Arthur J. Moss

Ventricular ectopic beats and their relation to sudden and nonsudden cardiac death after myocardial infarction.

The role of ventricular ectopic beats (VEBs) in identifying patients who die of cardiac cause in the posthospital phase of myocardial infarction was evaluated in 940 patients who survived an acute coronary event. Six-hour Holter ECG recordings were obtained before hospital discharge, and VEBs were classified as complex (bigeminal, multiform, repetitive or R on T), simple (one or more VEBs that did not have complex patterns), or not present. Patients were followed 1-60 months (average 36 months) and cardiac mortality was categorized as sudden (⩾ I hour) or nonsudden (> I hour) among 98 witnessed cardiac deaths. Complex VEBs were associated with a significantly increased cardiac death rate, but did not discriminate between sudden and nonsudden death. Simple VEBs were associated with a 3-year cardiac mortality rate intermediate between those with complex and those with no VEBs. The relationship between complex VEBs and cardiac mortality was independent of 10 relevant clinical variables.

Digitalis-associated cardiac mortality after myocardial infarction.

The effect of digitalis therapy on 4-month posthospital cardiac mortality was investigated in 812 patients who survived the hospital phase of acute myocardial infraction. A stepwise multiple logistic reg.ression analysis. was used to identify variables associated with increased mortality and to adjust for differences in. confounding variables between digitalis and nondigitalis patients. The major 4-month mortality (10 of 26 patients [38.5%]) occurred in digitalis-treated patients with congestive heart failure in the coronary care unit and complex ventricular. premature. depolarizations (VPDs) on a predischarge Holter recording. Logistic analyses that controlled for confounding variables indicated that digitalis use contributed to the increased mortality rate in this high-risk subset. The predicted mortality difference due to digitalis in patients with congestive heart failure and.complex VPDs, adjusted for relevant nondigitalis risk factor variables, was 30% (90% confidence interval 18-42%). This retrospective study suggests that digitalis use increases the early posthospital mortality of myocardial infarction patients with combined electrical and mechanical dysfunction.

Survivorship patterns in the posthospital phase of myocardial infarction.

A prospective postinfarction follow-up study was used to identify subsets of patients with different survival patterns. Nine hundred forty patients who survived the hospital phase of an acute myocardial infarction were followed for 12-60 months. During the 5-year follow-up, 115 patients died of cardiac causes. Univariate analysis showed that prior myocardial infarction (PMI), left ventricular dysfunction (LVD) in the CCU, one or more ventricular premature depolarizations (VPDs) on a 6-hour Holter recording, and anterior myocardial infarction were significantly (p < 0.01) more frequent in patients who died of cardiac causes than in survivors. Survivorship analyses revealed a variety of survival patterns, depending on the presence or absence of the risk factors PMI, LVD, VPD and anterior infarction, as well as their interactive combinations. A combination of anterior infarction with LVD and VPDs identified a high-risk subset that made up 15% of the myocardial infarction population, and this group had 6-month and 3-year survival rates of 85% and 70%, respectively. After we excluded the high-risk subset, PMI, LVD and VPD each had significant yet independent influence on survival, with PMI having a greater effect on mortality than either LVD or VPDs. A low-risk subset that made up 24% of the population was identified by the absence of PMI, LVD and VPDs, and this group had a 3-year survival of 94%.

The Posthospital Phase of Myocardial Infarction Identification of Patients with Increased Mortality Risk

A prospective follow-up study was carried out on 100 patients recovering from acute myocardial infarction in order to develop a method for identifying those patients who are at high risk of late cardiac death. Variables, which were recorded just prior to the patients hospital discharge after the acute attack, included six rhythm parameters from a six-hour tape ECG recording, three indices of severity of the acute coronary event, and seven nonspecific variables. Seventy-nine of the 100 patients survived a two-year follow-up, and 17 of 21 patients who died succumbed from cardiac-related problems. A stepwise discriminant analysis program was used to derive a formula which would predict the likelihood of surviving two years after a myocardial infarction. The population was divided into two groups on the basis of the presence (Group A, N = 67) or absence (Group B, N = 29) of ventricular premature beats on the initial ECG tape recording. In Group A, 91% of both the survivors and nonsurvivors were correctly identified by a discriminant combination of three arrhythmia parameters and age. In Group B, 75% of the survivors and 100% of the nonsurvivors were properly classified simply from age and one index of severity.

Brady-Tachy syndrome.

BRUPT CHANGES in the heart rate may be associated with a variety of symptoms. In the mid-eighteenth century, Morgagni,’ Adams,* and Stokes3 described a group of patients with intermittent slow or absent heart action and concomitant loss of consciousness, often culminating in death. Subsequent studies of this condition have identified a primary disturbance in atrioventricular conduction as a cause of the bradycardia, and the mechanism of syncope (Adams-Stokes syncope) may be either asystole or ventricular tachyarrhythmias complicating the heart block. Recently, a diverse group of patients with somewhat similar syncopal episodes but without atrioventricular block has been described in the medical literature. Disorders of sinus node function with atrial bradycardia and failure of subsidiary pacemakers to escape at a physiologic rate are the electrophysiologic abnormalities common to this group of patients. Descriptive terms such as sick sinus node,4-6 lazy sinus node, ’ inadequate sinus mechanism,8 sluggish sinus node,’ and sinoatrial syncope lo have been applied to the impaired sinus mechanism. An interesting and therapeutically challenging subgroup includes those patients with paroxysmal tachycardia complicating the atria1 bradycardia.“,” During the past 20 yr, more than 60 cases of

The early posthospital phase of myocardial infarction. Prognostic stratification.

Prognostic stratification was carried out on 518 patients ≤ 65 years of age who were discharged from the hospital following a definite or probable acute myocardial infarction and followed for four months. The total population was made up of 272 patients hospitalzed in 1973 and 246 patients hospitalized in 1974; one hundred and forty-two variables were collected on each patient. The clinical characteristics of the 1973 and 1974 populations were remarkably similar, and both groups had a four-month posthospital cardiac mortality rate of 4%. Two prognostic stratification schemes were developed on the 1973 population which identified low and high risk groups with meaningfully different four-month cardiac death rates. Both stratification schemes were tested on the 1974 population, and one of the two schemes was validated as identifying a significantly increased cardiac mortality rate in the high as opposed to the low risk group. The four-month posthospital cardiac mortality rate was 3% in the low and 14% in the high risk group (Z = 2.70, P < 0.003). The high risk group was characterized by two or more of the following characteristics: 1) history of angina at ordinary levels of activity or at rest; 2) CCU hypotension and/or congestive heart failure; 3) ventricular premature beat frequency ≥ 20/hr on a sixhour electrocardiographic tape recording. The low risk group had none or only one of the above characteristics. The prognostic power of this stratification scheme is such that sixteen percent of the posthospital population can be identified as high risk, and this subgroup contains forty-six percent of the patients who die of cardiac cause in the four-month posthospital interval.

Termination and inhibition of recurrent tachycardias by implanted pervenous pacemakers.

Three patients are described with recurrent paroxysmal tachycardia who required implanted pervenous demand pacemakers for the control of repetitive tachyarrhythmias. One patient had frequent weekly episodes of life-inhibiting supraventricular tachycardia (SVT) lasting hours to days and refractory to antiarrhythmic drugs. A coronary sinus atrial demand pacemaker at 72 beats per minute was implanted. During the subsequent two months, the patient quickly terminated nine episodes of SVT by activating the generator with an external magnet and competitively pacing the atrium. The second patient had frequent daily episodes of SVT and secondary angina despite vigorous antiarrhythmic medication. Demand ventricular pacing at a rate of 88 beats per minute prevented the recurrence of SVT during the seven month follow-up. A third patient with an old myocardial infarction had frequent biweekly episodes of ventricular tachycardia (VT) refractory to conventional treatment. A ventricular demand pacemaker was implanted, and three episodes of VT were terminated by magnetically activated competitive ventricular pacing at 64 beats per minute. Augmentation of the demand pacemaker rate to 86 beats per minute inhibited the recurrence of VT during a five month follow-up. The rates of the tachycardias were less than 160 beats per minute in all three cases, and evidence suggests a re-entrant or reciprocating mechanism for the tachyarrhythmias. The electrophysiologic rationale for pacemaker therapy in certain types of recurrent SVT and VT is discussed.

Permanent pervenous atrial pacing from the coronary vein.

Permanent pervenous atrial pacing from the coronary vein has been attempted in 14 patients. Several types of arrhythmias including symptomatic bradycardia, “bradytachy” syndrome, and refractory ventricular tachyarrhythmia-fibrillation have been successfully treated with pervenous atrial pacing in 10 patients for 1 to 30 mo. Longterm atrial pacing was unsuccessful in four patients; in two of these four this was due to high atrial pacing thresholds. To date there has been no evidence of pacemaker perforation or pacemaker-induced coronary vein thrombosis. It is concluded that permanent pervenous atrial pacing from the coronary vein is a reliable method of atrial pacing without resorting to thoracotomy.

Permanent Pervenous Atrial Pacing From the Coronary Vein Long-Term Follow-Up

This report details our clinical experience during a 12 to 63 month follow-up period in 30 patients with permanent pervenous atrial pacemakers implanted in the coronary vein prior to May 1972. Indications for permanent atrial pacing included 20 patients with symptomatic sinus bradycardia, seven with atrial brady-tachy syndrome refractory to pharmacologic therapy, and three patients with atrial overdrive suppression for intractible ventricular arrhythmias. The average duration of atrial pacing was 29.2 + 2.4 (SEM) months, median 24 months. A bipolar electrode

Permanent Pervenous Atrial Synchronized Ventricular Pacing

Permanent pervenous atrial synchronized ventricular pacing was successfully accomplished in three patients. Atrial sensing was obtained from an electrode positioned in the coronary vein. Atrial electrograms with P waves greater than 1.5 mv were present in all three cases. Ventricular stimulation was accomplished through a separate electrode placed in the right ventricular apex. The left cephalic vein admitted both catheters, and the two electrodes were connected to an implantable P wave synchronized unit. The beneficial hemodynamic effects of atrial synchronized ventricular pacing were clinically evident. This new pervenous technique provides an optimal method of synchronized pacing in patients with heart block, intact sinoatrial activity and significantly compromised cardiac function.