving the acute phase. These results suggest that the long-term prognosis of patients with nontransmural infarction is as guarded as that of patients with transmural infarction and that attempts to prevent subsequent mortality should be diligently pursued in both groups of patients.

Effectiveness of increasing hours of continuous ambulatory electrocardiography in detecting maximal ventricular ectopy: Continuous 48 hour study of patients with coronary heart disease and normal subjects

The effectiveness of 1, 6, 12, 24, 36 and 48 hours of continuous ambulatory electrocardiographic examination in detecting maximal ventricular ectopy was studied in 67 patients with coronary heart disease (45 with myocardial infarction, 22 with angina pectoris) and 23 normal subjects. Two consecutive 24 hour Holter recording examinations provided 48 hours of continuous examination. Ventricular ectopy was detected in 87 percent of patients and 35 percent of normal subjects. Complex forms (multifocal or repetitive patterns) were found in 62 percent and high frequency ectopy (greater than 60/hour) in 30 percent of the patients with coronary heart disease. Examination of either the initial hour of study or an hour of dynamic activity frequently failed to reveal the maximal ventricular ectopy present, particularly with regard to complex types and high frequency. Continuous 6 and 12 hour examinations were less effective than the 24 hour examination, which detected the maximal grade of ventricular ectopy in 71 to 74 percent and the maximal frequency in 58 to 83 percent of patients with coronary heart disease. Detection of maximal complex types and high frequency of ventricular ectopy was one to three times greater with a continuous 24 hour examination than with studies of shorter duration. Patient-recorded diaries showed that 50 to 80 percent of patients were engaged in mild to moderate activity during ventricular ectopy and only 9 percent indicated symptoms during the hours of maximal ventricular ectopy.

Ambulatory blood pressure in healthy normotensive males

Noninvasive ambulatory blood pressure examinations were obtained during 24 hours in 72 healthy normotensive males. Blood pressure and heart rate measurements were analyzed for the mean 24-hour work, home, and sleep periods, for the percent of elevated blood pressure readings, and for the hourly maximum and minimum blood pressure by age per decade. Mean 24-hour ambulatory blood pressure showed no significant differences (p greater than 0.05) for systolic blood pressures among the age groups, but lower diastolic blood pressures were found in males younger than age 40 (p less than 0.05). Few differences existed between mean ambulatory systolic and diastolic blood pressures obtained during the work or home periods, but a significant (p less than 0.01) lowering of mean systolic and diastolic blood pressure occurred during sleep for each age group. There was a trend of an increasing percent of elevated blood pressure measurements with increasing age, although mean blood pressures within each activity period showed few differences. Ninety-two percent of subjects showed their hour of maximum blood pressure during wake activity with broad variability in either the work or home period, whereas 86% of subjects uniformly demonstrated their minimum blood pressure in the early morning hours.

Do Borderline Hypertensive Patients Have Labile Blood Pressure

The 24-hour patterns of ambulatory blood pressure were investigated in borderline (labile) hypertensive patients (office blood pressures fluctuating about 140/90 mm Hg). Sixty-three patients (21 normotensive, 21 borderline hypertensive, and 21 fixed hypertensive) had blood pressures recorded every 7.5 to 15 minutes using noninvasive automatic recorders. The mean 24-hour blood pressures (normotensive, 115 +/- 14/74 +/- 12 mm Hg; borderline hypertensive, 127 +/- 16/81 +/- 13 mm Hg; fixed hypertensive, 143 +/- 17/91 +/- 12 mm Hg) were significantly different from each other (p less than 0.005), but the standard deviations were not significantly different. The percentages of elevated blood pressures on the 24-hour recordings of the borderline hypertensive patients were intermediate between those of the normotensive and fixed hypertensive patients, but within the borderline group there was a broad range in percentage of elevated blood pressures (7.9% to 81.2%). Thus, borderline hypertensive patients have blood pressures no more labile than those in normotensive or fixed hypertensive patients, but because of their broad range of percentage of elevated blood pressures, their pressures are best evaluated with multiple measurements.

Objective evidence of occult myocardial dysfunction in patients with frequent ventricular ectopy without clinically apparent heart disease

Eighteen asymptomatic persons without apparent cardiac disease were incidentally discovered to have frequent ventricular ectopic activity (VEA) (more than a mean of 100 b/hr during 24-hour ambulatory ECG examination) and were found by cardiac catheterization to have normal coronary arteriograms. Thirteen persons (72%) also demonstrated complex (multiform or repetitive patterns) VEA and eight persons were found to have undiagnosed hypertension. Examination of left ventricular (LV) angiographic and hemodynamic data of these persons showed elevated LV end-systolic volume index in 10 persons (56%), elevated LV and end-diastolic volume index in 12 persons (67%) and elevated LV end-diastolic pressure in 11 persons (61%). Although ejection fractions of all but three persons were normal, impaired myocardial contractility, as measured by decreased mean velocity of circumferential fiber shortening (less than 1.0 circ/sec), was found in 10 persons (56%). Abnormalities of LV function were more prevalent in persons with higher mean frequencies of VEA (more than 300 b/hr), but did not seem related to the presence of complex VEA. Etiologic mechanisms of the frequent and complex VEA could not be defined. We conclude that subclinical evidence of myocardial dysfunction is present in some persons without apparent cardiac disease who have frequent VEA as evidence by subtle abnormalities of increased LV volumes and end-diastolic pressure and decreased mean velocity of myocardial circumferential fiber shortening.

Recommended guidelines for training in adult clinical cardiac electrophysiology

Abstract Training in clinical cardiac electrophysiology should take place in an Accreditation Council for Graduate Medical Education accredited cardiology program, and the electrophysiology training program itself should be accredited by the Council. Each trainee must be eligible for board certification in Internal Medicine and either eligible for certification in Cardiovascular Diseases or in a program leading to eligibility. Training faculty should be certified in clinical cardiac electrophysiology or demonstrate equivalent credentials. At least two training faculty members are preferred. The faculty must be dedicated to teaching, active in performing or promoting research and must spend a substantial portion of their time in research, teaching and practice of clinical electrophysiology. A curriculum of training should be established. Faculty experts in the related basic sciences should be available and involved in teaching. The institution should have a fully equipped clinical electrophysiology laboratory and complete noninvasive capabilities. A close working relation with a cardiac surgery faculty member skilled in surgical treatment of arrhythmias is required. Training in application of pharmacologic and all current nonpharmacologic therapies, in the outpatient and inpatient setting, is necessary. The clinical exposure must include all facets of arrhythmia diagnosis and treatment and must be quantitatively sufficient to allow the trainee to develop proficiency. The period of training should not be less than one year in addition to the period of cardiology fellowship required by the ABIM for board eligibility. A continuous period of training is preferred.

Ambulatory electrocardiography. A clinical perspective.

Advances in modern technology have made it possible to record and analyze the electrocardiographic data of ambulatory persons for as many as 24 h or more. This capability and an increasing awareness of cardiac dysrhythmias and myocardial ischemia as a cause of morbidity and mortality have led to the more widespread use of ambulatory electrocardiography in the examination of patients for various clinical conditions. From a clinical viewpoint, we review and summarize the present state-of-the-art of ambulatory electrocardiography and discuss when such studies are indicated, frequently warranted, or may be useful.

Coronary Artery Status of Apparently Healthy Subjects with Frequent and Complex Ventricular Ectopy

Twenty-five subjects from a cohort of 62 asymptomatic, apparently healthy subjects incidentally discovered to have frequent and complex ventricular ectopy were studied with cardiac catheterization and coronary angiography. Fourteen had normal coronary arteries, five noncritical coronary artery disease (less than 50% luminal narrowing), and six significant coronary artery disease (greater than or equal to 50% luminal narrowing). Slightly elevated left ventricular end diastolic pressures were found in all subject subgroups. Characteristics of the ventricular ectopy detected by maximal exercise testing or 24-hour Holter ambulatory electrocardiography did not differentiate those subjects with coronary artery disease from those with normal coronary arteries. This study documents that a minority of apparently healthy subjects with frequent and complex ventricular arrhythmia have significant coronary artery disease and supports a conservative approach to the management of such patients.