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Natural History Following Ventricular Pacemaker Implantation

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Natural History Following Ventricular Pacemaker Implantation Symptomatic Brady arrhythmias in the Adult: Natural History Following Ventricular Pacemaker Implantation ARTHUR B. SIMON and NANCY JANZ From the Departments of Internal Medicine, Division of Cardiology and Nursing Services of the University of Michigan Medical Center, Ann Arbor, Michigan SIMON, A.B., AND JANZ, N.: Symptomatic bradyarrhythmias in the adult: natural history following ventricular pacemaker impiantation. The preimplantation arrhythmias, coexistent medical condi- tions, the causes of death, and survival course are described for 399 patients who received their initial ventricuJar pacemaker impiantation for a bradyarrhythmia (AV block, sinus node disease, and hyper- sensitjVe carotid sinus syndrome] at the (Jniversity of Michigan from 1961 to 1979. Factors which corre- lated with a poor survival are elucidated. Survival for those with sinus node disease was virtually identi:;al to those with AV block, with only 63% surviving over jive years. Advanced age and conges- tive heart failure prior to implantation, and underlying ischemic or hypertensive heart disease por- tended a poorer survival in both groups. Patients with hypersensitive carotid sinus syndrome had a distinctly better prognosis—no deaths occurred until (he eighth year after pacing. Patients with no underlying heart disease and those with valvular disease did remarkably better than those with an ischemic or myopathic etiology. Apparent progression or complications of the underlying heart dis- ease v/as the major cause of mortality. Sudden death, congestive heart failure, myocardial infarction, and major arrhythmias were the causes of death in 48% of those who died. Implications of improved pacing modalities an late complications and death are discussed. (PACE, Vol. 5, iVlay-June, 1982] bradyarrhythmias, ventricular pacemaker For nearly two decades permanenl pacemakers processor technology, have resulted in smaller, have been the treatment of choice for high longer lasting, and improved pacing devices. grade atrioventricular block. Sinus node dis- This has enabled the clinician to normalize car- ease and other bradyarrhythmias have been diac function more completely through reten- recognized with increasing frequency, so that tion of atriovenlricular synchrony and to make now in the United States, patients with these lat- periodic adjustments in pacing system perfor- ter disorders constitute 30-50% of all patients re- mance which might reduce late morbidity and ceiving their initial pacemaker implantation. Al- mortality. In addition, as a result of these more though initially pacemaker implantation was physiologic pacing modes, the longevity and considered an investigative procedure per- quality of life of these patients with bradyar- formed only at a few university centers, these rhythmias may be substantially improved over implants are now performed with acceptable that achieved with ventricular pacing alone. It complication rates by adequately trained per- seems germane, therefore, to summarize the sonnel at many community hospitals world- current status of patients with symptomatic wide. bradyarrhythmias treated over the previous two Within the last few years improvements in decades with ventricular pacing in order to 1) power sources and leads, as well as micro- describe survivorship and causes of late mor- tality; 2) to identify those conditions in the pa- tient population which correlate with a poor Addrefs for reprints: Arthur B. Simon. M.D.. 3200 Burnet Avenue, Cincjinnati. Ohio 45229 prognosis; 3) to enumerate the causes of late morbidity and mortality; and 4) to discuss how Received July 15,1981; revision received August 18,1981; ac- cepted August 18, 1981. improvements in pacing system technology 372 May-June 1982 PACE, Vol. 5 BRADYARRYTHMIAS FOLLOWJNC VENTR1CUJ.AR PACEMAKER IMPLANTATION might improve survival. Data of this type would Determination of the Cause of Death appear to be necessary in order to measure accurately any effects future technology may Details concerning the circumstances of death have on this patient population. were obtained by interview with family members, the patient's physician, and other in- Methods formed witnesses. All available medical rec- ords including autopsy data were reviewed Patient Selection whenever possible. Mortality data on deaths The records of all adult patients who re- after 1972 were collected within six weeks of ceived their initial permanent pacemaker im- death, while data on those who died prior to plantation at the University of Michigan were 1972 were obtained, in part, retrospectively. reviewed. These patients have been the sub- Sudden death was defined as death within one jects of several previous reports from this insti- hour after the onset of symptoms. Death due to tution on indications, techniques, and complica- myocardial infarction was based on a definite tions of implantation and natural history of pa- history of sustained typical ischemic precordial tients wilh permanent pacemakers.'"'" This re- chest pain and other symptoms which termi- port continues follow-up observations to De- nated in death and whenever possible, supple- cember 31, 1979 for all patients receiving their mented by ECG, enzyme, or autopsy confirma- initial pacemaker implant prior to April 1, 1979. tion. Congestive heart failure was diagnosed by Data on past history, the indication for pace- the criteria of McKee.'" For the purposes of this maker placement, subsequent clinical course, report, only adults (over age 21) were included and complications were summarized and the whose indication for pacing was a bradyar- data transferred to computer tape. Data were rhythmia. Experience with children with per- analyzed using standard statistical methods. The manent pacemaker implants from this institu- MIDAS," and IGSAS'- data analysis systems tion will be reported upon elsewhere.'" A few were utilized. Differences between groups were adults paced for ventricular tachyarrhythmias analyzed by chi squared method, and survival in the mode of "overdrive" suppression, and one was determined by the life table method.''•'•' The patient paced with an antitacbycardia device Breslow's generalized Kruskal-Wallis Test was are not included in this report. Since 1965, pa- utilized to determine if the survival distribution tients were followed in a pacemaker clinic no differed across strata for any single preim- less frequently tban every six months. For the plantation variable.'^ patients who were followed outside the institu- The etiology of underlying heart disease for tion, telephone or written reports on cardiovas- patients in this series was based on the avail- cular status were obtained annually. During the able clinical data at the time of diagnosis of the follow-up interval patients were paced with bradyarrhythmia, Electrocardiographic criteria General Electric* Medtronic,** Cordis.f and alone were used for classification of subgroups; CPI:|: pacing systems. electrophysiologic studies were employed in only a few patients after 1972. Criteria for ad- Results mission into each etiologic category were similar to that previously described [e.g.. whether the Description of the Population apparent underlying heart disease was arterio- sclerotic. hypertensive, rheumatic, congenital, The 399 adult patients included in this report valvular, or due to a cardiomyopathy).'' Patients were divided into three categories according to were considered to have "idiopathic conduc- their specific bradyarrhythmia. The indication tion system disease" if there was no underlying valvular, myocardial. arteriosclerotic or hyper- tensive disease, and heart size was normal or 'General Eleclric, Milwaukee, Wisconsin. U.S.A. •'Medtronic, Inc., Minneapolis, Minnesota, U.S.A. nearly so, without congestive heart failure at in- fCordis Corp., Miami, Florida, U.S.A. itial implantation. :j:Cardiac Pacemakers, Inc., Si. Paul. Minnesota, U.S.A. PACE. Vol. 5 May-lune 1982 373 SIMON AND JANZ for pacing and age distrihution for the patients is orders—but the group with hypersensitive ca- shown on Figure 1. There were 312 patients with rotid sinus syndrome was younger. The sinus atrioventricular block (AVBl, 75 patients with node group had a larger percentage with isch- sinus node disorders (SND), and 12 patients with emic heart disease and less with aortic valve dis- hypersensitive carotid sinus syndrome [HCSS], ease. Hypertension, congestive heart failure, In this population, 44% had no apparent heart cerebrovascular disease, diabetes, chronic renal disease at the time of their initial implant, 30% disease, cancer, and obstructive lung disease had ischemic heart disease. Valvular heart dis- were common in the study sample [Table II). ease was present in 1B%, and congenital heart There were no significant differences in the pre- disease in 2% (Table I). One patient had a bullet valence of the specified associated illnesses in wounc to the heart resulting in AV block, and the three bradyarrhythmia categories. The AV one patient had leukemia and intermittent block group had a higher prevalence of cardio- sepsis, either one of which may have been re- megaly, possibly corresponding to a higher prev- sponsible for AV block. Approximately one- alence of hypertension. Diabetes mellitus was third of the patients were under the age of 65, very prevalent in all categories and far more one-third were 65-74. and one-third over age 75 common than in age matched controls, as has at the time of initial pacemaker implantation been previously reported.""'" Within the sinus [Table
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