Ray A. McKinnis

Prognostic implications of ventricular arrhythmias during 24 hour ambulatory monitoring in patients undergoing cardiac catheterization for coronary artery disease

The prognostic importance of ventricular arrhythmias detected during 24 hour ambulatory monitoring was evaluated in 395 patients with and 260 patients without significant coronary artery disease. Ventricular arrhythmias were found to be strongly related to abnormal left ventricular function. A modification of the Lown grading system (ventricular arrhythmia score) was the most useful scheme for classifying ventricular arrhythmias according to prognostic importance. When only noninvasive characteristics were considered, the score contributed independent prognostic information, and the complexity of ventricular arrhythmias as measured by this score was inversely related to survival. However, when invasive measurements were included, the ventricular arrhythmia score did not contribute independent prognostic information. Furthermore, ejection fraction was more useful than the ventricular arrhythmia score in identifying patients at high risk of sudden death.

Myocardial infarction and stroke

We used a computer data bank to evaluate 740 consecutive patients admitted to a cardiac care unit with myocardial infarction. Stroke occurred in 18 (2.4%) patients in the hospital; the anterior circulation was involved in 76% of strokes. Hospital mortality was 61% in patients with stroke and 13% in patients without stroke. Atrial arrhythmia was a significant (p 5 0.03) risk factor for stroke, but peak creatine kinase and ventricular arrhythmia were not. Cardiac pump failure, apical or anterior-lateral myocardial infarction, and history of previous stroke were associated with an increased risk of stroke. Clinical and pathologic data suggested an embolic etiology for most strokes that complicate acute myocardial infarction.

Prognostic value of ventricular arrhythmias associated with treadmill exercise testing in patients studied with cardiac catheterization for suspected ischemic heart disease

The prognostic information provided by ventricular arrhythmias associated with treadmill exercise testing was evaluated in 1,293 consecutive nonsurgically treated patients undergoing an exercise test within 6 weeks of cardiac catheterization. The 236 patients with simple ventricular arrhythmias (at least one premature ventricular complex, but without paired complexes or ventricular tachycardia) had a higher prevalence of significant coronary artery disease (57 versus 44%), three vessel disease (31 versus 17%) and abnormal left ventricular function (43 versus 24%) than did patients without ventricular arrhythmias. Patients with paired complexes or ventricular tachycardia had an even higher prevalence of significant coronary artery disease (75%), three vessel disease (39%) and abnormal left ventricular function (54%). In the 620 patients with significant coronary artery disease, patients with paired complexes or ventricular tachycardia had a lower 3 year survival rate (75%) than did patients with simple ventricular arrhythmias (83%) and patients with no ventricular arrhythmias (90%). Ventricular arrhythmias were found to add independent prognostic information to the noninvasive evaluation, including history, physical examination, chest roentgenogram, electrocardiogram and other exercise test variables (p = 0.03). Ventricular arrhythmias made no independent contribution once the cardiac catheterization data were known. In patients without significant coronary artery disease, no relation between ventricular arrhythmias and survival was found.

Value of radionuclide angiography for predicting specific cardiac events after acute myocardial infarction

The value of rest and exercise radionuclide angiography (RNA) for predicting specific events including death, recurrent acute myocardial infarction (AMI), coronary care unit readmission for unstable chest pain, and medically refractory angina after AMI was studied in 106 consecutive survivors of AMI. Analysis of the RNA variables using the Cox proportional hazards regression model yielded significant associations of the time to death with ejection fraction at rest and during exercise (X2 = 11.1 and 14.0, respectively). Both variables added significant prognostic information to the clinical assessment (X2 = 4.3 and 5.7, respectively). The change in ejection fraction from rest to exercise predicted the time to coronary artery bypass grafting for medically refractory angina before (X2 = 21.0) and after (X2 = 13.2) adjustment for the clinical descriptors, but did not predict death or other non-fatal events. Significant correlations were found between RNA variables and a variety of clinical descriptors previously reported to have prognostic significance. Clinical and RNA variables that are measures of left ventricular function were predictive of subsequent mortality, whereas those that reflect residual potentially ischemic myocardium were predictive of subsequent nonfatal ischemic events. Rest and exercise RNA after AMI provides significant prognostic information regarding specific events during follow-up independent of that provided by clinical assessment.

Prognostic significance of isolated sinus tachycardia during first three days of acute myocardial infarction

Sinus tachycardia often accompanies other indicators of poor prognosis in acute myocardial infarction. This study was performed to evaluate the prognostic significance of early (Days 1 to 3) in-hospital sinus tachycardia (isolated sinus tachycardia) in the absence of other common indicators of poor prognosis. All patients consecutively admitted directly to the cardiac care unit during a six-year period were evaluated. Patients who had confirmed acute myocardial infarction and no urgent complications during Days 1 to 3 with isolated sinus tachycardia (99 patients) or without isolated sinus tachycardia (159 patients) were included in the study. Both groups were followed for subsequent in-hospital outcome and long-term survival. Univariable and multivariable analysis of historical and demographic characteristics showed no significant differences between the two groups. When clinical descriptors of the infarct were evaluated, the group with isolated sinus tachycardia had a significantly higher mean peak creatine kinase level (p = 0.0007), a larger proportion of anterior infarcts and multiple infarct sites (p less than 0.001) by electrocardiography, a higher incidence of peri-infarction pericarditis (p = 0.007), and a higher incidence of recurrent chest pain (p = 0.03). Twenty-five patients (25 percent) in the group with isolated sinus tachycardia had subsequent urgent complications during the hospitalization compared with 11 patients (7 percent) in the control group (p = 0.00005). In multivariable analysis, isolated sinus tachycardia was an independent predictor of subsequent urgent complications (p = 0.0009) and mortality (p = 0.05).

Out-of-hospital management of cardiac arrest by basic emergency medical technicians

The outcome in 126 consecutive patients with nontraumatic out-of-hospital cardiac arrest was analyzed to determine the effectiveness of a standard ambulance system over 22 months. Therapy was limited to basic life support (that is, administration of oxygen by mask, i.v. fluids, closed-chest massage and artificial respiration) by emergency medical technicians in a community in which less than 1% of the population had been trained in cardiopulmonary resuscitation (CPR). Analyses of patient data were performed to determine the relations between survival to hospital admission or discharge and 6 variables; response time, prior CPR, initial rhythm, acute myocardial infarction, initial blood pressure and initial pulse. Of 126 patients, 28 (22%) survived to hospital admission and 11 (9%) to hospital discharge. Two patient subgroups had a higher discharge rate: those with an initial rhythm of ventricular tachycardia or fibrillation (7 of 50, 14%), and those with an initial blood pressure greater than or equal to 90 mm Hg and a pulse rate of greater than 50 beats/min (3 of 6, 50%). For patients in arrest before ambulance arrival, there was no difference in outcome between those who did or those who did not receive prior CPR. Results of this study can be used as a basis for evaluating and comparing interventions directed toward stabilization of patients during the prehospital phase of cardiac arrest.

Comparative rates of resolution of QRS changes after operative and nonoperative acute myocardial infarcts

An independently developed and previously validated QRS scoring system for estimating myocardial infarct size has been used to compare the development and regression of changes associated with myocardial infarcts occurring in 2 different clinical settings. It is known that QRS changes suggesting myocardial infarction occur after coronary artery bypass grafting. This study compares the magnitudes and time courses of these QRS changes in 40 patients with the QRS changes observed in a control group of 46 patients with nonoperative acute myocardial infarcts. Only patients in both groups who had a baseline electrocardiogram (ECG) with no evidence of previous myocardial infarcts, ventricular hypertrophy, or bundle branch block were included. Both groups attained similar peak QRS scores during the acute phase but different rates of resolution of scores were observed. During the subsequent 2 months, regression of QRS changes occurred more rapidly in the perioperative group than in the control group (43 versus 19%). Rates of regression were similar in both groups during the remainder of the follow-up period, attaining total decreases of 62% in the operative group and 37% in the nonoperative group by 18 months. These results could mean either that factors other than acute infarction are responsible for the perioperative QRS changes or that the infarct healing process in the 2 clinical settings are quite different.

Prognostic effect of bundle branch block related to coronary artery bypass grafting

The incidence and prognostic effect of the development of new perioperative ventricular conduction abnormalities were examined in all patients undergoing coronary artery bypass surgery at Duke University Medical Center between 1976 and 1981. Of the 913 patients included, transient (resolved before discharge) ventricular conduction abnormalities developed in 156 (17%) and persistent (until discharge) changes developed in 126 (14%). Complete right bundle branch block (BBB) was the most frequent type of new ventricular conduction abnormality, followed by left anterior hemiblock and incomplete right BBB (found in 60%, 26%, and 9%, respectively, of all patients with transient changes and 29%, 33% and 26% of all patients with persistent changes). Development of new ventricular conduction abnormalities was most strongly related to date of operation (p less than 0.0001, univariate chi 2 = 122), increasing from 2% transient and 7% persistent in 1976 to 36% transient and 22% persistent in 1981. The incidence was also higher in older patients. Preoperative ejection fraction and number of diseased vessels were related to development of perioperative ventricular conduction abnormalities but were not independently related after adjustment for other baseline characteristics. Contrary to findings in other studies, development of new perioperative ventricular conduction abnormalities, including isolated new left BBB, did not worsen the survival rate in patients followed up to 3 years after surgery.

A comparison of paramedic versus basic emergency medical care of patients at high and low risk during acute myocardial infarction

This prospective study compares the outcome of patients with acute myocardial infarction managed by mobile intensive care (paramedic phase) with that of similar patients managed by basic emergency medical care (control phase) in the same community before the introduction of paramedics. All paramedic-transported patients were managed according to a standard chest pain protocol with use of prophylactic lidocaine and, as needed, treatment for sinus bradycardia, hypotension and life-threatening ventricular arrhythmia. There were no specific interventions for supraventricular tachyarrhythmia or hypertension. All patients were treated under similar in-hospital protocols. Percent mortality in patients with hypotension, the highest risk subgroup in the control phase, was significantly lowered with paramedic-level care (69 versus 10%, p = 0.01). Patients with hypertension, a relatively low risk subgroup during the control phase (16% mortality), were also at lower risk during the paramedic phase (10% mortality). In fact, there was no mortality in either study phase for patients with an initial systolic blood pressure greater than 180 mm Hg. During the combined study phases, patients with normotension and tachycardia demonstrated a tendency toward higher percent mortality (33%) than either patients with normotension without tachycardia (10%) or those with hypertension and tachycardia (6%). Although the overall percent mortality was reduced by 24% (from 21 to 16%), this decrease was largely due to the improvement of patients with hypotension. Investigation into the feasibility of prehospital interventions for the high risk patient with acute myocardial infarction normotension and tachycardia appears warranted.

Psychosocial and physical predictors of anginal pain relief with medical management.

&NA; This study was undertaken to identify psychosocial and physical characteristics that independently predict anginal pain relief. The original study group comprised over 570 patients in whom the characteristics were identified at the time of coronary arteriography and who were followed up after 6 months of standard medical therapy. In the subset of 382 of these patients who were assessed as having NYHA Class III or IV angina at the time of angiography, a multivariable analysis of 101 baseline descriptors showed that higher scores on the MMPI hypochondriasis scale, unemployment, and more severe right coronary occlusion were significant independent predictors of failure to achieve two‐class improvement at follow‐up. These three characteristics also predicted continuing severe angina in a subsequent, independent sample of 91 new patients. These findings could help physicians select appropriate treatment by prospectively identifying patients who are unlikely to respond to standard medical treatment of angina.