Cardiac pacing in the 1980s: treatment and techniques in transition.

The pacemaker of the 1980s is designed to maintain atrioventricular synchrony through dual-chamber pacing. This pacemaker is multiprogrammable and capable of telemetric transmission of biologic, electronic and electrophysiologic data. Several developments have made this therapeutic modality possible: 1) the cumulative survival rate of many lithium-battery pacemakers exceeds 95% at 5 years; 2) lead and connector problems are rare; 3) atrial and ventricular electrode malfunctions occur in less than 2% of implants; and 4) new introducer techniques have simplified implantation (mortality and major morbidity rates are 0.5 and 0.4%, respectively). With multiprogrammability, pacemaker function can be optimized for the patient's needs, and about 20% of reoperations can be avoided. Ninety-six dual-chamber (DDD) pacemakers, 55 of which have been followed up for more than 3 months, have provided trouble-free performance and have yielded salutary clinical results, particularly when implanted to replace previous ventricular inhibited units. Problems with these pacemakers have included unusual pacing electrocardiograms, pacemaker eccentricities, programmer maintenance, pacing and follow-up complexities and costs. In the 1980s, effort will be required to find a balance between rapidly evolving technology and the clinical need for complex pacing systems. From 1978 to 1981, the rate of pacemaker implantation grew from 309 to 513 implants per million population per year, and there are now approximately 500,000 patients with implanted pacemakers living in the United States. Indications for pacing are ill-defined, because in many cases the assessment of clinical response to pacing is largely subjective, lacking satisfactory quantitative indexes. This decade will be a time of reappraisal of the extent of clinical applicability of new techniques, particularly the multiprogrammable dual-chamber system which, after 3 years of clinical trial, shows promise of being the predominant pacemaker of the immediate future.

Pacemaker-implantation complication rates: an analysis of some contributing factors.

An examination of 632 consecutive pacemaker implantations performed at a single institution by 29 implanting physicians over a 5 year period was made to determine which factors affected the 37 perioperative complications experienced. The introducer method of vein access contributed significantly to the complication rate, which was also related to the number of physician implanters on the staff and the makeup of the implantation teams. Of greatest interest was the substantially large incidence of complications experienced by implanters who performed fewer than 12 implantations per year, and particularly the incidence of lead-related complications.

The 1981 United States survey of cardiac pacing practices.

A survey of physicians implanting pacemakers was conducted to obtain a profile of permanent cardiac pacing practices in the United States during 1981. Questionnaires were mailed to 5,832 implanters with 765 responses (13%) received and 680 analyzed. It was estimated that there were approximately 5,600 physicians, 66% surgeons and 34% nonsurgeons, implanting pacemakers at 3,670 centers. About 118,000 new primary implants were performed, or 518 per million population. Only 17% of implantation procedures in 1981 were replacements compared with 31% in 1978. Roughly half the respondents worked in teams, most implanting from 46 to 55 pacemakers annually. The chief indications for permanent pacing were sick sinus syndrome (48%) and impairment of conduction in the atrioventricular node and His-Purkinje system (42%). Ninety-five percent of pacing leads were implanted transvenously. Seventy percent of the respondents had had experience with atrial and dual-chamber pacemakers, used largely to increase cardiac output. The use of ventricular demand (VVI) pacing decreased accordingly from 91% in 1975 to 84% in 1981. Although approximately 90% of primary pacemakers were programmable to some degree, almost half were not reprogrammed within the first 3 months after implantation and 30% were never reprogrammed. Most patients (85%) were followed up by transtelephonic electrocardiographic monitoring, 68% in conjunction with private office visits. The respondents estimated that dual-chamber pacing, accounting for 10% of implants in 1981, would increase to 37% by 1985. Early electrode malfunctions were less frequent when implantation was performed by high volume and solo implanters, and in public and community hospitals. It is concluded that periodic surveys of this type disclose important trends in the practice of cardiac pacing.

Deleterious effects of long-term single-chamber ventricular pacing in patients with sick sinus syndrome: the hidden benefits of dual-chamber pacing.

Nine hundred fifty patients who received three modes of primary pacemaker systems (581 dual-chamber universal [DDD], 84 atrioventricular-sequential ventricular-inhibited [DVI] and 285 ventricular-inhibited [VVI]) over 12 years were studied retrospectively to determine the effect of pacing mode on patient longevity and the subsequent development of chronic atrial fibrillation or flutter. All patients were followed up continuously for 7 to 8 years. Patients were classified according to indication for permanent pacing (sick sinus syndrome or other indication), age at pacemaker implantation (less than or equal to 70 or greater than 70 years) and history of atrial tachyarrhythmia. Fourteen percent of patients developed atrial fibrillation at some time during the study period. Of those, 4% had a DDD pacemaker, 8% had a DVI pacemaker and 19% had a VVI pacemaker. At 7 years, atrial fibrillation was significantly more frequent in the VVI group than in the DDD and DVI groups. In patients with sick sinus syndrome, the incidence rate was even higher in the VVI group but approximately the same in the DDD and DVI groups. Patients in the VVI and DVI groups who had had previous atrial tachyarrhythmia had a significantly higher incidence of atrial fibrillation at 7 years than did those in the DDD group. During the entire period there were 130 deaths in the study group, including 22% of patients with a DDD pacemaker, 38% of those with a DVI pacemaker and 50% of those with a VVI pacemaker. Patient survival at 7 years was lower in the VVI group than in the DDD or DVI groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Pacemaker lead extraction with the laser sheath: results of the pacing lead extraction with the excimer sheath (PLEXES) trial.

OBJECTIVES: The purpose of this study was to evaluate the safety and effectiveness of pacemaker lead extraction with the excimer sheath in comparison to nonlaser lead extraction. BACKGROUND: Fibrotic attachments that develop between chronically implanted pacemaker leads and to the venous, valvular and cardiac structures are the major obstacles to safe and consistent lead extraction. Locking stylets and telescoping sheaths produce a technically demanding but effective technique of mechanically disrupting the fibrosis. However, ultraviolet excimer laser light dissolves instead of tearing the tissue attachments. METHODS: A randomized trial of lead extraction was conducted in 301 patients with 465 chronically implanted pacemaker leads. The laser group patients had the leads removed with identical tools as the nonlaser group with the exception that the inner telescoping sheath was replaced with the 12-F excimer laser sheath. Success for both groups was defined as complete lead removal with the randomized therapy without complications. RESULTS: Complete lead removal rate was 94% in the laser group and 64% in the nonlaser group (p = 0.001). Failed nonlaser extraction was completed with the laser tools 88% of the time. The mean time to achieve a successful lead extraction was significantly reduced for patients randomized to the laser tools, 10.1 +/- 11.5 min compared with 12.9 +/- 19.2 min for patients randomized to nonlaser techniques (p < 0.04). Potentially life-threatening complications occurred in none of the nonlaser and three of the laser patients, including one death (p = NS). CONCLUSIONS: Laser-assisted pacemaker lead extraction has significant clinical advantages over extraction without laser tools and is associated with significant risks.

Identification of preoperative variables needed for risk adjustment of short-term mortality after coronary artery bypass graft surgery. The Working Group Panel on the Cooperative CABG Database Project.

OBJECTIVES: The purpose of this consensus effort was to define and prioritize the importance of a set of clinical variables useful for monitoring and improving the short-term mortality of patients undergoing coronary artery bypass graft surgery (CABG). BACKGROUND: Despite widespread use of data bases to monitor the outcome of patients undergoing CABG, no consistent set of clinical variables has been defined for risk adjustment of observed outcomes for baseline differences in disease severity among patients. METHODS: Experts with a background in epidemiology, biostatistics and clinical care with an interest in assessing outcomes of CABG derived from previous work with professional societies, government or academic institutions volunteered to participate in this unsponsored consensus process. Two meetings of this ad hoc working group were required to define and prioritize clinical variables into core, level 1 or level 2 groupings to reflect their importance for relating to short-term mortality after CABG. Definitions of these 44 variables were simple and specific to enhance objectivity of the 7 core, 13 level 1 and 24 level 2 variables. Core and level 1 variables were evaluated using data from five existing data bases, and core variables only were examined in an additional two data bases to confirm the consensus opinion of the relative prognostic power of each variable. RESULTS: Multivariable logistic regression models of the seven core variables showed all to be predictive of bypass surgery mortality in some of the seven existing data sets. Variables relating to acuteness, age and previous operation proved to be the most important in all data sets tested. Variables describing coronary anatomy appeared to be least significant. Models including both the 7 core and 13 level 1 variables in five of the seven data sets showed the core variables to reflect 45% to 83% of the predictive information. However, some level 1 variables were stronger than some core variables in some data sets. CONCLUSIONS: A relatively small number of clinical variables provide a large amount of prognostic information in patients undergoing CABG.

Permanent pacing of the heart: 1952 to 1976.

The theory and science of electrical pacing of the heart is scarcely 2 decades old, but developments in these areas have in a way revolutionized modern cardiology. This report, basically a review of the major developments during that time, describes the present state of the art, and calls attention to the many people who have brought us to this point. Results of a recent national survey reveal that about 156,000 patients in the United States are living with implanted pacemakers or about 1 in every 1,300 persons. The rate of new implants is 270/million each year, the highest in the world. The impact of such a volume is considerable, affecting industrial growth, federal legislation and control, insurance plans and a multitude of medical programs. New power sources, some touted to last a lifetime, will have a great impact but will not change the current state of the art materially because 30 percent or more of pacemaker operations are for problems other than routine battery exhaustion. The need for improvements in other pacemaker components is emphasized.

Survey of cardiac pacing in the United States in 1989.

A survey of physicians who implant permanent cardiac pacemakers was conducted to identify practice patterns related to pacemaker-implantation frequency, hospital and implantation-facility characteristics, indications for pacing and pulse-generator replacement, preferences regarding device types, pacing modes, follow-up methods and frequency, and type and frequency of pacing-related complications. Questionnaires were sent to 11,414 potential physician respondents and 6 pacemaker manufacturers. Implanters' opinions were solicited regarding such issues as the importance of various device features and capabilities, the appropriateness of practice guidelines, and the efficacy of quality-assurance measures. In 1989, 89,445 primary pacemaker implantations and 21,055 pulse-generator replacements were performed by approximately 7,919 physicians at about 3,400 U.S. centers. Typically, a pacemaker manufacturer's sales representative played an active role in 80% of cases. Since the last survey, which examined pacing practices in 1985, primary implantations of dual-chamber pacemakers increased from 22 to 32%, and the proportion of adaptive-rate pacemakers increased from 1 to 40% of primary implants. The "typical" implanter used bipolar electrode systems in 90% of cases, single-chamber pacemakers in 70%, and the introducer method in 95% of lead placements. Significant differences in practice patterns were found among subsets of the survey respondents. Surgeons tended to work alone, use simpler, single-chamber pacemakers, and leave follow-up to others. Electrode stability tended to be better among implanters in nonacademic environments. The quadrennial survey continues to provide useful information on an easily identifiable and traceable patient population, but the process would be greatly simplified by the adoption of a "universal" reporting system such as that used in Europe.

Survey of cardiac pacing and defibrillation in the United States in 1993.

A survey of implanters of permanent cardiac pacemakers and implanted cardioverter-defibrillators (ICDs) in the United States during 1993 was conducted to identify present and changing patterns in indications for pacing implantation techniques, pacing-mode selection, follow-up, and opinions regarding pacing-and ICD-related issues. Five major pacemaker manufacturers also provided estimates of the numbers of pacemakers and ICDs implanted in the United States from 1990 through 1993. In 1993 approximately 133,000 new rhythm-management devices, including 112,000 primary pacing systems and 16,000 ICDs, were implanted, an increase of 18% for pacemakers and 113% for ICDs since 1990. In 1993, pacemaker implantations were performed by about 8,700 physicians working in 3,300 hospitals and 1,000 independent "surgi-centers." Since the last survey, which addressed pacing practices in 1989, respondents' use of dual-chamber pacemakers increased from 32% to 68% of the total, and adaptive-rate systems from 29% to 48%. Significant differences (p <0.05) were found among subcategories of implanters and among complications encountered in different circumstances. Surgeons tended be the older and more experienced implanters, but used a smaller proportion of active-fixation leads, dual-chamber systems, and adaptive-rate pulse generators, and tended to rely more heavily on a pacemaker manufacturer's representative in operative and follow-up procedures. Complications were more common with bipolar leads, with leads implanted by means of an introducer, and with passive-fixation ventricular leads. The survey provided useful insights into trends and differences in pacemaker and defibrillator practice. Future surveys would be facilitated if a standardized implant registry such as that used in Europe were established in the United States.

Cardiac pacing practices in the United States in 1985.

Physicians active in pacemaker implantation and follow-up were surveyed to obtain a profile of permanent cardiac pacing practices in the United States during 1985. Questionnaires were sent to 628 physicians, mainly in New Jersey; 145 responses were received and analyzed. A separate questionnaire was sent to 9 pacemaker manufacturers to solicit information concerning the volume of pacemaker sales and their opinions on a variety of subjects. The rate of permanent pacemaker implantation declined for the first time: it dropped from 518 devices per million population in 1981 to 374 in 1985. Sinus node dysfunction was the chief indication for permanent pacing in 52% of primary implantations; conduction disorders of the atrioventricular node and His-Purkinje system accounted for 41% and ventricular tachyarrhythmias for 2%. Dual-chamber pacing modes were used less frequently than was predicted in 1981, accounting for 30% of primary and 19% of replacement pacemakers. More than 43% of programmable pulse generators were never reprogrammed after implantation. Surveys such as this continue to provide useful information despite obstacles encountered in the use of questionnaires. Important differences in practice patterns and outcomes were identified between surgeons and nonsurgeons, and between frequent and infrequent implanters. These differences reinforce the suggestion that implanters should work at a volume sufficient to maintain their expertise, and that cooperation between surgeons and nonsurgeons would lead to improvements in patient selection, surgical results and optimal pacemaker programming and follow-up care. Better results could be achieved by adopting the continent-wide system of a pacemaker registry now used in Eastern Europe and Great Britain.

Method for the rapid and atraumatic insertion of permanent endocardial pacemaker electrodes through the subclavian vein.

One hundred sixty-four permanent pacemaker implantations through the subclavian vein were accomplished by 17 different physicians at four institutions utilizing a specially constructed peel-away introducer. Fourteen attempts (8.3 percent) to cannulate the subclavian vein were unsuccessful. There were four cases of pneumothorax (2.4 percent) and two cases of hematoma formation (1.2 percent). The procedure has the advantage of a rapid and atraumatic insertion of a variety of transvenous pacemaker electrodes, and the avoidance of surgical dissection for a venous entrance site.

The nuclear pacemaker: is renewed interest warranted?

From 1973 through 1987, 155 radioisotope-powered "nuclear" pacemakers were implanted in 132 patients at the Newark Beth Israel Medical Center. The longevity of the first 15 devices, all of which were fixed-rate (VOO) pacemakers, was significantly better than that of 15 lithium-chemistry demand (VVI) pacemakers used as control devices (p = 0.0002). Of the entire cohort of 155 nuclear pacemakers, 136 were VVI devices and 19 were VOO units. The patients with VOO pacemakers needed reoperations more often than did those with VVI pacemakers, chiefly for mode change (p less than 0.001). Power-source failure was observed in only 1 case, but 47 nuclear pacemakers were removed for other reasons, including component malfunction (15 units), mode change (12 units), high pacing thresholds (8 units) and lead or connector problems (5 units). The actuarial survival at 15 years was 99% for power sources and 82% for the entire pacing systems (pulse generators plus leads). The frequency of malignancy was similar to that of the population at large and primary tumor sites were randomly distributed. Deaths most commonly were due to cardiac causes (68%). Thus, nuclear pacemakers are safe and reliable and their greater initial cost appears to be offset by their longevity and the resulting decrease in the frequency of reoperations. It is reasonable to suggest that further use be made of long-lasting nuclear power sources for modern pacemakers and other implantable rhythm-management devices.

Usefulness of an implantable antitachycardia pacemaker system for supraventricular or ventricular tachycardia.

The Cordis Omni-Orthocor model 234A, an implantable antitachycardia system, was evaluated in 13 patients. Two patients had recurrent sustained supraventricular tachycardia (SVT) and 11 had ventricular tachycardia (VT). The system was used for SVT or VT termination (group 1: SVT, 2 patients; VT, 4 patients) or for demand pacing and noninvasive electrophysiologic studies for tachycardia induction and serial electrophysiologic testing alone (group 2: VT, 7 patients). The overdriver was used successfully in 4 of 6 patients in group 1 for repeated tachycardia termination (SVT and VT) during a mean follow-up period of 18 months. One patient had 1 sustained VT episode unresponsive to pacing and 1 patient had no recurrence of tachycardia. Tachycardia termination zones varied when using the system in 2 patients receiving long-term amiodarone therapy. Eighteen noninvasive electrophysiologic studies for serial drug testing were performed, 4 in group 1 and 14 in group 2. Clinical tachycardia was induced and successfully terminated by use of the overdriver in 12 studies. It is concluded that implantable antitachycardia systems can be used successfully for noninvasive tachycardia induction and termination and for reliable serial electrophysiologic studies. Such systems provide improved patient safety and acceptability and are reasonable in cost.

Symptomatic unilateral cannon "a" waves in a patient with a ventricular pacemaker.

A 64-year-old woman was referred because of intermittent pulsations of the left side of the neck, face, and scalp that were first noticed after the insertion of a ventricular pacemaker. The pacemaker had been inserted because of symptomatic 2:1 atrioventricular block. Right cardiac catherization showed cannon "a" waves, and phlebographic studies revealed stenosis of the right innominate and internal jugular veins. The symptoms were abolished by conversion to an atrial synchronous pacing system. Comments are offered on the hemodynamic findings, the "pacemaking syndrome", and the use of atrial synchronous pacing.

Meralgia paresthetica after coronary bypass surgery.

Meralgia paresthetica is a neurologic disorder characterized by localized paresthesia and numbness on the anterolateral aspect of the thigh and involving the lateral femoral cutaneous nerve. It involves no motor deficits. Meralgia paresthetica, which may result from a variety of causes, has been observed as a rare complication in heart operations. Its cause when associated with such operations is uncertain but may be prolonged relaxed positioning on the operating table and recovery room stretcher. Another possible cause of meralgia paresthetica after heart operations is the "frog-leg" position of the legs during vein harvesting. Patients with this condition should be advised of its untreatable, but benign and self-limiting, nature.

Coronary artery bypass grafting in patients with ejection fractions below forty percent. Early and late results in 466 patients.

The outcome of patients undergoing coronary artery bypass grafting with preoperative ejection fractions below 40% was evaluated to determine if a specific level of ventricular dysfunction resulted in unacceptably poor short-term or long-term survival rates. Left ventricular ejection fractions were segregated into groups of five percentage points each starting from 35% to 39% and progressing down to 10% to 14%. In evaluating the six ejection fraction groups between 10% and 39%, we found no significant differences among them with regard to previous myocardial infarctions, left ventricular end-diastolic pressure (LVEDP), age, preoperative New York Heart Association (NYHA) class, or number of vessels bypassed. Eighty-four percent were men and 16% women. From 1976 through 1982, 466 patients were distributed among these groups, all having ejection fractions below 40% (mean 30% +/- 3% SEM). There were significant differences (p = 0.001) in both the hospital and long-term survival (36 months) of patients with preoperative ejection fractions from 20% to 39% (425 patients) as compared to those with preoperative ejection fractions from 10% to 19% (41 patients). Hospital survival rate was 89% for patients with ejection fractions from 20% to 39% but only 63% for patients with ejection fractions below 20%. Similarly, at 3 years, patients with ejection fractions of 20% to 39% had an average survival rate of 60% as compared to an average survival rate of 15% for those with ejection fractions below 20%. Neither the preoperative LVEDP nor the intraoperative ischemic arrest time significantly predicted survival. In all survivors, NYHA class decreased from an average of 3.00 to 1.25 in surviving patients following bypass at a mean follow-up of 29 +/- 5 months. It is concluded that ejection fraction is an excellent predictor of short-term and long-term survival following coronary artery bypass grafting. Patients with ejection fractions of 10% to 19% have a significantly reduced short-term and long-term survival rate as compared to patients with ejection fractions of 20% or more.

Preliminary experience with the use of a programmable pacemaker.

One hundred sixty-four patients, in whom new externally programmable pacemakers had been inserted, were studied over a two year period, beginning July, 1972. Following implantation, the rate and current output of this pacemaker could be changed at any time by a non-invasive technique involving electromagnetic pulse trains emitted by an external "programmer". In 89 percent of the patients it was possible to reduce battery output by half, implying greater longevity of the pacer in these cases. In 15 percent of the patients, manipulative control of the pacemaker rate was employed and found beneficial.

Coronary angioplasty versus coronary bypass. Three-year follow-up of a matched series of 250 patients.

Two hundred fifty consecutive patients treated for one or two vessel coronary artery disease with either balloon angioplasty or surgical bypass were monitored for 3 years in a study designed to determine the comparative long-term effectiveness of each treatment. The 125 patients having angioplasty were matched with the 125 patients having bypass, so that both groups had a similar number of patients with single or double vessel disease. The two groups did not significantly differ in age, male:female ratio, New York Heart Association class, or risk factors. The ejection fraction was 54 +/- 11 in the angioplasty group and 49 +/- 12 mmHg in the surgical patients (p = 0.0031). Angioplasty was deemed initially successful in 88% (110/125), unsuccessful in 10% (12/125), and in 2% (3/125) the lesion could not be crossed. Emergency bypass was performed in 10% (12/125). Four of the 125 angioplasty patients (3%) died within 30 days. Coronary artery bypass grafting was successfully performed on the matched set of surgical patients with 99% (124/125) discharged well. There was one (1%, 1/125) surgical death. The average hospital stay per patient was 4.8 +/- 3.1 days for angioplasty and 12.1 +/- 4.2 days for bypass grafting (p = 0.0000). Three-year postprocedure follow-up was obtained on 96% (236) of the 245 patients discharged alive. A second angioplasty was required in 18%, and 11 angioplasty patients subsequently required surgical bypass. Overall, 19% (23/121) of the angioplasty patients ultimately required bypass. Four late deaths occurred in the angioplasty group, which brought the early and late mortality rates to 7% (8/121). There were two late surgical deaths, which brought the combined surgical mortality to 2.5% (3/120), p = 0.1263. Patient evaluation reveals that 63% (76/121) of the angioplasty group are alive and in New York Heart Association class I or II 3 years after one or two angioplasty procedures. This figure compares with 92% (110/120) of surgical patients alive and in the same two New York Heart Association classes (p = 0.0000).

Timing of coronary revascularization after acute myocardial infarction. Early and late results in patients revascularized within seven weeks.

Evidence of ischemia after acute myocardial infarction is a serious complication. If angiography reveals significant coronary artery disease, the precise timing of myocardial revascularization may be of critical importance. From 1978 through 1982, 174 patients underwent myocardial revascularization within 7 weeks of a documented myocardial infarction. The male:female ratio was 138:36, the average age was 58 +/- 1 (SEM) years; and the ejection fractions averaged 41% +/- 1%. Forty-four (25%) patients required preoperative intra-aortic balloon pump support, and an additional 18 (10%) required intra-aortic balloon pumping to be separated from cardiopulmonary bypass. An average of 2.9 +/- 0.1 vessels per patient were bypassed. The hospital mortality for these 174 patients was 16%. When mortalities were categorized according to the postinfarction week in which operation was performed, hospital mortality fell from 46% for those patients operated upon within 1 week of infarction to 6% for those patients operated upon 7 weeks after infarction. Of those patients operated upon within the first week after infarction, 23% were in cardiogenic shock and 62% required preoperative balloon pumping. Clearly the most critically ill patients were operated upon during the early postinfarction period. However, there was a marked difference in survival when patients in each of the seven weekly groups were classified according to ejection fraction. All patients with an ejection fraction greater than or equal to 50% (50 patients) operated upon at any time after infarction survived their hospital course, with only one late death. Conversely, among the 124 patients with an ejection fraction less than 50% operated upon during this 7 week interval, there were 27 (22%) hospital deaths. In this latter group, survival rates steadily improved if revascularization was performed at a time more remote from the infarction. The difference in early and late survival rates of patients operated upon with an ejection fraction greater than or equal to 50% compared to patients with an ejection fraction less than 50% is highly significant (p less than 0.001). We conclude that myocardial revascularization is safe at any time after myocardial infarction for those individuals with an ejection fraction greater than or equal to 50%. However, if the ejection fraction is less than 50%, then operation after myocardial infarction should be delayed at least 4 weeks.

Emergency operation after failed angioplasty.

A group of patients with failed angioplasty who then required emergency coronary bypass was compared with a historically matched group of patients who had had elective bypass grafting. The two groups were well matched in age, sex, ejection fraction, and New York Heart Association classification and in the incidence of diabetes and hypertension. Significant differences were found in the prevalence of mortality (12% versus 1.5%), hemorrhage (28% versus 13%), cardiac tamponade (10.5% versus 1.5%), myocardial infarction (28% versus 9%), and length of hospital stay (15.3 days versus 13.4 days). Cardiogenic shock carries the worst prognosis; four of the five patients with this condition died. Because emergency operation after failed angioplasty carries with it significant postoperative morbidity and mortality, this procedure cannot be considered equivalent to elective coronary bypass grafting.