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Ann Thorac Surg 2000;70:1130-1133
© 2000 The Society of Thoracic Surgeons

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Supplement: cardiothoracic techniques & technologies

Symptomatic improvement after transmyocardial laser revascularization: how long does it last?

^a CardioThoracic Department, University of Pisa, Pisa, Italy

Address reprint requests to Dr Bortolotti, U.O. Cardiochirurgia, Ospedale Cisanello, Via Paradisa 2, 56124 Pisa, Italy
e-mail: u.bortolotti{at}cardchir.med.unipi.it

Presented at the Sixth Annual Cardiothoracic Techniques and Technologies Meeting 2000, Fort Lauderdale, FL, Jan 27–29, 2000

	Abstract

Top Abstract Introduction Material and methods Results Comment References

 
Background. The aim of this study was to determine whether short-term clinical improvement after isolated transmyocardial holmium laser revascularization (TMLR) in patients with coronary artery disease not amenable to traditional treatment is maintained through a longer follow-up.

Methods. Between November 1995 and June 1999 34 patients underwent TMLR (mean age, 67 ± 7 years); previous revascularization procedures had been performed in 76%. Preoperatively, mean angina class was 3.6 ± 0.5 in 12 patients with unstable angina; mean left ventricular ejection fraction was 47% ± 9%.

Results. There was 1 early death due to low cardiac output. Mean duration of TMLR and of the entire operation was 25 ± 12 minutes and 125 ± 43 minutes, respectively. There were no major postoperative complications; mean hospital stay was 8 ± 4 days. There were 8 late deaths caused by stroke (2 patients), cardiac failure (1 patient), and myocardial infarction (5 patients). Follow-up of current survivors ranges from 4 to 48 months (mean, 32 ± 12 months). At 1-year follow-up mean angina class was 1.8 ± 0.8; but at a later follow-up (mean, 35 ± 10 months) it significantly increased to 2.2 ± 0.7 (p = 0.005). Three-year actuarial survival was 76% ± 8% and freedom from cardiac events 44% ± 10%.

Conclusions. Our results show that after initial clinical improvement many patients experience return of angina or cardiac events; this questions the long-term symptomatic benefit of TMLR.

	Introduction

Top Abstract Introduction Material and methods Results Comment References

 
Transmyocardial laser revascularization (TMLR) has recently emerged as a valid alternative in patients with refractory angina and with coronary artery disease not suitable for coronary artery bypass grafting or percutaneous transluminal coronary angioplasty (PTCA). Preclinical and clinical studies using a high-power CO₂ laser have demonstrated that TMLR reduces angina and related hospitalizations and improves cardiac perfusion [1]. Furthermore, a prospective randomized trial in patients with refractory angina showed that TMLR, when compared with medical management, significantly improved event-free survival [2].

Recently a holmium-yttrium-aluminum garnet (YAG) laser has been introduced for TMLR [3]. A prospective clinical trial of TMLR using a holmium laser as sole therapy in patients with refractory angina was started in 1995 at our institution, with gratifying early results [4, 5]. We wanted to verify the stability and durability of the symptomatic improvement observed in our patients at a longer follow-up; the results are discussed in the present report.

	Material and methods

Top Abstract Introduction Material and methods Results Comment References

 
A clinical trial for TMLR as sole therapy for otherwise untreatable coronary artery disease was begun in November 1995. Our Ethical Committee had approved the study and informed consent was obtained from each patient. Inclusion criteria were presence of Canadian Cardiovascular Society (CCS) class III or IV angina, refractory to maximal medical treatment; evidence of coronary artery disease not suitable for PTCA or CABG; left ventricular ejection fraction 30% or greater; documentation of myocardial ischemia and viability by ²⁰¹Tl single-photon emission computed tomography (²⁰¹Tl-SPECT) during exercise or pharmacological stress. The presence of myocardial ischemia in those patients who could not undergo a stress test was documented by electrocardiographic changes during the episodes of angina and by reversible perfusion defects at basal ²⁰¹Tl-SPECT.

Surgical procedure
Details of the operation have been previously described [5]. Breifly, all patients underwent TMLR using a holmium-yttrium-aluminum garnet (holmium:YAG) laser (Eclipse Surgical Technologies, Inc, Sunnyvale, CA). The operation is performed on the patient’s beating heart through a limited left anterolateral thoracotomic incision on the bed of the fifth rib. The pericardium is opened anterior to the phrenic nerve and suspended. Major epicardial coronary vessels are identified, as well as previous venous or arterial grafts. Transmyocardial channels are created from the epicardium to the endocardium into the left ventricular cavity, in the areas showing reversible perfusion defects at ²⁰¹Tl-SPECT. Penetration of the laser probe into the left ventricular chamber is indicated by a change of the acoustic pattern of the system, rendering routine echocardiographic confirmation unnecessary. Bleeding resulting from the channel is easily controlled by digital compression.

Before beginning TMLR, lidocaine infusion is started to prevent ventricular arrhythmias. Volume losses are replaced with crystalloid solution, as the amount of bleeding is usually negligible. Antiarrhythmic treatment is continued throughout the first postoperative night, together with furosemide administration to avoid myocardial edema. The patient is extubated and discharged to the ward as soon as possible. Anticoagulants are usually not given but all patients receive antiplatelet drugs.

Study protocol
The study protocol included clinical assessment, exercise testing with cycle-ergometer, two-dimensional echocardiography, and ²⁰¹TI-SPECT myocardial scintigraphy. All examinations were performed preoperatively and at 3, 6, and 12 months after surgery and on a yearly basis thereafter.

Statistical analysis
Results are expressed as mean ± standard deviation. Preoperative data are reported on all patients, whereas comparison between preoperative and follow-up results are included only for those patients appropriate for a paired t test. Significance was set at p less than 0.05. The curves of overall survival and of freedom from cardiac events were drawn on an actuarial basis using the Kaplan-Meier method.

Patient population
From November 1995 to June 1999, 34 patients were treated by TMLR. There were 24 men and 8 women, with a mean age of 67 ± 7 years (range, 46 to 79 years). The main preoperative characteristics are summarized in Table 1. A total of 30 patients (88%) had sustained at least one myocardial infarction; in 8 patients (24%), two or more such episodes had occurred. A total of 27 patients (79%) had undergone at least one previous CABG and 13 (38%) had had one or more PTCA. Preoperatively 15 patients (44%) were in CCS class III and 19 (56%) in class IV (mean CCS class 3.6 ± 0.5); 14 patients (41%) required intravenous administration of heparin and nitrates. All patients received multiple oral medications consisting of various combinations of ß-blockers, calcium-channel blockers, and nitrates.

Preoperative transthoracic two-dimensional echocardiography was performed in all patients showing a mean left ventricular ejection fraction of 47% ± 9% (range, 30% to 60%).

	Results

Top Abstract Introduction Material and methods Results Comment References

 
Operative results
A total of 31 patients were operated through a limited left anterolateral thoracotomy, whereas in 3 patients a thoracoscopic approach was employed. The laser procedure lasted from 11 to 58 minutes (mean, 25 ± 12 minutes); mean duration of the entire procedure was 125 ± 42 minutes (range, 60 to 235 minutes). The mean duration of TMLR and operation in the 3 patients with thoracoscopic approach was 37 ± 15 minutes and 151 ± 31 minutes, respectively. The mean number of scintigraphic segments treated per patient was 6 ± 2 (range, 3 to 8 segments), and the mean number of transmyocardial channels performed per patient was 36 ± 9 (range, 13 to 46 channels). Mean postoperative ventilation time was 10 ± 7 hours (range, 1 to 24 hours), with a mean intensive care unit stay of 26 ± 21 hours (range, 9 to 126 hours). The 3 patients with thoracoscopic approach were extubated after 2, 4, and 3 hours, respectively, and all were discharged to the ward within 12 hours.

There was one operative death from myocardial infarction, but no other major postoperative complications were observed. Mean blood loss was 373 ± 212 mL and reoperation for bleeding was never required. Mild inotropic support (dobutamine 3 to 5 µg/kg/min) was necessary in 11 patients. In all, 4 patients experienced runs of ventricular tachycardia and 4 had transient ST-segment depression with negative T waves. Mean peak CK/MB was 46 ± 38 IU/L (range, 5 to 184 IU/L); enzyme elevation did not correlate with number of channels, electrocardiographic changes, or need for inotropic support. Patients were discharged 4 to 15 days after TMLR, with a mean hospital stay of 8 ± 4 days. The 3 patients undergoing a thoracoscopic approach were discharged after 4, 5, and 7 days, respectively.

Follow-up
In all, 8 patients died during follow-up: 5 because of myocardial infarction, at a mean of 22 months after TMLR (range 5 to 37 months); 2 because of stroke 40 days and 1 year, respectively, after TMLR; and 1 because of congestive heart failure after 3 months. Consent for autopsy was never obtained. Actuarial survival at 3-year follow-up was 76% ± 8% (Fig 1).

View larger version (12K): [in this window] [in a new window]   Fig 1. Actuarial survival at 3-year follow-up. Numbers along the time axis represent patients at risk.

Myocardial infarction occurred in 8 patients after TMLR and was fatal in 5. Freedom from myocardial infarction at 3-year follow-up was 73% ± 9%.

Considering only the 23 patients with a follow-up of more than 1 year, a slight but significant deterioration in their anginal status was evident compared with the 1-year follow-up, with the last follow-up obtained after a mean of 35 ± 10 months from TMLR. In fact, whereas at 1 year the mean CCS class of angina was 1.8 ± 1.8, at the last follow-up it was 2.2 ± 0.6 (p = 0.003), remaining, however, significantly better than the preoperative mean angina class (3.5 ± 0.5, p < 0.001) (Table 2, Fig. 2). At 1-year follow-up there were 9 patients (39%) in class I, 9 (39%) in class II, and 5 patients (22%) in class III; an improvement of three CCS classes was observed in 3 patients (13%), a two-class improvement in 10 (43.5%), and a one-class improvement in 10 (43.5%). On the other hand, at the last follow-up 2 patients (9%) were in CCS class I, 14 (61%) in class II, and 7 (30%) in class III; 7 patients (30%) maintained a two-CCS class improvement compared with their preoperative class, whereas the remaining 16 patients (70%) had only a one-class improvement.

View larger version (16K): [in this window] [in a new window]   Fig 2. Mean Canadian Cardiovascular Society class of angina before operation, at 1-year follow-up and at last follow-up (35 ± 10 months after operation) of the 23 current survivors followed for more than 1 year.

Among current survivors, 7 patients suffered return of severe angina (CCS class III to IV) after TMLR. Freedom from severe angina at 3-year follow-up was 61% ± 9%. Actuarial freedom from cardiac events (death from cardiac causes; myocardial infarction; or return of severe angina) at 3-year follow-up was 44% ± 10% (Fig 3).

View larger version (14K): [in this window] [in a new window]   Fig 3. Actuarial freedom from cardiac events (death from cardiac causes, myocardial infarction, or return of severe angina) at 3-year follow-up. Numbers along the time axis represent patients at risk.

	Comment

Top Abstract Introduction Material and methods Results Comment References

 
Transmyocardial revascularization is a technique that aims to create transmural channels from the endocardium into the left ventricular wall, thus allowing direct perfusion of ischemic myocardium with oxygenated ventricular blood. After extensive experimental work, clinical trials of TMR with a CO₂ laser in patients who were not candidates for other interventional therapies have shown encouraging early results with an improvement in anginal status, exercise tolerance, and event-free survival. Recently, holmium:YAG lasers have been employed clinically [6]. When compared with CO₂ laser, one great advantage of the holmium-YAG laser is represented by a pulsed energy delivery with a shorter tissue interaction time, thus determining a greater photoablative effect on tissues and less thermal effects. Furthermore, the laser beam is conducted through a flexible fiber that permits easy reach of almost any area of the myocardium and also allows the procedure to be safely performed through a thoracoscopic approach.

In November 1995 we started a clinical trial using a holmium laser as sole therapy for patients with untreatable angina. Our initial experience has shown that TMLR performed with a holmium laser is a safe and low-risk technique, with mortality and morbidity comparable to those previously reported with a CO₂ laser [7]. Our results are also consistent with the increase in exercise tolerance and the significant reduction in mean CCS angina class and number of hospitalizations reported by others for TMLR with both CO₂ and holmium lasers [6, 7].

In the present study we wanted to verify whether the clinical benefits of TMLR were maintained at a longer follow-up. We observed that the reduction in mean CCS angina at last follow-up is still obvious when compared to preoperative values. However, the clinical benefits of TMLR at the 3-year follow-up appeared to be significantly reduced with respect to the follow-up at 1 year. This might indicate that the early symptomatic improvement obtained by TMLR is of limited duration, as reported also by others [8].

Another interesting finding was that myocardial infarction was the cause of late death in 5 patients, 3 of whom were in angina class I at the time of event. This indicates that, after TMLR, patients still face the complications of myocardial ischemia, even if they are angina-free. In our opinion the reduction of angina, together with an improved exercise tolerance, may subject such patients to repeated asymptomatic episodes of myocardial ischemia, which could jeopardize their long-term survival. Therefore, reduction of medical treatment after successful TMLR should be cautiously evaluated on an individual basis.

In conclusion, TMLR with a holmium laser can be considered a low-risk procedure, yielding early clinical improvement in the majority of patients with severe angina unsuitable for conventional treatment. However, extendsion of follow-up up to 3 years after TMLR shows a trend to return of angina, indicating that the clinical benefits of the procedure are probably more limited than initially expected. Furthermore, the high incidence of cardiac events suggests that a closer surveillance of such patients is warranted as follow-up progresses.

	References

Top Abstract Introduction Material and methods Results Comment References

 

1. Frazier O.H., Cooley D.A., Kadipasaoglu K.A., et al. Myocardial revascularization with laser. Preliminary findings. Circulation 1995;92:II58-II65.
2. Allen K.B., Dowling R.D., Fudge T.L., et al. Comparison of transmyocardial revascularization with medical therapy in patients with refractory angina. N Engl J Med 1999;341:1029-1036.[Abstract/Free Full Text]
3. Yano O.J., Bielefeld M.R., Jeevanandam V., et al. Prevention of acute regional ischemia with endocardial laser channels. Ann Thorac Surg 1993;56:46-53.[Abstract]
4. Milano A., Pratali S., De Carlo M., Pietrabissa A., Bortolotti U. Transmyocardial holmium laser revascularization. Eur J Cardiothorac Surg 1998;14(Suppl 1):S105-S110.[Abstract/Free Full Text]
5. Milano A., Pratali S., Tartarini G., et al. Early results of transmyocardial revascularization with a holmium laser. Ann Thorac Surg 1998;65:700-704.[Abstract/Free Full Text]
6. Allen K.B., Dowling R.D., Heimansohn D.A., Reitsma E., Didelot L., Shaar C.J. Transmyocardial revascularization utilizing a holmium:YAG laser. Eur J Cardiothorac Surg 1998;14(Suppl 1):S100-S104.[Abstract/Free Full Text]
7. Frazier O.H., Kadipasaoglu K.A. Transmyocardial laser revascularization as a new therapeutic option for refractory coronary artery occlusive disease. Eur Heart J 1998;19:1420.
8. Landolfo C.K., Landolfo K.P., Hughes G.C., Coleman E.R., Coleman R.B., Lowe J.E. Intermediate-term clinical outcome following transmyocardial laser revascularization in patients with refractory angina pectoris. Circulation 1999;100:II128-II133.

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