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ABSTRACTS SERIAL EXERCISE TESTING UP TO 5 YEARS AFTER BYPASS SURGERY IN GROUPS WITH DIFFERENT DEGREES OF REVASCULARIZATION Helmut Gohlke, MD, Christa Gohlke-B&wolf, MD, Ladislaus Samek, MD, Peter Stiirzenhofecker, MD, Martin Schmuziqer,MD, _ Helmut Roskamm, MD, FACC, Rehabilitationszentrum fur Herz- und Kreislaufkranke Bad Krozingen, FRG There is little data available on how long objective impro- vement of exercise (Ex) parameters is maintained after by- pass surgery (BPS) and how it correlates with the angicgra- phically determined degree of revascularization (REV). EX tests of 417 pts were reviewed who had undergone BPS under age 56 and angiography 1 year postop. One preop Ex test and an average of 3 postop Ex tests were performed during the 1 to 5 year follow-up. Pts with 3 different degrees of REV are compared: REV I: All> 50% stenosed vessels are pr@ vided with an open graft. P.EV II: The main vessel supplying the LV is provided with an open graft. REV III: The main vessel supplying the LV is not provided with an open graft but at least 1 additional graft is patent. The percentage of pts with&O_1 mV ST-segment depression (%STS), the an- gina-free EX tolerance (AFET) in watts and the maximal double product (HRxBP) are recorded. Results: PreoP - 3 yrs postop - - 5 yrs postop - REV I II III I II III n 417 112 101 33 50 27 5 % sn 77% 20@ 329 45%' 32%1 40%: 60%# AFET 41+34 81+51r 62234 50f50# 71f5c 66*44' 55+68# HRxBP 187*53 248+74t238*6C1210*47# 242+-7T229+-60'201*68# Xl@' meankandard deviation; all p-values compared to preop rp<0.0005, *pLO.O05, #=I& significant Conclusion: At 3 and 5 yrs postop, only pts in groups I and II show significant improvement of all Ex parameters. Thus the completeness of REV is an important determinant for the longterm improvement of postop EX parameters up to 5 years after surgery. EFFECTS OF CORONARY BYPASS SURGERY VERSUS MEDICAL THERAPY ON WALL MOTION AENORMALITIES AT 5 YEARS. John McAnulty, MD, FACC, Cynthia Morris, MPH, Frank Kloster, MD, FACC, Josef Rosch, MD, J. David Bristow, MD, FACC. Oregon Health Sciences University, Portland, Oregon. After random assignment to surgical (S, n=51) and medi- cal (M, n=49) therapy, the effect of coronary bypass sur- gery on left ventricular (LV) wall motion abnormalities (WMA) was evaluated prospectively. Followup angiograms were performed at an average of 61 months in 26 S patients (range 47 to 78 mos) and 19 M patients (44 to 69 mos). The 2 groups studied at 5 years did not differ initially (p=NS) in age, sex, previous myocardial infarction (MI), severity of coronary disease, ejection fraction (EF) or in location, type or number of WMA (37 of 78 segments, 47% in S; 22 of 56 segments, 39% in M). Graft patency was 71% at 5 years. Interval MI occurred in 6 S and 2 M. WMA improvement in S segments with patent grafts (18/27 segments, 67%) was greater than in M patients (7/21 seg- ments, 33%) (pcO.05). When all S-WMAsegments were con- sidered, the difference in improvement persisted (26/37 segments, 70%). Six WMA segments improved despite graft occlusion to that segment. WMA worsened in 2137 (5%) S segments versus 3i21 (14%) M segments (p=NS). New WMA in initially normal segments developed in lo/41 (24%) in S and 8/35 (23%) in M (p=NS). Mean EF was similar initially in S and M and did not change for either group studied at 5 years (S: 0.60 to 0.62; M: 0.64 to 0.62; p=NS). Improvement in WMA occurred nore frequently with S than with M therapy. This was not always attributable to graft patency. New WMA may develop despite S or M therapy. Change in segmental LV wall motion is not reflected in global LV performance as characterized by EF. MONDAY, APRIL 26, 1982 PM ATRIAL ARRHYTHMIAS I AND II 4:00-5: 15 ENTRAINMENT OF “ECTOPIC ATRIAL TACHYCARDIA”: EVIDENCE FOR RE -ENTRY. Richard W. Henthorn, MD; Vance J. Plumb, MD, FACC; Joaquin G. Arciniegas, MD; Albert L. Waldo, MD, FACC. Division of Cardiology, University of Alabama in Birmingham, Birmingham, Alabama. The mechanism of “ectopic atria1 tachycardia” (EAT) is generally thought to be automatic. We studied fourteen patients with sixteen episodes of ectopic atria1 tachy- cardia with rapid atria1 pacing. Eight patients demon- strated entrainment during rapid atria1 pacing. The average atria1 cycle length of these eight patients was 306 msec (range 260 msec to 400 msec) and all demonstrated the presence of AV block without interruption of the tachycardia sometime during their study. Rapid atria1 pacing was initiated at or slightly above the ectopic atria1 tachycardia atria1 rate and incrementally increased until interruption of the arrhythmia occurred. Transient entrainment was manifest as: (a) acceleration of the ec- topic atria1 tachycardia during rapid atria1 pacing to the pacing rate, (b) constant atria1 fusion during atria1 pacing, (c) return of the ectopic atria1 tachycardia to its original atria1 rate without interruption upon dis- continuation of the pacing, and (d) absence of overdrive suppression (i.e. the first return atria1 cycle after termination of pacing and subsequent atria1 cycle length not exceeding the original ectopic atria1 tachycardia atria1 cycle length). Thus, in this study group, many patients with ectopic atria1 tachycardia demonstrated transient entrainment, a finding which strongly suggests a re-entrant rather than an automatic mechanism. ELECTROPHYSIOLOGY OF LONE ATRIAL FIBRILLATION Ross J. Simpson, Jr., ;l.O., James R. Foster, il.0.. Leonard S. Gettes, X.D., University of North Carolina, Chapel Hill. N.C. Factors contributing to the initiation of atria1 fibrillation in patients with normal hearts are poorly uncierstood. To test the hypothesis that these patients have abnormalities of atria1 excitability and conduction we measured atria1 strength interval curves to study re- fractoriness, late diastolic threshold and conduction times of early and late premature beats in four patients with recurrent atria1 fibrillation (AF) in the absence of heart disease and six control (C) patients. All ten patients had normal left atria1 size by echocardiography and normal P wave duration on the electrocardiogram. Hone had cardiomegaly, failure, preexcitation or abnor- malities of sinus node function. Conduction times were measured from the high right atrium to the low septal right atrium (AHRA-AHIS) and to the coronary sinus (AHRA-ALA). ~_ There were no significant differences between AF and C patients in P wave duration, left atria1 size, the con- duction time of premature beats in late diastole or late diastolic threshold. In AF patients the functional refractory period was shorter (270 + 35 vs 310 ? 25 ms, p < .05) and the amount of conduction slowing of early premature beats was greater (AHR -AHIS: 30 i 15 vs 10 * 5 ms. p < .Ol; AHRA-A A: 35 f eo vs 5 + 5 p < .Ol). The factors responsibl: for these differences are not known. However, our results indicate that patients with lone atria1 fibrillation have abnormalities of atria1 refractoriness and conduction which may explain their propensity to atria1 fibrillation. 920 March 1982 The American Journal of CARDIOLOGY Volume 49

Electrophysiology of lone atrial fibrillation

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ABSTRACTS

SERIAL EXERCISE TESTING UP TO 5 YEARS AFTER BYPASS SURGERY IN GROUPS WITH DIFFERENT DEGREES OF REVASCULARIZATION Helmut Gohlke, MD, Christa Gohlke-B&wolf, MD, Ladislaus Samek, MD, Peter Stiirzenhofecker, MD, Martin Schmuziqer,MD, _ Helmut Roskamm, MD, FACC, Rehabilitationszentrum fur Herz- und Kreislaufkranke Bad Krozingen, FRG

There is little data available on how long objective impro- vement of exercise (Ex) parameters is maintained after by- pass surgery (BPS) and how it correlates with the angicgra- phically determined degree of revascularization (REV). EX tests of 417 pts were reviewed who had undergone BPS under age 56 and angiography 1 year postop. One preop Ex test and an average of 3 postop Ex tests were performed during the 1 to 5 year follow-up. Pts with 3 different degrees of REV are compared: REV I: All> 50% stenosed vessels are pr@ vided with an open graft. P.EV II: The main vessel supplying the LV is provided with an open graft. REV III: The main vessel supplying the LV is not provided with an open graft but at least 1 additional graft is patent. The percentage of pts with&O_1 mV ST-segment depression (%STS), the an- gina-free EX tolerance (AFET) in watts and the maximal double product (HRxBP) are recorded. Results:

PreoP - 3 yrs postop - - 5 yrs postop - REV I II III I II III n 417 112 101 33 50 27 5 % sn 77% 20@ 329 45%' 32%1 40%: 60%# AFET 41+34 81+51r 62234 50f50# 71f5c 66*44' 55+68# HRxBP 187*53 248+74t 238*6C1210*47# 242+-7T 229+-60'201*68# Xl@' meankandard deviation; all p-values compared to preop

rp<0.0005, *pLO.O05, #=I& significant Conclusion: At 3 and 5 yrs postop, only pts in groups I and II show significant improvement of all Ex parameters. Thus the completeness of REV is an important determinant for the longterm improvement of postop EX parameters up to 5 years after surgery.

EFFECTS OF CORONARY BYPASS SURGERY VERSUS MEDICAL THERAPY ON WALL MOTION AENORMALITIES AT 5 YEARS. John McAnulty, MD, FACC, Cynthia Morris, MPH, Frank Kloster, MD, FACC, Josef Rosch, MD, J. David Bristow, MD, FACC. Oregon Health Sciences University, Portland, Oregon.

After random assignment to surgical (S, n=51) and medi- cal (M, n=49) therapy, the effect of coronary bypass sur- gery on left ventricular (LV) wall motion abnormalities (WMA) was evaluated prospectively. Followup angiograms were performed at an average of 61 months in 26 S patients (range 47 to 78 mos) and 19 M patients (44 to 69 mos). The 2 groups studied at 5 years did not differ initially (p=NS) in age, sex, previous myocardial infarction (MI), severity of coronary disease, ejection fraction (EF) or in location, type or number of WMA (37 of 78 segments, 47% in S; 22 of 56 segments, 39% in M). Graft patency was 71% at 5 years. Interval MI occurred in 6 S and 2 M.

WMA improvement in S segments with patent grafts (18/27 segments, 67%) was greater than in M patients (7/21 seg- ments, 33%) (pcO.05). When all S-WMA segments were con- sidered, the difference in improvement persisted (26/37 segments, 70%). Six WMA segments improved despite graft occlusion to that segment.

WMA worsened in 2137 (5%) S segments versus 3i21 (14%) M segments (p=NS). New WMA in initially normal segments developed in lo/41 (24%) in S and 8/35 (23%) in M (p=NS).

Mean EF was similar initially in S and M and did not change for either group studied at 5 years (S: 0.60 to 0.62; M: 0.64 to 0.62; p=NS).

Improvement in WMA occurred nore frequently with S than with M therapy. This was not always attributable to graft patency. New WMA may develop despite S or M therapy. Change in segmental LV wall motion is not reflected in global LV performance as characterized by EF.

MONDAY, APRIL 26, 1982 PM ATRIAL ARRHYTHMIAS I AND II 4:00-5: 15 ENTRAINMENT OF “ECTOPIC ATRIAL TACHYCARDIA”: EVIDENCE FOR RE -ENTRY. Richard W. Henthorn, MD; Vance J. Plumb, MD, FACC; Joaquin G. Arciniegas, MD; Albert L. Waldo, MD, FACC. Division of Cardiology, University of Alabama in Birmingham, Birmingham, Alabama.

The mechanism of “ectopic atria1 tachycardia” (EAT) is generally thought to be automatic. We studied fourteen patients with sixteen episodes of ectopic atria1 tachy- cardia with rapid atria1 pacing. Eight patients demon- strated entrainment during rapid atria1 pacing. The average atria1 cycle length of these eight patients was 306 msec (range 260 msec to 400 msec) and all demonstrated the presence of AV block without interruption of the tachycardia sometime during their study. Rapid atria1 pacing was initiated at or slightly above the ectopic atria1 tachycardia atria1 rate and incrementally increased until interruption of the arrhythmia occurred. Transient entrainment was manifest as: (a) acceleration of the ec- topic atria1 tachycardia during rapid atria1 pacing to the pacing rate, (b) constant atria1 fusion during atria1 pacing, (c) return of the ectopic atria1 tachycardia to its original atria1 rate without interruption upon dis- continuation of the pacing, and (d) absence of overdrive suppression (i.e. the first return atria1 cycle after termination of pacing and subsequent atria1 cycle length not exceeding the original ectopic atria1 tachycardia atria1 cycle length). Thus, in this study group, many patients with ectopic atria1 tachycardia demonstrated transient entrainment, a finding which strongly suggests a re-entrant rather than an automatic mechanism.

ELECTROPHYSIOLOGY OF LONE ATRIAL FIBRILLATION Ross J. Simpson, Jr., ;l.O., James R. Foster, il.0.. Leonard S. Gettes, X.D., University of North Carolina, Chapel Hill. N.C.

Factors contributing to the initiation of atria1 fibrillation in patients with normal hearts are poorly uncierstood. To test the hypothesis that these patients have abnormalities of atria1 excitability and conduction we measured atria1 strength interval curves to study re- fractoriness, late diastolic threshold and conduction times of early and late premature beats in four patients with recurrent atria1 fibrillation (AF) in the absence of heart disease and six control (C) patients. All ten patients had normal left atria1 size by echocardiography and normal P wave duration on the electrocardiogram. Hone had cardiomegaly, failure, preexcitation or abnor- malities of sinus node function. Conduction times were measured from the high right atrium to the low septal right atrium (AHRA-AHIS) and to the coronary sinus (AHRA-ALA). ~_

There were no significant differences between AF and C patients in P wave duration, left atria1 size, the con- duction time of premature beats in late diastole or late diastolic threshold.

In AF patients the functional refractory period was shorter (270 + 35 vs 310 ? 25 ms, p < .05) and the amount of conduction slowing of early premature beats was greater (AHR -AHIS: 30 i 15 vs 10 * 5 ms. p < .Ol; AHRA-A A: 35 f eo vs 5 + 5 p < .Ol).

The factors responsibl: for these differences are not known. However, our results indicate that patients with lone atria1 fibrillation have abnormalities of atria1 refractoriness and conduction which may explain their propensity to atria1 fibrillation.

920 March 1982 The American Journal of CARDIOLOGY Volume 49